Growing tomatoes from seeds is a fun and rewarding experience, and they grow pretty fast, too. One of the trickier things about it, though, is knowing the perfect time to transplant tomato seedlings into your garden.
There are many factors to think about when figuring out when is the best time to transplant your tomato seedlings. Here’s everything you need to know.
Table of Contents
Starting from a Seed
In many climates, it helps to start tomato seedlings indoors to avoid having to wait until the outdoor temperatures get warm enough for germination. Some people who take this route choose to grow multiple seeds in one pot, pulling those that don’t grow as much to ensure that only healthy plants are transplanted later.
But even if you take this route of ensuring you’re only planting the strongest seedlings, you still have to know when is the best time to transplant them.
Generally, you should plant to transplant tomato seedlings about six to eight weeks after you plant the seeds. To determine the specific time, plan to transplant them after the date of the last frost. For best results, wait until the outside overnight temperature reaches 50 degrees (10°C).
How Big Should Tomato Seedlings be When Transplanted?
Size is important when transplanting tomatoes because if you want too long, the roots may outgrow their seed tray which can cause problems for the plant’s future growth.
While you can transplant seedlings directly from the seed tray into the ground, some people find it beneficial to move the seedlings to a larger pot when they are between two and four inches tall.
Moving them to a larger pot before transplanting them to the ground gives the plants a chance to develop a more robust root system. When the plants are about 10 inches tall in the larger pot, transplant them into the garden.
Hardening Off the Seedlings
Before you transplant your seeds outside, you must take the time to harden them. This process prepares the plants for being outdoors after growing indoors. Hardening the seedlings takes a little time, but in the end, you get stronger, more resilient plants.
Start hardening the seedlings a week or so before the last expected frost.
On day one, take your seedlings outside for two hours in a place where they won’t get direct sun. Then, bring them back inside. Leave them outside in the shade for a longer period every day, continuing to bring them in at night.
One they spend most of the day in the shade, begin to expose them to a little more sun. Eventually, they should tolerate direct sunlight, but don’t immediately stick them in the brightest spot of your yard. Start with northern or eastern exposure for the day, continuing to bring them in every night.
Monitor the seedlings. If they are suffering, move them back into the shade and move a little more slowly exposing them to bright light.
Continue this process until the overnight temperatures stay above 50 degrees (10°C). When they’ve spent the whole day and night outdoors and can tolerate six to eight hours of direct sun and some harsh rain, it’s time to transplant!
How to Transplant Tomato Seedlings
For best results, wait until a cooler day that’s a little overcast to transplant your tomato seedlings. This will help prevent stressing them too much throughout the process.
Water the seedlings first, then lift them out by the leaves. Avoid pulling on the stem. The stem is easily damaged, which can kill the plant, but it can always grow new leaves.
The hole should be able to accommodate the seedling up to its second set of leaves. Everything under the soil grows roots, so this is a good way to make sure that the root system grows deep and supports the plant.
Space the plants at least two feet apart as their roots spread widely, and you don’t want there to be too much competition. Water the seedling gently, and use fertilizer as recommended by the brand you choose.
Tomato seedlings need cages to support them as they grow, and it’s safest to place the cage when the seedlings are young to avoid root damage and encourage them to use the cage as they grow.
Other Tips and Tricks
After you have your seedlings transplanted, they still require a lot of care and attention. Here are some tips that can help bring you success:
- Water your seedlings in the morning instead of the afternoon or evening. This makes sure that they have enough water to get through the hottest part of the day without risking the soil being too moist overnight.
- Add compost to the seedlings every few weeks once they begin producing fruit. The more nutrients they get, the better they will produce.
- Check your plants every day to make sure they are getting enough water and check for any signs of pest or disease.
Now that you know a little more about when is the best time to transplant your tomato seedlings from a seed tray, you’re well on your way to having a great harvest. Don’t forget to harden the seeds, and transplant them to a larger pot first to ensure that they’re strong enough to thrive.