- When the seedlings first emerge, they have only a pair of equal sized leaves. These are the seedling leaves and nourish the plantlet until it has formed enough roots to support itself. The seedlings at this point have only one little root trying to work its way into the soil.
- Within a week or so after the plantlet comes up, it starts to form its first true leaf. When this first leaf is out and is about a half an inch around, it’s the proper size for transplanting. The reason for this is that it has now reached the stage where it has formed some roots, but not so many roots that you won’t be able to separate the little plantlets.
- Separate the plantlets by grabbing the one true leaf and gently using it to pull the plantlet out of the mix. Of course, you will ruin some but you will have plenty regardless. If your mix is too hard and the seedlings don’t come out easily, you can use a knife tip to break up the soil a little first. As long as your seedling has a root or two after you pull it out it will be fine.
- It is best to transplant one seedling at a time, especially with hybrid seedlings where every one may be different. But it is sometimes easier to transplant 3-5 seedlings at a time, and then thin them out at a later date.
Transplant about 25 or so out of the pot at a time, and save the remaining extra plants back in the sealed container in case anything goes wrong with the first batch.
What to pot them in
Transplant the seedlings into the same conditions you are removing them from. Use the same soil mix if possible. You can either put the mix in shallow trays and transplant the seedlings in little rows, or you can use regular seedling trays cut to fit your container which have separate little compartments for each seedling.
Using the tip of a pencil, go through your new containers and make a small hole for each incoming seedling, about ¼” deep and wide. Then gently pull up a seedling from the seedling pot and set it into the hole you made with the pencil. If it doesn’t fit then make your holes a little bigger. Repeat this process until you’ve transplanted as many as you want. Go back with your pencil, or whatever your favorite utensil is, and smooth around any that need it. You don’t want the roots exposed to the air, so just tuck them in a bit. After planting, give them a misting with the spray bottle as with the seed.
The important thing is to give the now transplanted seedlings a warm and high humidity place to adjust and begin to grow. Keep the transplanted seedlings in a sweater box or clear covered container, for at least two weeks or so. Keep labels on everything, so you don’t forget what each seedling is. Depending on what species or type of begonias you are seeding, at about 2 weeks after transplanting they should be ready to slowly adjust to lower humidity and increasing light levels and you can remove the lid on the container they are in.
If any start to die or rot, you have the mix too wet or not sterile enough, so open the lid a crack to let it dry out some. If that doesn’t work and they are still dying off, as a last resort spray them with a fungicide to try and kill the fungus problem the too wet conditions created. Don’t be discouraged if you have some failures. Count those as learning experiences and try again.