How to Grow Incredible Tomatoes 

Posted by Margaret Hoegg on

Tomatoes have been called the gateway plant to serious gardening. For many, a fresh, ripe organic garden tomato is an irresistible incentive to learn how to grow healthy tomato plants for flavourful fruit and abundant yields.   

Tomatoes are quite easy to grow from seed (shop our tomato seeds here) and each plant yields on average 25 lbs of fruit. They’re also very simple to freeze or can in a hot water bath, so that you can enjoy the tomato harvest all year long. Check out our Canned Late Summer Salsa recipe for some canning inspiration.

For gardeners and farmers, every growing season is different and comes with its own set of challenges - a wet season could lead to fungal disease; a period of drought could cause splitting and sunscald; a pest-free year could be followed by an infestation. So what can you do to encourage healthy tomato plants?

  • Learn how to build healthy, soil
  • Learn to identify common diseases, disorders, and pests 
  • Focus on prevention


These are the best gardening tools to have with you as you grow the best organic tomatoes of your life this year!

Starting Tomato plants from seed 

One method to optimize water uptake in your tomato patch is to build strong root systems  and then plant your transplants deeply.

We start our tomato seeds in a bit of soil at the bottom of a makeshift pot, usually a milk cartons scored from a local cafe. As the tomato seedlings grow, we pinch off the lower leaves and add more soil. We continue this process until the soil level is flush with the top of the pot. This allows for your transplants to develop massive roots. 

 

Transplanting tomato seedlings

You’ve seen the little white hairs on the stem of a tomato? Each one is a potential root. When you bury them, they begin to grow.

So after a Spring focusing on growing tomato roots, we plant them deeply in the garden. The hole you dig depends on how tall your tomato plant is from the very base of the root, to the bottom of the leaves. For us, the root is the depth of a milk carton, so we dig our holes to one foot. Think of that root’s ability to expand and to collect water from deep in the Earth, all Summer long.

Building healthy soil for tomatoes

We’ve said it before and we’ll keep on repeating it: healthy soil is the most important ingredient for healthy plants. The best way to keep your tomato plants disease-free and pest-resistant is to ensure the soil has plenty of organic matter, balanced nutrients and healthy soil microorganisms. Biologically active soils, with regular inputs of compost and cover crops, provide all the nutrients tomato plants need to thrive. 

Tomatoes do best in well-drained slightly acidic soil, with some nitrogen. Too much nitrogen will encourage foliage over fruit; a shovelful of compost per plant should do the trick. In Spring and Fall, before transplanting seedlings and following harvest, plant a cover crop - like white clover (image above) - in your tomato bed to increase soil fertility. 

Caring for your soil will help it to become naturally disease-suppressing to support strong, healthy plants. 

A note on watering tomatoes

Conditions like yellowing leaves, cracking or splitting fruit, and sunscald all stem from issues related to watering. Tomatoes do need a lot of water, but they can handle long dry periods because of their large root systems. It is best to water tomatoes deeply once a week during dry periods. 

If soil moisture is too inconsistent - for example if you overwater after a dry spell - the fruits can crack or plants can develop blossom end rot (we’ll get to that soon).

It’s best to avoid watering the leaves at all to prevent fungal disease. If you feel the need to apply a foliar spray such as seaweed or compost tea to boost general disease resistance, do it in the morning so any moisture on the leaves has time to slowly evaporate throughout the day. Watering any plant in the heat of the day can lead to sun burnt leaves! 

Mulch your plants to conserve moisture in the soil, reduce weeds, and also keep watering from splashing up onto the leaves. If there are leaves touching the soil, remove them. 

Common tomato diseases and disorders

Preventative care is the best way to deal with disease, which is why the simple act of paying attention is an important part of your work as a gardener. When you recognize early signs of disease, there are still things you can do to prevent it from doing further damage to your plants and soil. 

Make a habit of strolling around your gardens once a day to inspect plants - who doesn’t want a garden stroll on their to-do list anyway? 

There are many possible diseases in the nightshade family (which tomatoes belong to), and there are some great books and resources out there that dive deep into these topics. This is by no means comprehensive, but these are a few of the most common diseases and disorders in tomato plants. 

Tomato Blight

Blight is a common fungal disease that can affect the stems, leaves, roots, and fruit of tomato plants. Early blight and late blight are quite different beasts to contend with.

Early Blight

image from https://extension.umd.edu/hgic
Early blight first shows up as brown spots with a yellow halo on lower leaves. When it affects the fruit, it appears are sunken brown spots near the stems. Early blight thrives in damp weather - it can be in the soil and can overwinter of diseased plants left in the garden the season before. 

Despite its name, early blight can appear at any time in the season. It won’t necessarily kill a plant, but it can weaken it and diminish yields. It isn’t nearly as devastating as late blight. 

Late Blight

image from www.gardeningknowhow.com

Late blight is fast-moving and absolutely bad news. It’s airborne and highly contagious, which means the spores can travel between neighbouring gardens. It thrives in warm, wet weather with cooler nights and shows up mid to late season. You might first notice dark scorched spots on leaves, but these spots quickly grow and spread, turning plants almost black. 

If you notice late blight on your plants, you should remove infected plants immediately. Do not leave any plant debris in the area and do not add it to your compost pile. 

How to prevent fungal disease:

  • Improve airflow around your plants 

    • pinch suckers or side shoots

    • stake or trellis plants

    • remove leaves that touch the ground 

  • Don’t let water splash on leaves

  • Practise good sanitation

    • keep your hands and tools clean when dealing with diseases such as blight. 

    • don’t compost diseased tomato plants and don’t dig them into the soil. 

  • Practice crop rotation 

    • rotate your nightshade crops for three years, if you can 

Sometimes nutrient deficiency and fungal diseases can look the same - yellowing leaves and spots.

Blossom End Rot

image from https://www.gardeners.com

Blossom end rot is not a disease, but a physiological disorder caused by stress, not pathogens. It indicates a calcium deficiency in the fruit, which could be caused by inconsistent moisture in the soil, root damage, or excess nitrogen in the soil. 

It appears as a water soaked, rotten looking spot at the blossom end of the tomato fruit, when they are about half their full size. It is more likely to take hold when your growing season has a wet start and then a long dry period after plants set fruit. (Maritimers: Take note!)

The problem with disorders like this is that your plants may look fine and by the time they show signs of stress, it can be too late. If you see signs of blossom end rot, remove the damaged fruit. 

Common Tomato Pests

There are quite a lot of pests that are drawn to the nightshade family, which tomatoes belong to. It's important to know how to identify not only pests, but also the damage they can cause. You will often see the sign of the pest before you see the actual creature! 

If you do spot an unidentified insect, don’t panic. There are plenty of beneficial insects that might visit your garden, and you don’t want to kick them out. 

Tomatoes can handle up to twenty percent defoliation without impacting yields, and there aren’t many insects that can do this level of harm. However, there are a few culprits that can kill plants, especially when they are still vulnerable seedlings. Here are some of the common threats:

Cutworm

Nails protect vulnerable seedlings from cutworm damage - image from https://montanahomesteader.com

Cutworm larvae are fat little grey/brown caterpillars that you’ll likely find curled up in your soil. They feed at night and burrow during the day. They mature into brown moths, which pose no direct threat to your garden, but will lay hundreds of eggs on leaves and stems. 

Their larvae can hibernate in the soil or in piles of garden debris over winter - another reason to clean up your Fall garden! They mature and start feeding in Spring. 

Cutworms feed on plant stems - if you find your plant stems have been chewed or cut neatly below or at ground level, cutworms are the likely culprit. They can chop down a whole row of tomato plants overnight! This can be heartbreaking, especially if you’ve just planted out precious transplants that you’ve grown from seed.

A few tips to prevent cutworm damage

  • Drive a nail alongside the stem, so that they can’t wrap themselves around the stem.

  • Make cardboard collars for around stem - dig them into the soil an inch or two

  • Time your seed starting strategically so that your plants will have thick, strong stems when you put them out

  • Don’t put out your transplants too early - cutworms do most damage in early Spring

  • Turn your soil in Fall to let birds (or backyard chickens!) feast on the larvae

  • Clean up any garden debris in the Fall

  • Note: cutworms love to feast on grass and weeds, so brand new gardens are more susceptible to these pesky pests

Hornworm

Tomato Hornworm - image from https://extension.umd.edu/hgic

Hornworm are quite large, but they are masters of disguise - camouflaging their long, pale green bodies against tomato stems and leaves. You can identify these green caterpillars by their seven white stripes and telltale black or red horn on their rear. 

Hornworm can be quite destructive, but if caught early and hand picked, you shouldn’t need to take further measures. You really must take a close look at your plants to spot these, so be vigilant! Be sure to check on the underside of leaves for green eggs as well. 

The best way to control hornworm is to handpick them and drop them in a bucket of soapy water. 

If you feel overwhelmed. . . 

When it comes to tomato diseases, disorders, and pests - an ounce of prevention is worth a pound of cure! You will learn something new every year - our gardens are always sending us new challenges and opportunities for learning, right? If you feel overwhelmed by plant care, just remember to bring it back to basics - high quality seeds and plants, healthy rich soil, and organic practices. 

Happy gardening!


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2 comments

  • Hi Micheline & Louis,

    I’m so glad you were able to find some help in this article!

    Too bad about your rough start this year. It was tough here in Nova Scotia too! Very cold & wet, with lots of heavy downpours. It was a while before we could get things into the ground…

    One of our go-to books is “The Organic Gardener’s Handbook of Natural Pest & Disease Control” by Barbara W. Ellis & Deborah L. Martin. It’s pretty complete, with pictures, so you can compare different possibilities with what is happening in your own garden. :)

    Thanks for spending time in our library!

    Hilary
    Incredible Seeds

    Hilary Mueller on
  • Hi Chris and Hilary, We were devastated my husband and I last spring when we found our new tomatoes plants dead in the house . We found that they catch damping off, I lost mostly half of them. I had at that time 23 tomatoes plants now in the garden, only 6 rest. By chance, I was able to save 4 plants of your famous Italian tomatoes . We lost 2 other with the cutworm. At that time we didn’t know what to do but with all the books we have, found the pest who did that and we have put milk boxes around, that was perfect.
    This morning I read in your library the same and more way to protect our plants. Thank’s to you we will save that part of the book. Hope next year will be a better year for gardening, this year is a mess almost all the plants have trouble to grow.
    So Guys, have a good summer and continue to give us inspiration for our growing season.
    Best regards
    Micheline Leclerc and Louis Drolet
    New Glasgow PE

    Micheline Leclerc on

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