Don't Make These 8 Tomato Planting Mistakes This Spring - You'll Regret #4!

The world’s favorite fruit vegetable is also very popular with amateur gardeners; you will find tomatoes in most back yards in all continents – but why don’t they always look healthy and strong? Why do you get black patches on them? Why do crops fail so often? The answer is that many people make the same mistakes with this plant – and most of them happen in spring. And then it’s too late to correct them.

For a long and bountiful crop of red and juicy tomatoes later in the season, there are 8 mistakes you must avoid at all costs. This plant is quite picky, and, despite its strong looks, it can be delicate. So, know now what to avoid and you won’t regret it later!

Mistake 1 – Planting Tomatoes in Poorly Drained, Compact Soil Without Any Preparation!

A common mistake to make with tomatoes is not to prepare the soil well. These plants like fertile soil, and a good layer of compost will sort this out for you when you transplant the seedlings. But how about drainage?

A woman transplants a seedling from a pot into the ground. Planting tomato seedlings in the hole.

Tomato plants drink a lot, depending on their size, and type of bed, they can need up to a whole gallon of water every day (4 liters)! But then, if your soil is not very well drained, or it is too compact, it stays there, around their roots, and they may catch fungi or / and rot away.

You may not realize it at first, but later in the season, your tomato plants will weaken and even die…

You can till the soil or use a decompactor before you plant the seedlings, but this will only improve drainage in the first stage of your tomatoes’ growth. But you also need to add coarse (gardening) sand, to make sure that the ground does not revert back to poor drainage.

However, if your soil is heavy clay, you will need to add gypsum to it, as sand will simply not split the lumps in it.

Mistake 2 – Bad Watering

The second, and common mistake, is what I would call “sloppy watering”. I am not just talking about overwatering and underwatering, as well as forgetting to quench your tomatoes’ thirst… I am talking about the way you do it!

Don't Make These 8 Tomato Planting Mistakes This Spring - You'll Regret #4! 1

Tomatoes are very susceptible to excess humidity, and drops of water on their leaves and stems. When you see black spots on the foliage, and sometimes on the stalks as well, it is often due to water splattering on them.

This can also encourage fungal infections and molds, so, first of all do not water your tomatoes from above, with a watering can, or with sprinklers! No – they are no good for them!

Water your tomatoes from below instead, and make sure you do not splash any on the base of the stem! So, if you do it manually, with a watering can, do it slowly. However, your best choice is a drip irrigation system. They are cheap and flexible, and you can use a timer to make sure they are watered regularly.

Mistake 3 – Not Hardening Your Seedlings Before Transplanting Them

This is such a common mistake that I will never stop repeating it: “Always harden your tomato seedlings before planting them!”

Not Hardening Your Seedlings Before Transplanting Them

Solanum lycopersicum or, as we call it, tomato, is a plant native to South America, and we often grow it in much colder climates. What is more, seedlings grow up in very stable conditions, whether you buy them or grow them yourself from seed. So, when you move them outside, they receive a shock, due to temperature changes, wind and strong sunlight.

What you need to do is get your tomato seedlings accustomed to harsher conditions.

Take them out for a couple of hours in the afternoon first; but not in full Sun and windy spots; find a sheltered position in part shade. Then, do it for four hours, 6 hours, 8 hours, 10 hours…
 Transplanting tomato seedlings starts about a week before you actually move them to their new home in your veggie garden…

Mistake 4 – Not Giving Support to Your Tomatoes EARLY!

As soon as your tomato plants reach 1 foot tall (30 cm) you must start giving them support, with stakes, a trellis, a cage, or, especially for indeterminate varieties, a Florida weave, by far the best way to “keep them straight. You can find all about it here.

Not Giving Support to Your Tomatoes EARLY!

If you don’t act soon, they will not grow straight, they may lean on the ground (and get diseases and rot), and in any case, you will find it more difficult to do it later… So, don’t waste time!

Mistake 5 – Forget to Remove Their Freeloading Cousins!

This is a very common mistake as well… Your tomato plants look florid, they are full of leaves, they grow big… But they have few fruits! And do you know why? You did not remove their suckers!

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Suckers grow in the armpits of the main stems, or branches… They are easy to find, and easy to snap off with your fingers, and wonder why they are called so? Because they suck the lymph (so energy and nutrients) off from the others that bear fruits.

But here we need to make a distinction:

  • With indeterminate tomatoes, you must remove all suckers, because they will bear little or no fruits.
  • Instead, with determinate tomato varieties, you should only remove the suckers below the first flowering stems; they will still bear fruits.

Next mistake…

Mistake 6 – Not Pruning off the Lowest Stems!

Once your seedling has grown into a small adult, and it does not need the lowest stems and foliage to produce flowers and fruits, prune them off! You don’t want your plants to be bushy at the base, you want them clean, and this is for many reasons:

 Not Pruning off the Lowest Stems!
  • Low foliage can get wet, and catch diseases.
  • Low foliage can make watering neatly hard.
  • Low foliage and stems will take off energy from the upper part of your plants, where it bears most fruits.
  • Low foliage can still bear some fruits, but then, because of their weight, they will touch the soil and rot away!

So, keep the base of your tomato plants clean, and there…

Mistake 7 – Not Mulching at the Base of Your Tomatoes

By all means, mulch your tomato plants as soon as you transplant the seedlings! Don’t wait…

Not Mulching at the Base of Your Tomato plant

Mulching them has many positive effects and no drawback:

  • It keeps the soil humid and fertile, saving you water and compost.
  • It keeps the lower leaves off the ground, so they don’t touch it and rot.

You can use any type of mulch for tomatoes, cheap straw or dry leaves are fine, but most tomato lovers use wood chips, which are a bit more “precious” and you wouldn’t use it for other vegetables, but given their soft fruits and issues with humidity…

Mistake 8 – You Planted Your Tomatoes in the Wrong Direction or Place!

Tomatoes need full sunlight, and lots of it! Otherwise, they will grow weaker, and their fruits will never get to that brilliant red (or purple, “black”, or golden, depending on the variety you choose) we all love them for. And not as sweet or nutritious either!

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So, grow them in a position where they get at least 6 hours of bright sunlight a day, and even more is better!

What is more, tomatoes can grow very tall, especially indeterminate varieties, so you need 3 to 4 feet between rows (90 to 120 cm) and 2 to 3 feet between them (60 to 90 cm). This, of course, depends on the variety, but make sure they have both sunlight and ventilation.

But then there is another coon mistake… What is the direction of your rows of tomatoes? Does it go east to west? Then, they will not get enough sunlight! They need to go north to south instead. This way, they will get both morning and afternoon Sun.

I know, intuitively, you may think, “But east to west exposes them to south, where the Sun is stronger!” True, but it only stays there for a short time, while in the mornings and afternoons it will light your tomato rows only from the sides, and the back half stays without it all day long!

…And a Final Tip…

So, here are the 8 sneaky mistakes you must avoid at all costs with your tomato seedlings and plants in spring. Now you know them and you also know how to avoid them, so you will get bountiful crops of healthy and ripe fruits later on.

But there is a final tip I would like to leave you with… Transplant your seedlings during the third phase of the Moon! This will help them develop strong and long roots, and it’s what you want with them at this stage. They will settle fast and grow healthy later on!

It is not a “myth” or “credence”; there are scientific reasons for it, and if you want to know all about it, check out our article on Moon planting here!

Amber Noyes

Written By

Amber Noyes

Amber Noyes was born and raised in a suburban California town, San Mateo. She holds a master’s degree in horticulture from the University of California as well as a BS in Biology from the University of San Francisco. With experience working on an organic farm, water conservation research, farmers’ markets, and plant nursery, she understands what makes plants thrive and how we can better understand the connection between microclimate and plant health. When she’s not on the land, Amber loves informing people of new ideas/things related to gardening, especially organic gardening, houseplants, and growing plants in a small space.

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