The right time to transplant your seedlings is just before they outgrow their current container. With cubes, you can see roots poking out telling you it’s time to pot up. When you start with a cup or small pot, you are relying on above-ground cues. Typically, when the set or sets of true leaves of the seedling have spread out to cover the circumference of the container, it’s time. Also, vertical growth will be an obvious indicator.
Rootbound plants will take time to recover and may be permanently stunted. In general, it takes 7–10 days for a seedling to take root and outgrow small starter pots of 1l or less. Either cut a hole to size in a bigger block, or burrow a hole into the medium with your fingers and insert for a snug fit. First, don’t fill your large container all the way to the top. If you pack the pot all the way to the top, water will mostly run off and not reach the roots. Next, make an impression in your large container with another small pot, or the one with the plant in it if you don’t have any others. Make this impression in the medium after you have watered it.
It’s best to wait until the medium in the small pot is dry before going for a transplant. Wet soil can fall apart in chunks as you fumble with the sopping mud. Now, turn the dry plant upside down, and firmly pat the bottom. Grasp the plant stem from the base and ease the compacted medium out of the container in one piece. Finally, gently slide the plant, roots first, into the large container. Replace the lost topsoil or coco with a handful or two over the top and add a little more water. If your final container size is up to 11l, you have the option to sow seeds directly. This is only a viable option when growing from seed. Clones will not take root in such a large container. Initially, seedlings in large pots will grow more slowly than those in smaller containers. After a few weeks of vegetative growth, the difference is negligible. If you don’t transplant, then you eliminate the risk of transplant shock. But you also limit the potential of your cannabis plants. That being said, a first and final transplant is sometimes the best option for autoflowering strains with a short life cycle. Unless smaller plants are advantageous due to limited grow space, bigger is always better. Transplanting is not something beginner growers should avoid. If you ever want to grow marijuana monsters, you need to master transplanting seedlings. Knowing how and when to transplant your cannabis babies can literally tip the scales in your direction when harvest time comes around. Learn everything you need to know about why, when, and how to transplant your cannabis. Healthy roots mean strong plants and fat, resin-jewelled buds on your cannabis. Whether you’ve decided to grow in a SOG, a ScrOG, or are keeping things super-simple, no matter what, you should transplant your cannabis into larger pots at least twice. There are, of course, some exceptions to this rule—which we will clear up later down the line—but first, let’s pose an all-important question. Unlike with hydroponics, growing in a solid medium like soil or coco makes transplanting into bigger pots necessary as your plants grow. As the roots expand into the substrate and seek out nutrients, their network will grow to encompass as much space as possible. When the roots have completely filled out the volume of the pot, running circles around the inside perimeter of the container, growers refer to these plants as “root bound”. Vegetative growth will slow down, ultimately limiting the potential of your yields as well.
By transplanting to bigger pots early on, we can prevent this from happening. Transplanting ensures the roots always have space to grow freely and vigorously. Contrary to what we said in the beginning of this article, you don’t technically need to transplant; but you should—especially if you want to max out yield. Plants grow faster in smaller pots but are more susceptible to overwatering and overfeeding. When you start in small seedling pots or solo cups, the risk of fungus and other growing problems is largely mitigated, but new problems arise once your soon-to-be vegetative plants want to establish a strong root system.
A good way to go about transplanting is to keep your babies in seedling containers until they’ve each developed at least three nodes. At this point, you can transplant your specimens into larger pots until they double in size.