When To Transplant Tomato Seedlings From Seed Tray {Q&A}

Growing your own tomato plants from seed is a great way to save money and be sure of getting healthy plants. What are the best practices when growing tomato seedlings? When to transplant tomato seedlings from seed tray? How big should tomato seedlings be before transplanting? In this article, we answer these questions and more!

Transplanting Tomato Seedlings: Q & A

transplanting tomato seedlings: q & a

1. What is the best starting medium for tomato seeds?

It’s best to start out with a sterile commercial seed starting medium. Failing that, a very light and fluffy potting mix is a good choice. Stay away from heavy potting mixes because they retain too much water, encourage fungal growth and discourage high germination rates.

2. How much should you water newly planted tomato seeds?

Before planting seeds, moisten your starting mix to the consistency of a well-wrung-out sponge. Keep the soil slightly moist throughout the germination phase.

3. How deeply should tomato seeds be planted?

You should fill your seed trays or individual containers with your soaked potting medium. Press the medium down lightly and then simply sprinkle your tomato seeds over the surface of the soil. Press the seeds into the soil surface and then add a very thin layer (no more than a quarter inch thick) of light soil mix over the top. Press gently again.

You want to make sure that your seeds have good soil contact on all sides.

4. How can you keep the soil moist during germination?

Keep the soil lightly covered with plastic during the germination period. You can do this by placing entire seed trays or containers inside clear plastic bags or by simply laying plastic film lightly over the surface of the soil. Check daily and spray the surface of the soil with water as needed.

5. What’s the best temperature for tomato seed germination?

Place your prepared seed trays and/or containers in an area where the temperature will stay at about 70°F consistently. Be sure that the soil around the seeds stays a warm, consistent temperature.

You may need to add a heat source below the containers to achieve the best results. During the first few days of germination, your seeds will not need sunlight. You may want to place your containers on top of your refrigerator to maintain a warm, consistent temperature.

6. When do tomato seedlings need sunlight?

In a few days, your tomato seedlings will begin to emerge. When this happens, you should remove the plastic and move your seed trays and/or containers to an area that receives bright, indirect sunlight. When they develop their first set of true leaves, you can move them into direct sunlight.

If you do not have such a location, you can use florescent light or grow lights. Place the containers a couple of inches below the lights to encourage sturdy growth of the young seedlings. Light that is too far away will cause weak stems.

7. How much light do tomato seedlings need?

If your tomato seedlings are receiving natural sunlight, 6 to 8 hours a day will do. If you’re growing them under artificial light, they will need between 14 and 16 hours of light daily. Be sure to turn the lights off after this amount of time has elapsed. Your seedlings will need time to rest.

8. What temperature is best for tomato seedlings?

Once your seedlings begin to grow, they should have daytime temperatures ranging between 60°F and 70°F. Nighttime temperatures should be between 60°F and 65°F. This little dip in temperature overnight will encourage strong, sturdy plants. Excessive heat causes plants to grow leggy.

9. How can I be sure that my tomato seedlings grow strong?

Good air circulation will help your tomato seedlings develop strong, stocky stems. Set up a fan in the room with them. Turn it on low and place it so that it blows an indirect breeze around the area rather than having it blow directly on the plants.

10. How much water do tomato seedlings need?

Throughout their growth period, your tomato seedlings will need to have moist, not soggy soil. Check them daily to make sure that the soil feel slightly damp.

11. How should I water tomato seedlings?

Water very gently to avoid eroding the soil around the roots. Let the water sit out in an open bucket or watering can for twenty-four hours before using it. This will allow it to warm up to room temperature, and any chemicals in the water will evaporate into the air.

12. Do tomato seedlings need fertilizer?

Seedlings will not need fertilizer until they have produced their second set of “true leaves”. If your starting mix has some fertilizer incorporated, it will not hurt anything; however, early fertilizing is not necessary.

13. When should I transplant tomato seedlings from the seed tray?

When your seedlings have developed their second set of true leaves, it’s time to transplant and provide the first fertilizer.

At this time, you can transplant your seedlings into larger containers, or if the weather allows, you can transplant them directly into the garden. Apply half strength fertilizer at this time.

14. How big should tomato seedlings be before transplanting them to the garden?

Although you can transplant them directly into the garden as soon as they developed their second set of true leaves, many gardeners prefer to transition them through a larger pot or container before planting outdoors.

Let them grow to be at least 3 or 4 inches tall before planting outdoors. This gives them a little bit more time to gain strength and resistance against pests, diseases and inclement weather. It also allows the root system to develop and grow stronger.

15. Should I transplant all my tomato seedlings?

If you have simply sprinkled tomato seeds over your seed starting mix, you probably have far more plants than you really need. Cull out the week ones by snipping them at the soil line. Retain and nurture the larger, stronger ones.

16. How do you transplant tomato seedlings?

Whether planting your tomato seedlings in containers or directly into the garden, remember that the parts of the stem that are covered with soil will grow roots. This is a good thing because it ensures that your plant develops a strong, vital root system.

For this reason, you should plant tomatoes into deep containers and/or dig the planting hole deep enough to cover the stem right up to the first set of leaves.

Handle the plants gently throughout the process. Hold them by their leaves rather than by their stems. If leaves are damaged, they can grow back. Damaged stems will kill the plant.

17. What kind of soil should I use to transplant tomatoes?

Surround the plant and the part of the stem that is submerged with the same type of soil mix you used when starting your seeds. If you are planting into a container, purchase a good quality potting soil or container mix for the rest of the soil in the container.

If you are planting directly into your garden, be sure the soil is well tilled, light, airy and well draining. Amend it as needed to attain the correct pH levels and improve nutrient levels. Talk with your county extension agent and have your soil tested to determine exactly what is needed.

18. How do you take care of freshly transplanted tomato seedlings?

During the first week protect your seedlings against harsh sunlight and high winds. Keep their soil consistently moist, and fertilize on a weekly basis with a diluted fertilizer solution.

How To Transplant Tomato Seedlings

Nicky Ellis
Nicky has been an editor at Farm & Animals since 2019. Farm animals have been in her life from her earliest memories, and she learned to ride a horse when she was 5. She is a mom of three who spends all her free time with her family and friends, her mare Joy, or just sipping her favorite cup of tea.

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