How to Transplant Seedlings Without Spoiling Them
Most seeds are started in seed trays or seed blocks , but at some point these seedlings will outgrow their cage or block and will need more soil to grow their roots. In some cases, the weather evens out and you can transplant seedlings from the tray directly into the garden bed. But in most cases, your seedlings will need more time inside and protected before the weather gets warm enough, meaning you’ll need to remove the seedlings from the tray and give them a larger container where they can cool down and grow a little more before heading into the ground. This process is called “potting” and although the process itself is simple, there is actually a lot that can go wrong at this stage of the growing process. Here’s how to give your seedlings the best chance of survival.
How to Know When It’s Time to Raise Your Pot
When you buy plants from a nursery, their price depends on the size of the pot you buy them in—for example, a quart-size pot or a gallon-size pot. But if you pay attention, you’ll notice that the size of a plant in a 4-inch pot is often not much different from the size of a plant in a gallon pot. This is because the plant has been potted, a process that continually happens to plants as they grow. One easy sign that it’s time to repot is when roots are growing out of the holes in the seed tray. In seed trays, plants can easily become root bound (there isn’t enough room for the roots to grow, so they start growing in circles, tangling in on themselves), so it’s important to repot before this happens – if you wait too long, it can slow down the plants’ growth, which is the opposite of what you want.
You may also be repotting too early, before the seedling is strong enough to survive transplant shock. When vegetable and flower seeds grow, they form one or two leaves very early on – these are called “cotyledons” and are part of the seed itself. Later, the seedling will grow a second set, called “true leaves” because these are the first leaves that function as leaves. The cotyledons provide photosynthesis, and the true leaves serve as complete food for the plant. These sets of leaves look very different, and once you learn about the cotyledons, it will be easier to recognize them in your seedlings. You can’t repot until the true leaves appear and grow, and I would wait even later.
In addition to paying attention to the roots, I look at the seedlings themselves above the soil. When each seedling doesn’t have enough room to stretch, the plants are touching each other, or the seedling looks too tall for the cell or block, that’s my sign that the pot needs to be lifted.
Choose suitable soil for planting
When you grow seedlings, you use a seedling mix – it’s very low in nutrients and quite healthy, and it’s all designed to help the seeds grow. Now that your seeds are seedlings, they need nutrition and will therefore need a different potting mix. When replanting, use potting soil that will contain nutrients such as compost as well as moisture retention ingredients such as vermiculite.
How to choose the right pot
In most cases, you are going from a seed cell or block that is 0.75 to 2 inches in size, so a 4-inch pot is usually adequate. You will notice this in your nursery too. In some cases, tomatoes are replanted in quart containers, and you may end up needing this, but this is unlikely.
A good way to save money is to save those 3.5- or 4-inch pots from previous visits to the nursery or ask for them from any online gardening group. Some nurseries may have old ones that they will also give away. Keep in mind that they are intended for one-time use and therefore, with a good cleaning with hot water, will often break or become deformed. For a more durable option, you can purchase a set of reusable molded plastic pots , which is what I use. They stand up to cleaning and sterilization year after year, so you’ll rarely have to replace them, and they’re even dishwasher safe in cold or warm water.
However, for many gardeners, April is the time when they start making newspaper pots. A properly made newspaper pot will be durable, break down and cost you nothing but time. I learned how to make them from Meg Cowden of Seed to Fork. There are other paper pot options, but this folded pot is the only one that seems durable enough to last as long as you need it. I stopped making paper pots only because it was time consuming and because I ended up with too many paper cutouts.
If you’ve been thinking about seed packets , I should mention that I tried them and found that they didn’t work very well. A few years ago I thought I had found a great, inexpensive solution to potting plants that could be planted outside in a bag! But I found them difficult to plant in, they fell over easily and were never the right size. I would hold off and choose one of the other solutions I described above.
Repotting may shock the plants, so be careful.
Many plants, such as poppies, cucumbers and loofahs, do not tolerate entangling of their roots well; in such cases, you should start the seedlings as close to planting time as possible to ensure that you only have to transplant them once (directly into the garden) or sow them straight away instead. Even for plants that don’t mind transplanting, like tomatoes, the process is still a shock, so be careful. There’s a lot that can go wrong here, and it’s usually human error. Remember that you will have to touch many plants, so if one seedling has a virus, disease or fungus, you are now using the same hands that touched that disease on all your other seedlings. Wash your hands frequently and do not transplant seedlings that look diseased. Throw them away (not compost) and wash your hands.
People usually grow more than one seed in a seed cell or block it in case one seed does not germinate. But it is so difficult for novice gardeners to release one of these seedlings if both seeds germinate, so they try to separate the seedlings and transplant each into a new pot. My advice is don’t do this. Part of gardening is preparing yourself to cull seedlings, and you should do this before you begin the potting process. If there are still several seedlings in the cell at this point, cut one down to the soil line and allow the stronger one to survive. This way you are not breaking up the soil around the roots and trying to separate them.
Remove the seedling from the tray as carefully as possible, keeping the soil intact. I don’t water in the morning when I plan to repot because the drier soil makes the process easier. You can press the bottom of the tray to slide out the seed tray cell, but this is where the soil blocks shine: since there is no tray, they are much easier to move around. You simply pick up a block and move it.
When it’s time to repot, fill each pot with 2 inches of soil, then carefully place the seedling in the center of the pot. Use your hand to mound additional soil around the seedling block. Pat the soil down and give the seedling a sip of water, about a quarter cup. From there, the pot can be placed on a tray and returned back to the light. If you keep your pots on trays, you can water them from the bottom if you want, but water will pool if you water from the top as well.
Remember that when you lift a pot, you erase any markings you had on the seed trays, so make a plan to mark the pots as you lifted the pot, otherwise you won’t know what’s in any of them.
You can correct leggy starts when climbing into the potty.
Some plants, namely tomatoes, can form roots throughout the stem. For this reason, when you move tomato seedlings or transplant them into the garden, bury the stem deeply. Increasing power is the way to do this, and it can solve the problem of long-legged starts. Eggplants, peppers, tomatillos, ground cherries, squash, squash, melon and potatoes can be buried deep in the soil along the stem.
However, you still want at least the top two leaves to appear above the soil line. You should remove all stems and leaves below this point and then bury the stem to the appropriate depth and proceed as above.
How to water plants in pots
You will feel great at this stage of the seedling process. Your plants are established, look like the real thing, and you’re waiting for the ground to warm up enough to replant them. However, be careful because in my opinion this is when they are most vulnerable. They are still inside with limited air flow and in close proximity to each other. The virus and fungus can spread quickly, and light is limited due to all this new growth.
Be careful to water enough, but not too much. For this reason, I prefer to water from below, which means you pour about an inch of water into the trays the pots sit on and allow the plants to absorb the water they need, but no more. I don’t recommend watering from above because you don’t want the leaves to be wet, which creates conditions that make disease more likely to spread.
Plants also need feeding now, so no matter how you water, be sure to add some fertilizer to the water. For this purpose, I like Fox Farm vegetable fertilizer . Follow the instructions on the bottle and you’ll be fine.