What to Know Before You Plant Tomatoes (to Avoid Mistakes)

New to growing tomatoes? These tips from an experienced gardener will help you avoid common mistakes. Whether it’s heirlooms or hybrids, determinates or indeterminates, smart preparations will make all the difference.

For all the basics, also see Tomato Growing Tips for Beginners.

Tomato Growing For Beginners

If you’re a beginner gardener ready to grow your first tomato plants, you’ve come to the right place. I’ve made all the mistakes so you don’t have to.

There’s a few basics to know to ensure you will have a delicious harvest of fresh tomatoes and avoid some common problems that can happen along the way.

I’ve kept it simple, so you can check the list, know what to expect, and start growing.

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Contents

• 10 Best Tomato Growing Tips
  • Start With Healthy Plants
  • Know What You’re Growing
  • Wait For Warmth
  • Provide a Good Foundation
  • Choose a Sunny Location
  • Set Up Supports Before You Plant
  • Learn About Suckers & Pruning
  • Be Prepared to Water Daily
  • Know What Blight Is
  • Tag Your Plants
• Resources

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10 Best Tomato Growing Tips

Here are some helpful tips to know before you plant tomatoes. Some involve advance preparation; others let you know what to watch for along the way.

1Start With Healthy Plants

You can buy starter plants or start your tomatoes from seed.

If you are a new gardener, it’s not always easy to assess the health of a plant at a garden nursery. You may want to ask for help. But choose your advisors carefully. I’ve shopped at nurseries with knowledgeable, honest staff who notice infected plants and remove them. But I have also visited plant nurseries with diseased plants where staff pretended nothing was wrong. Not cool.

Sometimes it is obvious that a plant is in distress: the leaves will be yellowing or curling—not just one, but several— or the plant appears wilted and sickly. Other times the plant looks okay but there are actually insects under the leaves or in the soil.

Have a good look at the plant before you purchase it, and, if you have any doubts, don’t buy it.

Another common problem is when plants have been pampered in perfect greenhouse conditions that we can’t replicate at home. If changes are too abrupt, the plant can struggle and delay growing time. Pay attention to the home the plant is coming from and what your planting location has to offer. If needed, make the transition gradual using this “hardening off” process.

If you want to start your tomatoes from seed, assuming you’re in a cold climate like I am with a frost-free growing season from around May to September, you will need to start your seeds indoors weeks before last frost in spring.

Starting your own seeds also offers way more seed choices than garden nurseries can provide.

I have an indoor seed sowing plan here and complete instructions starting plants from seed indoors here.

2Know What You’re Growing

There are many varieties of tomatoes to choose from.

Should I get heirloom or hybrid tomatoes?

There are benefits to both:

• Some of your favorites may be heirlooms with the added benefit that you can save the “open-pollinated” seeds for planting next year.
• Hybrids tend to be very reliable growers and disease-resistant, but you do need to buy new seeds each year (or buy starter plants) if you want to be sure they will grow as promised.

Try some of both! I like to grow a few old favorites plus some new varieties each year.

The type of seed is not often mentioned on the plant tag and you may need to ask the vendor. Bigger nurseries and chain stores usually carry hybrids. Smaller and independent growers may sell heirlooms and hybrids.

This explains more about hybrid, heirloom, and open-pollinated seeds.

How big will the tomato plants grow?

• Bush tomatoes (also known as determinates) max out at about 3 feet tall and wide. These tomatoes ripen all at once at the end of the growing season.
• Semi-determinates are bush tomatoes that provide a second harvest.
• Vine tomatoes (also known as indeterminates) continue growing until the cold weather sets in. They can last for years in greenhouses. These tomato plants can grow 6 feet and more, and they provide a continuous harvest once the first fruits ripen.

Is there enough time in your growing season?

• Check the plant tags for the ‘number of days to maturity’ and allow two weeks extra for normal delays like cool weather.
• Compare that number to your number of frost free days plus indoor growing time.

Are there enough days for the tomatoes to grow and ripen before then?

Keep in mind that growth and ripening slows as the days shorten and grow cooler so you may need more time than specified.

This answers When is it too late to sow seeds outdoors?

3Wait for Warmth

Tomatoes are warmth-loving plants.

• If you have purchased tomato plants before the last frost of the season (in your area), hold off planting and keep them watered in a sunny, warm indoor or sheltered location.
• The soil is generally warm enough for planting outdoors about two weeks after last frost.

If you’ve been coddling your tomato plants or seedlings indoors, be sure to transition them gradually to life outdoors using this method.

4Provide a Good Foundation

You can plant tomatoes in containers or in the ground.

• If planting in containers, use organic container mix suitable for vegetables. Containers offer the advantage of being able to move the plants around as needed. You may also need a liquid organic fertilizer, such as kelp or fish emulsion, every few weeks throughout the growing season.
• For container size, I like the pot to be at least a foot deep and wide—and larger is possible—per plant.
• If planting in the ground, make sure your soil is rich in organic matter and allow room for growth, keeping in mind that many tomato plants end up 2-3 feet wide.

5Choose a Sunny Location

Ideally, tomatoes should get full sun for at least six total hours per day—eight is better.

They will still grow with less sun, but the shadier the conditions, the longer it takes for the fruit to ripen and you may run out of time before fall sets in.

Too much heat can cause the flowers to drop off, which means no fruit.

6Set Up Supports Before You Plant

If you’ve ever tried to train a mature tomato plant, you know how hard it is. Once they have branches and leaves, it’s nearly impossible to get them into support cages or trellises without damaging the plant.

It’s much better to set up the supports at planting time and continue to tie them as they grow. Otherwise, any strong winds, rain, or handling can break off the fruiting branches.

The more heavy-duty your supports, the better. I have a tutorial here for making tomato cages from wood. You can also use cattle or hog panels (welded grid metal sheets, often sold in 16-foot lengths) or other rolls of welded metal. Every gardener comes up with their own preferred way.

7Learn About Suckers and Pruning

Tomato plants have 3 basic parts: the main stem, stems with leaves, and suckers. All of these are natural and normal. The stems and suckers grow little yellow flowers that gradually morph into fruit (tomatoes).

Pruning is a hot topic with gardeners. Some swear by it, others do not not.

I think it depends on the characteristics of the specific plant and your growing conditions.

In general, bush-type tomato plants (determinates) do not require pruning. They form their fruit at the end of their branches, and you do not want to decrease fruit production by removing stems with flowers.

Vine tomatoes (indeterminates) can become unwieldy and prone to breakage. To prevent problems, it’s advised to have 4-5 fruiting stems and prune away the rest.

This has everything you need to know about suckers and pruning tomatoes.

8Be Prepared to Water Daily

Tomatoes require consistent moisture levels and are not good vacation plants.

Check your tomato plants daily and more often during heat waves, or set up a drip irrigation system.

A layer of straw mulch can also help keep moisture in (and some pests out).

Warm water is best. If you fill your watering can after each use, the water will be warm and free of chlorine by the next day although it’s considered safe to water soil directly if it is less than 5 ppm. Your local water treatment facility likely posts this amount somewhere online.

What happens if watering is uneven?

• Uneven watering can cause the flowers to drop off, and have some correlation to conditions like blossom end-rot.
• Sometimes excessive rain will actually cause the fruit to crack open.
  This explains more about tomatoes splitting open on the vine and how to deal with it.

9Know What Blight Is

Yes, blight and other diseases happens. Blight (early or late) is caused by a fungus that causes the tomato plants to wither and die.

There are also various types of tomato wilt. The fun never stops.

It’s good to be aware of these things so you can catch them early. If you suddenly notice your plants don’t quite look right, do some Googling and see what it might be. Also check with gardening friends in the area to see if they are experiencing it too.

Sometimes, if you act early, you can prevent the spread, and, in some cases like blight, even if the plants look terrible, the fruit may be unaffected and still edible, though you still have to properly dispose of the affected foliage.

There are also intriguing beasts like the tomato hornworm to keep things interesting.

10Tag Your Plants

Be sure to tag your plants so you know what’s what and can track each variety by name. This way you’ll learn which varieties grow nicely in your garden and taste delicious. This is the tagging method I use for tags that never fade, rust, and last for years.

If you just want to write plant tags with a long-lasting marker, this shows which type of marker paint pen to buy.

If you grow some heirloom varieties, plan to set aside some of the ripe fruit for seed saving. This tells you how to save heirloom tomato seeds. I can’t tell you how many times I’ve accidentally eaten everything and then remembered this too late!

Hybrid seeds provide excellent plants as well, but the seeds may not be reliable for saving. You can still save them but the next generation of fruit may be different than the previous one. That is no big deal to me.

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Resources

Mark your calendar for next year—seed starting should begin indoors a few months before last frost.

~Melissa the Empress of Dirt ♛