Growing marijuana outdoors can be as simple as putting seeds or seedlings into the ground and only coming back for the harvest. Nevertheless, using autoflower outdoor nutrients can turn even an average producer into a xxl strain. We’ll show you what nutrients to feed your autoflower plants outdoors.
Often, it’s Best to Go Organic
We personally have achieved great results by simply growing autoflowers next to tomatoes and giving both the same treatment.
If the soil is rich enough for a regular vegetable garden, just amend it with some organic supplements, like wood ash, a few handfuls of compost from your compost pile, or some composted manure. Then, throughout the season, just add grass clippings or heaps of weeds. They will serve as both the mulch and the source of nutrients that will slowly seep into the ground.
You can further increase the availability of organic nutrients to your autoflower plants by inoculating the soil with beneficial microbes. There are lots of inoculants on the market today. These ones are most often used for cannabis:
Advanced NutrientsVoodoo Juice – 5 billion beneficial bacteria in every liter,
Advanced NutrientsTarantula – 10 million viable beneficial bacteria per gram,
Advanced NutrientsPiranha – a special combination of ecto and endo mycorrhizae,
Bush DoctorMicrobe Brew – concentrated fungi and bacteria + nutrients.
You Can Use Cheap Generic Nutes
Nothing is easier than going to the nearest gardening center and buying a bottle of nutrients that was designed for other crops, but can as well serve an autoflower grower.
As always, make sure that for the vegetative growth you use a fertilizer that contains more N (nitrogen) than P (phosphorus) and K (potassium). And when your cannabis starts to flower, switch to a fertilizer that shows more P and K in its N-P-K numbers. Read the instructions on the label carefully and try not to give your autoflowers more than ¼ to ½ of what’s recommended. Hungry weed is always healthier than overfed weed.
If there’s a choice between organic and synthetic nutrients, we suggest that you choose organic ones. This way it’s easier to avoid overfeeding and nutrient burn, and the smoke will be cleaner, healthier, and more flavorful.
Autoflower Outdoor Nutrients Specifically Designed for Cannabis
Today, there is a big, thriving, and rapidly growing industry that caters to weed growers. So there are many exciting and even miraculous products on the market. Let’s look at some of them.
Fox Farm Nutrients
FoxFarm produces a wide range of products for different crops. Some of them are quite effective as autoflower outdoor nutrients. It’s arguably more convenient to choose some of their dry fertilizers for an outdoor grow, including slow-release formulas. Another good option would be soluble products because they are cheaper than liquid ones.
Here are three examples:
Marine Cuisine (NPK – 10-7-7) is a slow-release organic nutrient; it’s a mix of sea plants that you’ll only have to apply once at the beginning of the season.
Open Sesame (NPK – 5-45-19) is a high-phosphorus fertilizer that will stimulate the formation of flowers at the start of the budding stage.
Beastie Bloomz (NPK – 0-50-30) contains high amounts of phosphorus and potassium which will boost the swelling of your buds.
Fox Farm’s Open Sesame & Beastie Bloomz: Both worked well. I misjudged how long my plant was gonna flower for so I didnt get to use these at the exact moments I had wanted to but everything turned out beautiful.
Earth Juice’s Bloom Original Formula & Catalyst: I added this at the end in hopes to increase potency or resin production but once again I misjudged my plants bloom cycle so it wasn’t as effective as it could have been
Green Buzz Liquids offer 100% organic fertilizers which are fine tuned to the needs of cannabis plants at the different stages of their development. You can purchase not only well-balanced formulas of macronutrients (NPK), but also a lot of amendments, boosters, and enhancers.
Organic Grow & Bloom (NPK – 4-2-6 and 2-3-4), for veg and flower phases, respectively,
Organic More PK (NPK – 4-6-10), to really boost the budding,
More Roots, to increase the root mass,
Humic Acid Plus, to stimulate nutrient uptake,
Fast Buds, for faster transition to flowering,
Big Fruits, for up to 25% bigger buds,
Living Organics, another great inoculant to make plant food more available and protect cannabis from environmental stress.
Green Buzz Liquids: they went along nice with this grow,mutated my buds into hard rock solid ones,as to expect from good nutes
CANNA make their products specifically for marijuana growers, that’s why any of them can be used as autoflower outdoor nutrients. Even those that are meant for a totally different medium and setup, like an indoor grow on coco coir.
CANNA is what the grower quoted below used (along with many Advanced Nutrients supplements). The fertilizer formula that he chose is CANNA Coco A+B. It consists of two bottles. You add both one after another and together they have the NPK of 5-4-3. Besides, they contain all necessary micronutrients.
Canna: Easy to use, does what it says on the bottle.
Advanced Nutrients: I have been impressed by the results I have seen with this brand. I may change my base nutrition to the connoisseur range on my next grows.
This company is very popular with cannabis growers and for a reason. BioBizz products are reliable and easy to use. The staple of their line are Bio-Grow (nutrients for veg), Bio-Bloom (nutrients for flower), and Top-Max (blooming stimulator). However, for their Outdoor Try-Pack BioBizz have chosen a different set:
Bio-Bloom, the perfect ratio of NPK + enzymes & amino acids,
Fish-Mix, fish emulsion + Dutch sugar beet extract to feed beneficial bacteria in the root zone,
Top-Max, a mix of of humic and fulvic acids.
In the grow cited below, the gardener used another two supplements:
Alg-A-Mic, seaweed extracts to prevent or overcome stress,
Acti-Vera, an aloe vera extract to make plants stronger and healthier.
BioBizz: Excellent product worth the extra money compared to Flora Series
When looking for autoflower outdoor nutrients, never ever forget about Advanced Nutrients. We have already mentioned their two inoculants—Tarantula and Piranha. But this company offers a very long list of exciting nutrients and supplements. Below are just a few of them:
Big Bud, a careful blend of P, K, and amino acids,
Bud Factor X, boosts the production of resin and terpenes like no other,
Bud Ignitor, for faster onset of flowering and more numerous bud sites,
Bud Candy, sugars, aminos, and vitamins for huge and sweet-tasting buds,
B-52, a source of vitamin B for stress & heat resistance and better nutrient uptake,
Flawless Finish, to flush your buds for cleaner and tastier smoke.
Advanced Nutrients: Maybe I used too much nutrients, next time I will try and find a balance… | Bud Ignitor: Incredible boosting Flawless Finish: From now on i will always use this Advanced Nutrients product. I’m in real love with this one
B.A.C.: I have nothing bad or good to say, just a good nutrient brand.
Atami: It’s a 10. Essential #1, this product has been, is and will be the best.
An outdoor cannabis grow shouldn’t be complicated or expensive. Odds are that any weedy patch will turn into a great garden and bring you enough bud to live through the winter. But if you decide to spend some money on nutrients, the result can be even better. And we have got you acquainted with a few reputable producers whose products won’t let you down.
And maybe you already have some outdoor growing experience—good or bad—with a specific line of nutrients. Please feel free to share it with your fellow-gardeners in the comments section.
Cannabis Seedling Problems: How to Resolve Any Issues
Newbie growers tend to run into cannabis seedling problems with their plants from day one. That’s why our diagnosis tool can come handy to you. Start by finding your cannabis seedling issues in the list below (we tried to group them for more convenient navigation), and then use page jumps (or scroll down) for possible causes and solutions.
Too often, when a weed seedling is sprouting from the medium, the cotyledons are still stuck in the shell and it won’t come off on its own.
This is day 1 for three OG Kush Auto seedlings. Only one of them has cast off its shell on its own.
Probably, most seedlings will find enough strength to eventually shed the shell, but meanwhile a lot of time will be lost and you’ll see a lot of stretching. So you have to remove the shell yourself as soon as possible. Moisture is the key here. If the seedling is still tiny and can be covered by moist medium, by all means do so. Probably it will be enough. If not, the shell will be wet enough in a couple of hours, so that you can easily remove it with your fingers.
If the seedling is already too tall to be covered with wet soil, spray it with water or put a droplet of water on the shell: this will make it wet and mushy after a while. Then remove the shell with your fingers.
We’re wetting the shells with a drop of water. It will be enough to easily remove them from cotyledons.
Sometimes the shell comes off, but a thin membrane covering the cotyledons remains. Usually, it’s the reason why weed seedling is not opening. The membrane is too dry and acts as a straightjacket. Make it wet and when it gets soft, pluck it with your fingers. It usually slips off quite easily.
We have removed shells from the seedlings on the right and in the center. The one in the center still retains the membrane.
Warning: Sometimes, the seedling hasn’t rooted too deeply and has still a very short tap root (like an inch or so). In this case, the procedure described above can result in your plucking the sprout out of the soil completely. So never apply excessive force. It’s better to make the shell wet again and wait a bit more. If you did pull the sprout out of the ground, you can still stick it back in (probably, it’s best to remove the shell first). Most seedlings can survive this without apparent shock or stress.
In your future grows, make sure that sprouts emerge from the medium already without a shell. Keep the surface of the medium moist at all times, and you probably should think about placing the seed a little deeper than you did before. In this case, the seedling will encounter more resistance on its way up and the shell will slide off.
Seedling Stretching: Reasons and Solutions
Most seedlings are tall and skinny and look vulnerable, and generally it’s not a problem. But sometimes the stem is growing too tall, weak and thin and can’t support the weight of cotyledons anymore. As a result, the long stem is not growing straight, but sideways or even upside down. The reason is simple: there’s not enough light. Either the source is too weak (e.g. you keep your seedlings on the window sill), or the light is placed too high above. In either case, seedlings stretch toward light uncontrollably and keep falling over.
We still recommend that you play it safe the first couple of days and keep the light at a distance. Let the seedling reach the height of 2-3 inches (5-7 cm) – it’s normal and healthy and much better than the other way around: when the sprout is stressed by too much light (and sometimes heat). Slowly correct the distance before you see the seeding bending, leaning or even falling over. In time, you’ll know the exact distance for your type of bulb.
But what to do if a seedling already bent and flopped over? You can always use a toothpick to prop a weed seedling not standing up. However, it is best to make the stem that is too long shorter. You can do this by adding more soil (or coco, or other medium) – then the part of the stem that you cover by the medium will grow more roots, and it’s great. Or, if the container isn’t tall enough for that, you can press the seedling to the soil horizontally (it’s easy when the stem is already bent or the seedling fell over) and cover it with a thin layer of soil. If there’s too much resistance, gently crush the stem with your finger tips, probably just above the surface – it won’t really hurt the seedling.
This seedling has clearly stretched too much and needs to be made shorter. Strart by crushing its stem with your fingers just above the surface of the soil and then do the same in several places above.Now that the stem is soft and pliable, lay it on the soil, probably in a half-ring shape.Now cover the bent stem with soil and don’t forget to water. Note that this procedure will slow down the growth a bit, compared to seedlings that you didn’t let stretch in the first place.
The Problem of Weed Seedling Damping Off and Other Root Problems
Stunted growth, or slow growth, is common among cannabis seedling problems. The reason can be anything: from wrong conditions to stress to shock, but here we’ll talk about problems in the root zone. Healthy root growth is the single most important factor for a plant’s well-being, and if you see that your marijuana seedling stopped growing or is growing very slow, or especially if cannabis seedlings keep dying on you time after time, the first thing to check are the roots and what’s going on with them. Are they affected by some type of fungus? Is there root rot?
Most of the time, these problems arise when the medium is constantly wet and cool at the same time. These are ideal conditions for mold and fungi, and can lead to the weed seedling damping off. Apart from the seedling not growing leaves or its slow growth in general, you will notice that the stem gets very thin just above the surface. Next thing it will flop over. And, of course, you may notice some whitish substance on the surface of the soil. When the soil feels damp and cold to the touch, it happens very often. And the problems are not just on the surface, but more importantly deep down, too.
Cannabis Seedling Problems Can be Caused by Bugs
Another reason why a seedling has sprouted but is not growing is that some kind of bug living in the soil has eaten the tap root. You wonder why the seedling won’t grow without realizing that there is in fact nothing at all below the surface, no roots to speak of. This sprout will die, and there’s nothing you can do about it. To prevent this from happening in the future, kill all the parasites in the soil with heat. Just make the soil wet and place it into the oven at around 200° F (90-100° C) for a half hour or so.
A Root-Bound Seedling is Hardly Ever a Problem
Some novice growers wonder if a cannabis seedling can become root bound. It’s the situation when there is too little room in the medium, so that the roots reach the sides of the container and start to grow along them, simply because they have nowhere else to go. It’s quite a common situation for mature plants growing (or shall we say ‘not growing’?) in too small pots, but seedlings generally haven’t enough time for their roots to use up all available space. So seedling becoming root bound is hardly ever an issue.
And, of course, if you feel that your marijuana seedling is growing slow or not growing fast enough for you or is very short, make sure that you don’t expect too much. Read about the healthy and normal seedling development here.
The Seedling Gets Too Much Light
Most marijuana growers would swear that the more light the better. However, the issue of too much light is the real thing, especially for weed seedling. We have been sent countless pictures of seedlings showing the signs of stress from too much light. To be frank, we sometimes (erroneously) diagnosed the issue as potassium (K) deficiency which is often manifested by the lower leaves turning yellow at the edges. However, if you see this symptom in sprouts, the first thing you should suspect is that you have a source of light that is too intense or too close.
You may ask why then this symptom (yellow spots along the edges) appears not on the topmost leaves, but on the lower ones? Well, it’s because the lower leaves have had more exposure to the stressful levels of light (simply because they are older and have been around longer). Leaves yellowing due to too much light are very rare if you use CFL or T5 lights, but with HID (high intensity discharge) bulbs, like HPS or MH, or with the LED technology, these problems are very common.
Too Much Light and Heat Stress Often Go Hand in Hand
If you see seedling leaves turning white, sometimes to the point of complete bleaching, it also can be caused by too much light, but also made worse by heat stress (see below) and maybe calcium deficiency (these two often come hand in hand). Remember that for plants grown in coco calcium deficiency is especially common.
Another sign that your light is simply too much for this stage is that the seedling stays very short. It not only has no reason and motivation to stretch toward the bulb, but the dense flux of photons is constantly pounding on it, causing it to keep close to the ground.
If you see any of these signs, simply raise the lights, or use weaker ones.
This seedling was exposed to the harsh light of a LED bulb for too long. That’s why its cotyledons and the first pair of true leaves look yellow, dry, and brittle.
Another severe case of too much light. Again the culprit is a LED bulb that was kept too close to the seedling.
These two plants stand next to each other under two CFLs each. There’s clearly something wrong with their lower leaves. Our guess is they have received too much light. See how compact and dense they are.
Cannabis Seedling Problems with Nutrients
When you see a yellow leaf on your seedling, it’s not necessarily the symptom of too much light (as described above). It can also be a nutrient deficiency. It is seldom the case in soil, because soil mixes come preloaded with fertilizers, organic or synthetic, and it’s enough for the first two weeks or so. But if you use some sterile medium like coco or rockwool, it’s your job to provide your seedlings with plant food. Unfortunately, it’s more than easy to make mistakes here.
This seedling looks yellow and sickly. Most probably, it suffers from many deficiencies, including N deficiency. Note that the medium here is coco. In soil, you can give your seedlings only plain water and still see no deficiencies whatsoever.
Read carefully the instructions for your nutrients formula and follow them, not forgetting to adjust the dosage for various stages. Look at the color of your seedling: its leaves should have a healthy and vibrant green color. If leaves are light green or yellowish or you see yellow cotyledons, it could be nitrogen (N) deficiency. Although sometimes, if you overwater your young plants for days and weeks, they can show the same symptom (but there will also be others, more specific; see below).
If the seedling is dark green, it looks more like N toxicity (too much nitrogen). In severe cases, seedling leaves will also be curling down.
If you see such deep, dark green color of the leaves, probably you’re feeding your plant too much nitrogen (N).
This is how nitrogen toxicity can look in a mature plant. Also check if it’s not a wind burn (if there isn’t a fan too close to the plant).
We already mentioned seedling bleaching and white spots while discussing the problem of excessive light, and mentioned that it could be caused or made worse by calcium deficiency, most common in coco.
And surely there is this widespread symptom of leaf tips turning brown which is a sign of nutrient burn. It simply means that the dosage of fertilizers that you give your plants when watering (or that is present in the soil mix) is way too high, and you should lower it when you see your seedling burn like this.
Discoloration Isn’t Always a Sign of Trouble
When you suspect that the color of your seedling is not quite normal, maybe you’re wrong. Of course, yellow hues should always raise a flag. The exception is when you look at a plant the first thing in the morning and see yellow in the middle of uppermost young leaves or yellow veins. It could simply mean that this is the new tissue that has grown in the dark and simply hasn’t had a chance yet to be filled with green chlorophyll. Expose it to light, and it’ll become green in no time.
Stem color can vary from plant to plant. It can be white, red, purple, and sometimes even brown. If there are no other worrying signs, it’s probably natural and caused by the specific genetics. Purple stem, veins, or whole leaves can also be due to colder night temperatures (in genetically predisposed strains). So when your seedling is turning purple, see if it doesn’t get too cold at night.
Heat Stress is Common Among Cannabis Seedling Problems
If your weed seedling experiences heat stress, it affects the shape of leaves in a very specific way. You may see the leaves pointing up.
Back in the day, we used to keep CFL bulbs too close to the seedling, and, instead of shying away from it, the seedling seemed to try and hug the bulb with its upper leaves. Other growers see it differently: to them it seems as if the seedling were praying. Still others name it ‘cupping’.
The underlying cause is the same though: not able to move away from the light, the seedling tries to position its leaves in such a way that the light falls on them only obliquely. This helps them absorb less heat energy. If you continue to expose your plants to heat (be it hot air, or the energy from the light), you’ll see a more sinister symptom: leaf edges curling up. The heat often aggravates calcium deficiency and vice versa.
To combat this problem, always try to maintain the correct temperature range in your grow room and make sure the light isn’t close enough to burn. The ‘backhand test’ can help you with that. Place your hand palm down under the light at the level of plant tops and hold it there for some time. If you feel the light ‘bite’ or there’s any discomfort, it’s best to raise the light.
If leaves on your cannabis plant (at any stage) curl up like this at the edges, it means they are overheated by light or hot air.
This young plant kept under a CFL has grown so fast overnight that it actually touched the bulb. Hence the burned leaves on top.
Water Stress (Overwatering / Underwatering)
Newbies overwater marijuana all the time. Luckily, the plants have a way of showing their caregivers that they overdo the watering. The first sign of overwatering is clawing of the leaves, of their curling down. When you touch the leaves on an overwatered plant, you’ll feel that they are quite rigid. Conversely, if the leaves are pointing down, but feel limp and lifeless, the seedling is probably underwatered.
Leaves on this seedling are shriveling up and curling down. The plant has clearly been overwatered. At the same time, it shows signs of heat stress.
Leaves can even change color because of water stress. If you keep them overwatered for long periods, they’ll begin to yellow and eventually die off. The bottom line is: when you see marijuana seedlings shriveling up, correct your watering schedule.
This chronically overwatered cannabis seedling has leaves that look yellowish and lifeless along the edges, almost as if they were touched by frost.
Sometimes, weed seedlings have wavy leaves. We don’t know the exact reason why it happens, but have this theory that the issue is due to irregular watering. No one has yet disproved this theory, and we continue observations. In any case, it’s not a grave symptom. Seedlings with wavy leaves may not look fit for a beauty contest, but are otherwise healthy and vigorous.
All of these seedlings have wavy leaves: a not uncommon symptom. Probably, at some earlier point, the grower has overwatered these plants.
Wind Burn
Another reason weed leaves can become deformed is when there is strong wind blowing on them all the time. For instance, you may have placed a fan close to a seedling, and it’s blowing straight at it and not above it. After a while, it may cause wind burn. Leaves that are stressed this way are pointing down and forming ‘claws’ similar to overwatering. But in this case, they also curl at the edges in the shape of tubes. Often, they also have dark green color, like they do when there is too much nitrogen in their feed.
Weed Seedling Mutations
Deformed, twisted, shriveled leaves – these symptoms can appear in marijuana seedlings for no reason and should be considered mutations. These plants are never the best specimens in terms of growing, but, if you bring them to harvest, the smoke may surprise you. It’s up to you to choose what to do with mutants. Seeds don’t come cheap, and you may decide to grow every one of them. That said, breeders always discard seedlings with leaves twisting, as well as with other mutations. There is one interesting mutation though that we personally wouldn’t mind to keep and propagate: weed seedlings with 3 leaves. Usually, leaves grow in pairs, opposite each other on the stem. But here you have three leaves growing from every node. Delightful!
Twisted leaves point to some kind of mutation. You can still succesfully bring this plant all the way to harvest, but it’s not the genetics that you’d want to keep.
A rare and cool-looking mutation: a cannabis plant with 3 leaves.
Physical Damage: When a Seedling Can and Cannot be Saved?
A special case of seedling problems is when a grower damages it by mishandling. A seedling can be knocked over and uprooted. If you don’t disturb the root system too much, the more vigorous sprouts can survive the repotting without even slowing down their growth.
Root damage is a bigger issue. It often happens during transplant when a piece of soil falls off, tearing off a part of the root ball in the process. You just put the rest back in soil, and hope for the best. When the root broke, it’s a significant stress for a seedling, so try to make its life for the next couple of days less stressful. You can do this by creating milder conditions, like light and temperature, and, of course, refrain from any major changes (repotting, switching to 12/12, or moving outdoors) until the damaged seedling resumes its growth.
And what if the stem broke? Partially broken stem can heal, no doubt about it. Just make a splint and put a bandage where the seedling snapped, and the tissue will not only heal, but even be stronger. Even if you break the stem clean off, it arguably can be made whole again in this way.
What you can’t do is make any use of a seedling that only consists of the roots and the stem, but no growing point, in other words no leaves, as when something has eaten them. The thing is that cannabis doesn’t grow from roots. There are simply no growing points there, so you can’t salvage such seedlings.
Say Goodbye to Cannabis Seedling Problems!
Most cannabis seedling problems can be resolved, and quite easily, too. Just don’t freeze with panic and use common sense. After all, there’s nothing magical about cannabis. It’s just a plant, and one that is quite hard to kill. And if you fail to save a particular seedling, learn not to repeat the same mistake next time.
Cannabis Seedling Care: Tips and Optimal Conditions
If you want great results come harvest time, start to build your success early — with the proper cannabis seedling care. This includes creating ideal conditions for your seeds when they still germinate and following our tips for the best practices during the seedling stage. It will save you time growing your sprouts and ensure that they move to the next stage (the vegetative one) full of vigour and in the best possible shape.
Medical marijuana is mostly grown indoors. And even if you keep your adult plants outside, you’d want to start them inside. The reason is that the seedling stage is the most delicate and vulnerable in the cannabis plant’s life. So most of what follows deals with indoor growing: a grow tent, a growbox, a special marijuana seedling starter kit, or even a window sill. And if you are willing to risk starting your sprouts outdoors, scroll to the bottom part of this article.
Also, some of you have probably never grown pot before. So you have no idea how a healthy young plant looks like, how fast it grows, and what are the stages of its development. We suggest that you read our article on weed seedling anatomy and growth progress (where you can also look at pictures). And if you suspect that you have run into some problems with your sprouts, read our guide to diagnosing and resolving cannabis seedling issues.
Cannabis seedling care is a very easy thing. Young plants don’t require much light, water and nutrients, and there’s very little that you can do in the way of plant care. Instead, focus on creating the best possible conditions and then simply sit on your hands.
Marijuana Seedling Temp and Humidity
Temperature and humidity are of utmost importance. Moisture is what sets off marijuana germination, and the correct/ideal temperature range allows sprouts to grow vigorously from day 1. For marijuana in general, 70-90° F (20-30° C) temps during the day (when lights are on) is acceptable. But it’s better to aim at 73-82° F (23-28° C). Seedlings prefer the upper part of this range. Let’s say 80-82° F (26-28° C). The night temps should be about 5° lower.
Temperature (day)
80-82° F
26-28° C
Temperature (night)
5° lower than day temperature
Relative Humidity
60-70%
The correct humidity range for cannabis is the same as is recommended for human dwellings: 40-60%. It’s very convenient for those who grow at home. Seedlings prefer a bit more humid conditions than vegging or flowering plants. So aim at 60 to 70 percent, and you’ll be alright. If the air in your grow room is drier than recommended, you can use a humidity dome to cover your sprouts. Better still, buy a starter kit for seedlings which comes not only with a dome, but also with a heat mat. This allows for easier temperature control as well.
Weed plants need light throughout their life cycle, but during the seedling stage not really so much. And if you wonder how much light is ideal, we recommend to err on the side of caution.
It’s hardly the best option to keep your cannabis seedlings under HPS grow lights. Use weaker lights, instead, like CFLs, T5s, or LED lights. This will not only allow you to save on electricity, but spare your sprouts from shock. And if you insist on using HPS or other high intensity discharge (HID) lamps, raise them high, probably as high as your grow room allows.
Still, under light of this type, seedlings can show signs of stress, slow down their growth, and demonstrate various worrying symptoms. In this case, though it may seem counterintuitive to you, you’ll see better results if you temporarily keep your weed in the window — until it’s mature enough to handle strong light.
Some growers do it even before their sprouts emerge from the medium. Others wait first for the germination to complete. So, when the seeds break the surface, put them under light. Before that, it’s completely optional.
Distance from Light
If you follow our recommendations and use weaker types of light, like CFL, there’s a question of CFL light distance. The optimal light height is at least 4 inches (10 cm) for the first couple of days, even for such weak bulbs as 20W or so. Let the seedlings stretch toward light instead of being pounded by it. If you see that your seedling stays short and its leaves won’t grow or worse—turn yellow and dry—the light is too close.
The same goes for young plants that grow under T5 or under LED lights — keep a comfortable distance. Nobody likes stretchy plants and especially stretchy seedlings, but 2-3 inches (5-7 cm) in the first few days is healthy and desirable. Unless the stem bends over, it’s okay. So start far away and move the light closer, if your plants start to stretch too much. If you use LED and can measure PPFD, start with a conservative level of 200, although you can get away with 300-400, too.
Is Ventilation Important for Cannabis Seedling Care?
Very small plants obviously need very small amounts of light and water for photosynthesis, and, correspondingly, very little CO2. And one of the main reasons to use ventilation in your grow room is to provide plants with the fresh supply of CO2. The bottom line is you don’t really need any extractor fan for seedlings. But the other reason to use ventilation is to control temperature. If you need fans for that, by all means use them.
There is another type of fan that growers use in their grow tents — the one that blows air in the vicinity of plants and helps to mix air inside the grow space, to prevent mold issues, and to cause the plants to sway a little and thus make stems and branches stronger. You can use a fan on seedlings for this purpose, but be sure that it doesn’t blow directly on them. Otherwise, you might experience the cannabis seedling wind burn.
Marijuana Seedling Light Schedule
Even novice growers understand that cannabis needs light to transform its energy into plant matter. And the more light hours a seedling gets, the more energy it has a chance to absorb. So the question is: do marijuana seedlings need 24 hours of light?
They can certainly take it, no problem, but they hardly really need so many light hours. Many experienced growers argue that nighttime is important for plants because it gives them some rest which protects them from overstress. Besides, there is this theory that the root system grows more actively during dark and cool hours, so think about it when you decide not to turn off lights in the evening, or decide to give your plants a good watering before the lights-off. Either action won’t do your plants any good (probably).
So we suggest that you experiment with more conservative light schedules: 18/6 or 20/4. However, in our personal experience, the 24 hour light schedule works fine, too. Just don’t forget to change it to 18 hours of day and 6 hours of night when the seedling turns into a young plant, i.e. it enters the vegetative stage and starts to grow very rapidly.
Weed Seedlings Can be Grown in Various Mediums
The choice of the medium really depends on where you plan to keep your plants after the seedling stage is over and you are ready to transplant. It’s very convenient to put sprouts into rockwool for a DWC grow. When you grow in coco, it’s best to start in coco.
If your grow medium of choice is potting soil, use small pots or party cups filled with soil. As far as pot size is concerned, 8-10 fl oz (250-500 ml) containers should be enough for the first 2 weeks. Alternatively. you can grow seedlings in jiffy pellets or jiffy cups. Some growers look down upon them, but they are definitely convenient when you need to transplant without stress. Especially if you start your seedlings indoors but plan to move them outside.
Marijuana Seedling Transfer
You should never forget that repotting marijuana seedling is a risky and potentially stressful procedure that can slow down or even stop growth, and this is especially dangerous for autoflowers. If you don’t want to see your cannabis seedling drooping or wilting after transplant, you should do it as quickly as possible and give the root zone the least disturbance.
Don’t Fuss Too Much over Cannabis Seedling Care!
There’s only so much that you can do when your medical marijuana is still small. Apart from watering and maybe occasional feeding, sprouts hardly need any love and care. So let’s look at what you actually can do.
Watering (Obligatory, Duh)
This is the single most important thing of cannabis seedling care.
How much water do your seedlings need and when is best to give it to them? Well, if you keep your young plants in party cups or very small containers, it’s pretty straightforward: when the surface of the soil is dry and the cup or container feels light, it’s time to water. For a 8 fl oz cup (250 ml), 2 fl oz (50 ml) of water should be enough. For bigger pots, adjust the water amount accordingly.
It’s not recommended to put your seeds or sprouts into final size containers (where the plants will spend all their life, till harvest). This makes it very difficult to come up with the right watering schedule and calculate the ideal amount of water.
Watering Autoflower Seedlings
Autoflowers don’t like being transplanted, and it’s best to grow autos in the same container from seed to harvest. So, if you put your seedling in a big pot, you’ll probably need to water the whole container lightly once and then pour only very small amounts and only near the seedling, gradually widening this area and increasing the water amount. It’s difficult for a newbie and is best reserved for growers with some experience.
The Best Time of Day for Watering
Always try to water your plants in the morning, that is at the very start of the period when water is needed the most: for photosynthesis and perspiration. During the night, photosynthesis is nonexistent, and perspiration slows down. Besides, roots which supposedly grow most actively during the dark hours don’t need water for this, and an excess will suffocate them.
Feeding (Optional in Many Cases)
Grow your weed seedlings in soil and you’ll probably never need to feed them until they enter the vegging stage sometime after two weeks. It’s because a soil mix that you can buy in a store is pre-loaded with plant food. You can still try and boost the growth by giving your seedlings a very light dose of nutrients. Start with about a quarter of what a fertilizer manufacturer recommends. And even in this case, make your first feeding when the plant is at least 2 weeks old (1 week for risk takers and rule breakers).
Of course, in hydro or coco, there are no nutrients in the medium whatsoever. So, you’ll have to add some to your solution from the very beginning. We recommend 100 PPM for a start, with up to 400 PPM as you progress. It’s better to underfeed and increase the dosage as needed than overfeed and flush. Cannabis seedling and flushing are two things that don’t go well together
Marijuana seedlings need the same pH level as mature plants. pH is a constant throughout the plant’s life cycle. It’s 6.0-6.5 in soil and 5.5-6.0 in hydroponics.
Growing a Marijuana Seedling Outdoors
Believe it or not, cannabis does grow outdoors in the wild, but you’ve probably paid a pretty penny for seeds and aren’t eager to expose your precious seedlings to elements too early. We can only commend you for that. It’s best to start inside and put marijuana seedlings outside when they’re healthy, robust, and growing rapidly, and not younger than two weeks from sprout. At this stage, they can take pretty much any weather and not only survive, but continue to get bigger and stronger. If they are just a couple of days old, a heavy rain, let alone hail, can kill them.
However, we admit that some growers simply can’t start their seedlings inside. So when is it more or less safe to start your outdoor grow? Look at the weather forecast and choose a period when there can be no early morning frosts anymore, and the outside temperature during the day is at least 60° F (15° C). Mind you that at this temperature your seedlings will be in the survival mode. Look above for the correct and ideal temperature range.
As for sunlight—which can also be deadly for very young plants—you can provide some shade for them in the afternoon to protect them from full sun. The same principle applies when you start indoors and want to make your young plants get accustomed to the sun. We used to believe that marijuana seedlings shouldn’t be in direct sunlight for a whole day, but some experiments have shown that in spring this rule can be ignored. In summer, it’s best to expose your seedlings to direct sunlight only for a couple of hours in the morning and the evening when the air is cool enough, but never around noon.
Cannabis Seedling Care: Take Things Easy!
First-time growers tend to get nervous at the slightest sign of trouble, real or imaginary, especially during the germination and the seedling stage. But there’s no need to panic. Keep it simple, and you and your plant will be just fine!
