How to Care for your Tomato Seedling

Tomato varieties


Each year, we grow tomato seedlings (lots of different neat varieties!) for our customers to grow in their own backyards.

Every variety has been trialed and tested by us on our farm and has successfully ripened delicious tomatoes in our climate.

We start them from seed in March and grow them in organic potting soil with organic nutrients that we add for slow-release minerals so your tomato harvest will be tasty and nutritious.

Here are our tips for caring for them.  


Once you’ve brought your tomato seedling(s) home, it needs:

  • Protection from frost. They won’t survive a frost. The last frost-free date is never the same but typically sits somewhere between May 24th and June 5th in our region. It’s important to listen to weather forecasts for chance of frost. While your tomato seedling is still in its pot, you can move it indoors at night and back outside on warm days. Once you’ve planted your tomato seedling in the ground, the best way to protect your tomato plant from chance of frost is with protective blankets like row covers (you can purchase these at a garden centre) or old bed sheets. The benefit of row covers is that light can transmit through them so you can also leave them on during the day. If you use a bed sheet to protect the seedlings from frost, make sure to take it off in the morning – plants need light! Make sure that your tomato plant has some structure around it so the row cover or bed sheet isn’t lying right on top of the plant. You can use stakes, metal hoops, a homemade teepee, tomato cages, etc for this purpose and then lay the cover over top of that.
  • Sufficient Water. Tomatoes need enough water to live but they don’t like it when the soil is too wet for too long. Especially while still in their pot, make sure to not overwater your tomato. Many people wait until the tomato plant just slightly starts to wilt before giving the soil a good dose of water. Because tomato plants are susceptible to many fungal diseases on the leaves, it’s often recommended to water at the base of the tomato plant rather than sprinkling water over top of the whole plant. If you do water over the whole plant, it’s best to do it when the plant’s leaves will be able to quickly dry out again, like in the morning of a sunny or breezy day. Of course, there’s not much you can do when it’s raining outside unless your tomato plant is in a greenhouse or plastic hoophouse.
  • Sufficient light/sunlight. If you’re keeping your tomato plant indoors or on a patio, you want to make sure there’s a lot of light that will reach the plant. If there’s not enough light, you’ll notice the plant stretching to try to access light (this is known as getting “leggy”). If you’re planting the tomato in a garden outdoors, you’ll also want to make sure it’s a sunny site. If it’s not a sunny or hot enough garden spot, rather than getting leggy, your tomato plant will probably grow quite nicely but you may not get many ripe tomatoes.
  • Food. If you’re planting your tomato plant into your garden, the food will come from the soil. There are uncountable amounts of micro-organisms in the soil that collaborate underground to help plants get the nutrients they need. You can help them along by adding some good quality compost to the soil before planting (or even after planting, on the soil surface or lightly raked in next to the plants). Keep in mind that too much nitrogen (from manure or other nitrogen-rich amendments) will likely make your tomato plant grow big and beautiful but not produce many tomatoes. If you’re keeping your tomato plant in a pot or planter box, you’ll need to add food, again in the form of compost. And, you’ll need to make sure you plant your tomato seedling in a container that’s big enough for it to grow and get enough food (which will all be in the soil in the pot).
  • Space. In a garden, your tomato seedling will need at least a foot of space around it. If you’re planning on pruning your tomato plant (for indeterminate varieties only) you can get away with less space than if you don’t prune (which may require 2 feet around the plant). If you’re container growing, you’ll need to move your tomato seedling into a larger pot as it grows. When we’ve grown tomatoes in containers, we used 1 gallon pots.

Tomato plants


Planting your tomato seedling in the ground or in a larger pot:

  • Hold your pot tipped upside down in the air and “catch” the soil (which should stay all together…ideally you should water it first so the soil is moist) in your hands. Don’t pull on the stem in case you break it.
  • Make a hole (either in your garden or in a larger pot) that’s large enough for the whole soil block. Some people swear by planting the tomato seedling as deep as possible…even so you can only see the top few leaves. Tomato stems that are buried will grow more roots along the stem and so this can help the plant be sturdier in the ground. On our farm, we plant our tomato seedlings at about the same level as they are in the pots, maybe just a tiny bit deeper. This is because, when you plant a tomato plant deeper, it spends time working on growing roots out of the now-buried stem. And we want it to focus on just rooting into the soil and growing new leaves so it can work on the tomato fruits faster. But we’ve grown tomatoes both ways and they both have been successful for us. I wouldn’t worry too much one way or the other if I were you. Do whichever you like. If however, your garden site is very windy and there’s not much of a windbreak for your plants, you may want to do the deep stem burial so the wind doesn’t snap the stem. The plant will adjust to its new (windy) site and grow stems that are strong to anticipate the wind.
  • If you choose to bury your tomato seedlings, here are some resources: How to Transplant Tomato Seedlings and Planting Tomato Plants on their Sides.


Supporting your plant:

  • The purpose of supporting your tomato plants (often referred to as Staking or Trellising) is to keep the plants up off the ground. This reduces disease and pest issues in tomatoes and makes it easier to see and harvest your tomatoes.
  • How you support your tomato plants will depend on whether the variety you chose is Determinate or Indeterminate.
  • Determinate means the variety of tomato plant has a pre-determined size that it will grow to. It will typically produce most of its tomato fruits within 1-2 weeks. Determinate tomatoes are also referred to as Bush types. Some people don’t support these “bush” tomatoes at all while others will use tomato cages or stakes to keep them upright.
  • Indeterminate varieties will grow until they’re killed by frost and produce fruit for a longer season. They are often referred to as Vining Tomatoes.
  • Determinate/Bush types don’t necessarily need support but ideally they would be supported by stakes, or tomato cages, or tomato boxes (stakes around the outside with twine holding the plant inside). Indeterminate/vining types will need more support, something to grow up or along. A trellis of some kind works well. You can also do a technique called basket weave (or Florida weave).
  • For some ideas/inspiration on how you’ll support your tomato plant as it goes, check out: 32 DIY Tomato Trellis & Cage ideas for Healthy Tomatoes, or How to Trellis Tomatoes for Maximum Yield
  • For pruning tips, check out: How to Prune Tomato Plants.


Pest and Diseases

  • On our farm, diseases are a bigger concern for tomato plants than insect or rodent pests.
  • There is a type of flea beetle that likes plants in the tomato family. It is tiny and black and makes small holes in the leaves. We rarely see much evidence of this flea beetle and we’re not particularly concerned when we do. It is a different species than the flea beetle that goes after plants in the Brassica family (arugula, kale, cabbage, broccoli, radish…).
  • There are so many diseases and disorders associated with tomatoes that, rather than list them, we’ll just list some resources for you to check out if you’re concerned with something you see on your tomato plant.
  • For help diagnosing what’s wrong with your tomato plant, check out these resources: Tomato Pests and Disease Problems, ID and Prevent 6 Common Tomato Diseases, Common Tomato Plant Diseases.


Hope this has been helpful for you and that your gardening season is fruitful!


Heirloom tomatoes

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