The Seedling Stage: Selection to Transplant and Care

There are seven stages in the cannabis growth cycle, and the second stop along the way to harvest is one of the most exciting phases: the seedling stage. 

Following the germination stage and preceding the vegetative stage, the seedling phase is a 2-3-week process that launches your plants’ initial growth. It’s imperative to treat your cannabis seedlings right, and this can be something of an enigma for novice growers. 

However, as long as you’ve set yourself up in a spacious environment, opted for the best genetics for your situation, and done your homework, your cannabis plants will thrive as little weed seedlings well on their way to sprouting those initial telltale leaves. 

Autoflower vs feminized vs regular cannabis seeds

Marijuana seedlings are born from successfully germinated seeds, and those will fall into one of three categories: autoflower seeds, feminized seeds, or regular seeds. Each seed type should be treated differently and will reap varying results, so it’s important to pick the right one for your growing situation.

Autoflower seeds are designed to bloom – surprise, surprise – automatically. The plants they produce flower on their own, and tend to grow faster and require much less maintenance from growers.

In general, autoflower plants are easy to cultivate, small-medium in size, and will enter the flowering stage within 2-4 weeks from the initial plant. The overall seed-to-harvest cycle will run about 10-16 weeks depending on the strain, but your yield will be on the lower side. 

On the other hand, feminized seeds are specifically bred to produce female photoperiod plants: a.k.a., the cream of the cannabis retail crop. Opting for feminized seeds results in an easy-moderate cultivation effort, and will produce medium-tall plants.

These cannabis plants require a 12:12 ratio of light:dark, and will go from seed to harvest in anywhere between 12-24 weeks (producing a medium-sized yield). 

These types of seeds are ideal for growers with a specific male-female ratio in mind, but if you’re interested in a more even balance between seed sexes, this route might put you out of whack.

Regular seeds are entirely natural, chemical-free, and are able to produce either male or female marijuana plants. The cultivation process will be a little more involved and advanced, but if you’re a grower who prefers to keep things as natural as possible, regular seeds will likely be your go-to. 

When deciding what kind of seeds you want to germinate in that damp paper towel, think about the type of cultivation process you want to endure and how many healthy plants you want to produce. These factors will help you determine which seeds make the most sense for you. 

Collect the right materials for your seeds

The seedling stage is also a time to plan ahead, ensuring your young plants have the best chance at growing the sets of leaves that indicate it’s time to enter the next stage.

You can do so by gathering the right materials to help set yourself up for success: like plant containers, optimal temperature and humidity levels, and a growing medium that pairs well with your environment.

You’ll want to keep drainage and aeration in mind: while your plants will be hungry and thirsty for water and nutrients, you don’t want to overwater or overfeed – especially at this stage. In fact, you should opt for a growing medium that has enough nutrients to sustain those seedlings until they move into vegetation. 

In regards to seedling containers, go for a good size for your plants to absorb water while not holding in any excess water. Your containers should also have holes in the bottom for drainage, and some sort of covering to maintain high humidity levels. 

Keep in mind that autoflower seeds are often better off being germinated in their final containers from the get-go, as damage that might occur to your root systems when you transplant can be tricky to recover from. 

Other things to think about include: pH level (this should sit at around 6.0-7.0), good lighting (18 daily hours of grow lights for indoor plants and six hours of direct sunlight for outdoor plants), and climate (seedlings can struggle in cooler locations, so be wary of the time of year you’re planting in). 

Germination techniques

If you’re opting for autoflower or feminized seeds, an RQS starter kit is a simple and streamlined way to initially germinate. But for regular seed growers, the tried-and-true paper towel method is a widespread classic. 

With this popular approach, all you’ll need is your seeds and a damp (not wet) kitchen towel. Simply place the towel on a flat surface, spread your seeds about two inches apart, and place another damp kitchen towel on top. When the root tips have grown about two millimeters long, it’s time to plant. 

Another simple but effective germination method involves a glass of water. Just place your seeds in one (in a dark area at about 68-77 degrees Fahrenheit) and wait for the root tips to hit that two-millimeter mark. Tada. 

When to transplant marijuana seedlings

As we mentioned earlier, autoflower seedlings don’t do well with transplantation, so if you’ve gone this route, you won’t have to worry about this step. However, feminized and regular seedlings are usually ready to go after about 10 days in this stage (but this can vary depending on environment and strain type). 

Other than these general tips, there is no one-size-fits-all approach when it comes to transplanting seedlings. Instead, you’ll have to pay close attention to your plants and know what to keep an eye on.

A popular best practice is to move your seedlings when the leaves fully cover their container’s circumference. Once that’s happened, check on the roots and see if they come out easily. If so, you’re ready to make the move.

Watering your cannabis seedlings

If you’ve been growing weed for a while, you probably know that plants grow best when they’re watered on a regular, balanced basis. Similarly to transplantation, there’s no universal law for watering seedlings, but if you know what to look for (and avoid), you’ve got nothing to worry about.

Generally, you want to ensure that your plants are never over- or under-watered. You can accomplish this by keeping a close eye on temperature and humidity levels, drainage and aeration, and light sources. 

Nutrient considerations

Seedlings are particularly susceptible to nutrient burn (damage caused by over-fertilization), and less is typically more for seedlings when it comes to feeding. 

Most successful growers don’t feed their plants at all during this stage, but if you must do so, make sure to opt for a diluted nutrient mix that’s high in nitrogen.

Pest Prevention

Cannabis seedlings are extra vulnerable to pests and disease, so it’s important to keep a careful eye on this risk. 

Neem oil is a popular product that growers turn to: a natural pest-fighter that is effective against aphids, thrips, spider mites, white flies, and mealybugs – all of which tend to gravitate towards cannabis. 

Your plants are also pretty good at telling you what’s wrong with them, which means there are quite a few signs to keep in mind if you fear your plants might have gotten infected (like limp, discolored, drooping, or curling leaves). 

Seed stretching

Cannabis seedlings are known for stretching – a natural impulse that allows them to move closer to their light source. But this can result in long, flimsy stalks, and may damage your yield in the long-run.

If you’re an indoor grower, a good way to avoid this is to grow with blue spectrum CFLs (positioned about five centimeters from the tops of your plants). You should also avoid keeping seedlings in the dark for 24 hours post-germination, because the lack of light may spark that unwanted seed stretching.