There will come a time when your seedling plants will need to be transplanted into larger containers to promote healthy growth. This is the final major step before their exciting big move outdoors. We just started transplanting some of our seedlings today, which is at least a month before we’re planning to plant them in the garden beds. This is the point where you feel a big sense of accomplishment because your tiny seedlings finally start to look like real vegetable plants. Just imagine the taste of all of those fresh veggies straight from your garden this summer!
Why Seedlings Need to Be Transplanted
- They need a richer growing medium to help them grow before they’re planted outdoors. If you’re growing an organic garden, a rich organic potting soil is a good choice. (Here is an example.)
- You know the feeling you get when you’ve been riding in a car for a long time and you need to stretch? That’s exactly what happens to the seedlings. They need more space for their roots to spread out and grow, and the plants themselves start to get cramped and compete for light in their original flats.
- Extra seedlings need to be thinned out to avoid crowding. If you planted more than one seed in each furrow, as we did, the plants need to be thinned down to one per container.
When to Transplant Seedlings
As we speak, we’re watching our seedlings for their second set of “true” leaves, and also for crowding in the flats as signs to transplant them. The seed leaves are the first leaves to form right out of the soil. The true leaves are the ones that form after that, and in most cases they look more similar to the adult plant’s leaves than the seed leaves do. Once the true leaves open up, there’s a good chance your plants will become crowded really quickly.
Types of Containers
A 3″ to 4″ pot is a good size for transplanting seedlings. Yogurt containers with holes punched in the bottoms are an option, as are DIY newspaper cups. We used 3″ peat pots (here is an example) and newspaper cups. The convenience of these two options is that you can plant the pots straight into your garden without having to remove the plants. To make a newspaper pot, double up a piece of newspaper and cut it to about 8″ x 4″, then wrap it around a round glass and tape the sides together. Tuck in the bottom edges, then slip it off of the glass.
How to Transplant
It helps to water your seedlings to soften the soil a bit before transplanting them. We planted our seeds in individual soil blocks, so I just lifted each block out and very gently loosened the soil around the seedlings using my fingers. You’ll see very fragile roots and you’ll want to be as careful as possible to not break them apart too much. We filled the pots halfway with potting soil and set a seedling on top of each, without compressing the fragile roots. It’s easiest to fill the pots ahead of time to have them ready for the seedlings as soon as you lift them out of their flats. Finally, we tucked soil around the plants, adding another inch or so of potting soil. We watered each one so that the soil was moist but not soggy.
- Continue to give your plants at least 12 hours of light per day, making sure to raise your grow light as they grow taller. We keep our light a few inches from the tops of the plants.
- Just like before, water them to keep the soil just moist but not too wet. Setting your pots close together in a tray or flat will help them retain moisture.
- If your organic potting soil doesn’t contain fertilizer, you may want to consider fertilizing your seedlings after transplanting. Fish emulsion (like this one) works great; just make sure to check out the directions and use it at 1/4 strength.
Have fun watching your plants really take off now that they have more room to stretch out, and enjoy them indoors until 2 weeks before your outdoor planting date. My next post in this seed starting series will be about hardening off the seedling plants.
Other posts in this series:
- How to Start Seeds Indoors
- Starting Seeds Indoors: What to Do When They Sprout
- Moving Your Seedlings Outdoors
- How to Give Seedling Plants a Strong Start in the Garden