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Buying Healthy Tomato Plants: What to Avoid

Buying Healthy Tomato Plants: What to Avoid
Home » Grow Your Own Food » Growing Great Tomatoes » Buying Healthy Tomato Plants: What to Avoid

I started selling heirloom tomato plants at the St. Paul Farmers’ market ( in Minnesota) in 2009, and every year I am fascinated with the care (sometimes bordering on angst) that people take in selecting their plants.

These tips on buying heirloom tomato plants should help next time you’re in the market for the perfect tomato plant for you, whether heirloom or hybrid.

Jump to: Signs of Healthy Plants | What to Avoid

Tomato seedlings in 4” pots ready to plant out
Tomato seedlings in 4” pots ready to plant out

Before moving to Minnesota, my husband and I ran a small Christmas tree farm in Oregon, and the process of selecting the perfect tomato plant is strikingly similar to finding the perfect Christmas tree. 

Some people will spend a good part of the day worrying about details that only they can see, and some will just turn to me and say “pick me out a good one”.

In the end, the perfect plant is the one that will fit your specific growing conditions.

In an attempt to make your life a little easier, here are a few “dos and don’ts” for buying heirloom tomato plants.  Understand, I’m talking about healthy plants.

The amount of tomatoes you get, the size of the tomatoes, whether they are early or late, and how they taste is dependent on the variety and your growing practices.  For tips on selecting plants based on specific flavors, review this guide on heirloom tomato flavor profiles.

The following list is  just a set of tips for making sure your plant grows into a healthy expression of what it’s genes tell it to be.

Signs of Healthy Tomato Plants

Here are 7 key factors to look for when purchasing a tomato plant at the nursery or farmers’ market:

  1. Make sure the size of the pot is in proportion to the size of the plant; if you have a large plant in a small pot it is likely to be rootbound.  I think the perfect pot size is a 4″ pot, as it has allowed the plant to gain height while comfortably spreading it’s roots.  The example of the taller plant above is a 12″ plant in a 4″ pot.  While some plants may be shorter than this due to variety, they would still be best in a 4″ pot which allows their roots to grow gradually until you get it into the ground.
  2. Look for a fairly thick stem; tall plants with thin stems have been stressed trying to reach the light and they will not stand up well to wind and rain in the garden;
  3. Make absolutely sure your plant has been hardened off.  If you are buying it at an outdoor market, you will know by the fact that it is not drooping and wilting, but if you are buying from inside a nursery or a catalog…ask to make sure.  Plants can look extremely healthy in a cultured environment and will fall over and wilt if you plant them outside without being hardened off;
  4. Small white nodes along the bottom of the stem is not a bad sign (see photo below).  Those are trying to be roots.  Plant the tomato deep enough to cover those white nodes and you will get more roots, and more tomatoes;
  5. Look at the growing whorl at the top of the plant; the bottom leaves of the plant may have suffered while hardening off, but if the top whorl is green and growing well, that is the main thing.  You should plant your tomatoes fairly deep anyway and take off the bottom leaves if they touch the ground.  The stem and the top are the two most important signs of health.
  6. Check the underside of the leaves to make sure there are no aphids or small bugs you would be bringing home;
  7. The color of the plant should be green (with the exception of any bottom leaves that have suffered windburn or sunburn while hardening off).  If the plant is yellow it has probably been in the pot for too long and is lacking nitrogen; if the plant is somewhat maroon it has an iron deficiency.  Green is good.  You can fix the deficiencies with nutrition, but if it has gone too far the plant may be stunted;
White root nodes on stem of healthy tomato plant
White root nodes on stem of healthy tomato plant

What to Avoid when Selecting Tomato Plants:

  1. Do not get great big plants that already have small tomatoes on them.  They have already put a lot of energy into fruiting before their time and you will not get very many tomatoes from them.  It’s fun to see tomatoes so early on a plant, but you will pay for it later with a poor yield.
  2. In the same vein, try to avoid plants that have blossoms;  Early blossoms on a small plant means it has been stressed and feels it must hurry and produce.  The yield will be poor.
  3. Small pots with large tomatoes will most likely mean the roots are tangled up into a ball in the pot.  If you get one of these, be sure and break the roots gently apart and spread them out when planting;
  4. If you are going to grow your tomatoes in pots, ask for a variety that is determinate and you will likely have more success.  Indeterminate plants will vine until frost and it is difficult to keep them upright in a pot without them breaking over the cage.  A determinate plant will grow to a certain height and stay relatively stocky.  With a determinate you will get a large yield over about a 3-week period, whereas with an indeterminate plant you will get a smaller yield but over a longer period of time.  Not to say that you can’t grow indeterminates in pots…you can.  It is just easier with determinate plants.
Young tomato plant showing blossom.
Young tomato plant showing blossom.

Where to Buy your Heirloom Tomato Plants:

Lastly, try and buy your tomato plants from a farmers’ market or somewhere where you have access to questioning a grower familiar with how the plant has been grown.  The employees at many of the big box home stores may not be the best resource to help with any tomato questions you may have.

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