Tomatoes are one of the most popular crops to grow in home gardens. They are a useful and delicious crop and growing them can bring a range of rewards.
Often, they are relatively easy to grow, and can be abundantly productive. But there is also a lot that can go wrong along the way.
Here are 20 mistakes too many people make when growing tomatoes. By looking at this list, you should be able to avoid many of the common pitfalls and enjoy an abundant tomato harvest this year, or in the years to come:
1. Choosing The Wrong Varieties To Grow
First of all, it is very important that you make the right choices when deciding which tomatoes to grow.
You need to think about your climate, microclimate, soil and growing conditions when choosing the right tomato varieties. You also need to think about your own preferences and your own personal needs and wants.
Beyond this, you also need to think about the characteristics of the different tomato varieties you are considering. For example, you should think about:
- Whether the seeds are heirloom tomatoes (and will allow you to save seeds and grow more plants next year) or hybrid types (which will not come true from seed but may have better pest or disease resistance).
- The growing habit of the tomatoes (determinate or indeterminate), vining or bush varieties etc..
- The size and type of fruit, and what these tomatoes are best used for. For example, are they cherry tomatoes, plum tomatoes, beefsteak etc.? Are they best used for salads and eating raw, for cooking or canning? Or for making sauce? How will you want to use the tomatoes you choose.
- How long the tomatoes take to come to harvest. Fast-fruiting varieties are usually best for those with shorter growing seasons.
2. Not Providing the Right Conditions for Optimal Seed Germination
Whichever seeds you choose, it is important to create ideal conditions for seed germination. Tomatoes require a minimum temperature of 40 degrees F. for germination, but the best germination rates will be achieved when temperatures are between around 60 and 85 degrees.
Often, people do not get as many tomato plants as they could do because they are trying to sow them outdoors when it is too cool for optimal germination rates to be achieved.
This is why, especially in short seasons, it is best to sow indoors, under cover, before transplanting seedlings to their final growing positions once the weather has warmed.
3. Sowing Seeds Too Late
In cooler climates, once of the most common mistakes I have seen is sowing tomato seeds too late.
In a short growing season, growing tomatoes can feel like a race against time as we try to get a decent harvest before the cold weather arrives once more.
You need to sow tomatoes well before the last frost date where I live in order to get decent-sized plants to place out in the garden (in my polytunnel) once the weather warms.
I sow tomato seeds, along with other warm season crops like peppers in January or February indoors. This is one of the earliest sowing jobs of the year. I then plant the tomatoes into my polytunnel in late April or early May (depending on the weather) most years.
I encounter a number of people who do not sow tomatoes until spring. They often find that they get only green tomatoes by the end of the season. (Which isn’t such a bad thing, really!)
4. Not Giving Early-Sown Seedlings The Conditions They Need
When you have to start tomatoes indoors very early in the year, it is vitally important to make sure that you give them the conditions they need to survive and thrive.
The biggest mistake people make when it comes to growing tomato seedlings indoors early in the year is not thinking about light levels. Lack of natural sunlight is one of the biggest barriers to growing tomatoes indoors in areas which experience very short days in winter. Seedlings without enough light can get leggy, and weak.
It is important to choose as sunny a spot as possible in which to grow them. But plants may still need an extra helping hand.
LED grow lights can be useful, and using foil to reflect the light is another tip that might help. You should also turn seedlings around regularly to prevent them from leaning towards the light.
Of course, there are other conditions that need to be met. You’ll also need to choose the right growing medium, water well, and provide the right temperatures. But getting the light right is the thing that is often overlooked.
5. Not Potting Up Tomato Plants in Time
When you do grow tomato plants indoors, and whenever you do not direct sow them, it is important to think about when they must be moved to larger containers.
Leaving tomatoes, closely spaced in seed trays, or letting them outgrow their individual pots, can often cause a range of problems.
Tomatoes left too long in seed trays can face too much competition and become stunted. Tomatoes in small pots can become root bound, and can prematurely flower if they are left too long in their pots.
You need to pot up tomatoes to make sure their growth is not checked if you start them indoors long before the outside growing season begins.
Remember, tomatoes can be buried slightly lower in the top when potting up. New roots will form along the newly covered stem section and make for healthier, sturdier plants.
6. Forgetting To Harden Off Plants Grown Indoors
If you are sowing tomatoes indoors and growing them on to plant out later, another important thing to remember is that you need to harden off those plants before placing them outdoors.
Hardening off involves gradually acclimatizing plants to outdoors conditions. If you omit this stage, the shock of transplantation may stunt or even kill your tomato plants.
7. Planting Tomato Plants Out Too Early
Don’t be tempted to plant tomato plants out too early. Getting the timings right is crucial in gardening and this is particularly true when it comes to warm season plants like tomatoes.
I’ve known gardeners to rush to plant everything out when the first sunny, warm day in spring arrives. But it is important to be absolutely certain that the frosts have passed and warm weather lies ahead before you risk planting out your tomato plants.
8. Putting Tomato Plants in the Wrong Places
There are a range of different places where you could grow tomatoes. You could grow them, as I do, in a covered growing area (greenhouse or polytunnel). You could also grow them outdoors, either in containers, in raised beds or in the ground.
But while there are plenty of places which will be perfect for growing tomatoes, there are also plenty of places that are not ideal.
It is important to take the basics of climate, conditions, soil etc. into account. Think about sunlight and find an area of full sun. Make sure your tomatoes are not in a particularly exposed location or they may be damaged by strong winds.
It’s not rocket science, but you would be surprised by how many people get it wrong. I’ve seen tomatoes grown in a damp, cold and shady spot behind a garage, for example. Of course, the tomato yield was not a good one!
If you are growing in containers, make sure you choose containers that are large enough to accommodate your plants. Make sure, wherever you grow tomatoes, that their needs are met.
Don’t plant them too close to other plants, or to each other. And don’t put them far away from the things you will need when tending them. Water, compost/ fertilizer bins etc. should be as close by as possible.
And keep tomatoes close to your home so you can tend and harvest more easily.
9. Not Considering Support for Tomato Plants
Some tomato plants can support themselves. But many, indeed most, will require some form of support as they grow if you are to get the best from them.
Check out this article on supports for tomato plants to get some suggestions about which option to consider, and for tips on making your own from things that might be readily available to you where you live.
10. Forgetting To Think About Companion Plants
Segregating you tomatoes is not the way to go. By planting tomatoes alongside a range of other plants, you can take advantage of the beneficial interactions between them.
Diversity is key to creating a vibrant society, and the same thing is true in our gardens.
Companion plants or guilds around your tomato plants can help increase your yield and help you get the best possible results.
Borage, marigolds, basil and nasturtiums are common tomato companion plants, but you can see our entire list of veggies, herbs and flowers that benefit tomatoes here.
11. Watering Too Much, or Watering Wrongly
One of the easiest ways to go wrong in a garden is to give your plants too much water. It is important to understand how much water tomatoes require on average. But also how their water requirements differ over the course of their growth period.
Watering is most crucial during the flowering and fruiting stage. But adding too much water at the fruiting stage can cause fruits to split, or increase the risk of tomato disease. It is also a good idea to reduce and even stop watering as the end of the season approaches. This could increase the number of mature fruits you get.
Watering wrongly can also cause problems. It is best to water tomato plants at the base, and to avoid getting any water on the foliage and fruits. Water resting on foliage can increase the risk of diseases, and sometimes cause scorching in hot sun.
12. Watering Too Little
Of course, watering too little is also a common problem. It is important to make sure that you don’t forget to water. Not having enough water will stress and can even kill your plants.
Try to set up a reliable watering system, so your tomatoes are taken care of throughout the summer, especially when things are dry.
This is where a rainwater harvesting system can really be crucial to making sure you have water to get you through dry times.
13. Not Fertilizing Tomato Plants
You’d be surprised by how many people just stick tomato plants in the ground or in containers, and expect the soil and sunshine to deliver what they need.
But not fertilizing tomato plants can significantly reduce yield. Tomatoes are relatively ‘hungry’ plants, and they do need some extra feed, especially during the flowering and fruiting period to achieve the best harvests possible.
I use a comfrey liquid feed on the tomatoes in my polytunnel, in addition to adding slow-release fertilizers in the form of mulch (see below).
Related Reading: My Homemade Tomato Fertilizer Recipe Perfected Over 30+ Years
14. Or Using the Wrong Tomato Fertilizers
But when using fertilizers on your tomatoes, it is important to realise that not all fertilizers are perfect for tomato plants.
Tomato plants do need plenty of nitrogen, especially during the early stages of their growth. But adding a general purpose, nitrogen rich fertilizer to tomato plants when they are flowering and fruiting can actually do more harm than good.
Adding too much nitrogen can encourage plants to put too much energy into putting on green, leafy growth. And this can limit the yield by drawing the plant’s energy and attention away from flowers and fruit.
Of course, it is also very important to choose only good quality, natural, organic fertilizers. Not gardening organically is perhaps the biggest mistake you can make in your garden.
Short term, things may look great. But longer term, you’ll be damaging the garden ecosystem in a range of different ways.
15. Not Mulching, or Choosing the Wrong Mulch for Tomato Plants
Adding a mulch around tomato plants is crucial for maximising yield and getting the best results possible. Mulches act as slow-release fertilizers, build and improve the soil over time, help retain soil moisture and protect the soil surface.
But it is very important to choose the right mulches for your tomato plants.
The nitrogen issue described above is also relevant when it comes to the mulch that you use around tomato plants. Avoid nitrogen dominated mulches like grass clippings and opt instead for a mulch of comfrey, good quality compost or another more balanced mix.
16. Not Dealing With Tomato Pests in a Timely Fashion
In an organic garden, the best way to deal with pests is wholistically. By creating biodiverse ecosystems, with plenty of plants and beneficial wildlife, we can keep things in balance.
This reduces the incidence of pest problems. But there are still certain to be times when you encounter tomato pests.
Take a look at our article documenting twenty of the most common tomato plant pests and how to deal with them.
17. Not Staying on Top of Tomato Diseases
Prevention is always better than cure. But tomato plants can often also suffer from a range of diseases.
How severe a problem a disease will be will depend, of course, on what type of disease you are facing. But it will also depend on how healthy and vigorous your plants were to begin with.
Keep tomatoes as healthy as possible, and maintain good hygiene and environmental conditions, and disease is less likely to take hold.
But when disease does strike, it is very important to stay on top of things. Often, all you can do is remove affected foliage or fruits as soon as possible.
Many gardeners let things slide. But by remaining vigilant and acting at the first hint of a problem, it is often possible to prevent its spread.
18. Not Pruning Tomato Plants For Optimal Harvests
Pruning tomatoes is a good idea for those who want to make the most of their garden space and get the best possible yield.
Here’s our step-by-step guide to pruning tomatoes with photos.
And once you’ve pruned your plant – avoid waste – don’t throw those plant sections away! You could use them to clone new tomato plants from cuttings.
19. Not Taking Measures to Ripen Green Tomatoes Late in the Season
Pruning also plays a role later in the season. As the first frost rapidly approaches, there are a number of things that you can do to make sure green tomatoes ripen as quickly as possible.
Take a look at our article to find out more about how to get green tomatoes to ripen.
By taking the measures described in that article, you can make sure you get as many ripe tomatoes as possible before time runs out this year.
20. Letting Tomatoes Go To Waste
But remember, you can use those green tomatoes too. In this article you’ll find some tips on what to do to make the most of them, and to avoid any of them going to waste.
And throughout the whole of the harvesting season, one common mistake I see is gardeners letting their tomatoes go to waste.
When you have a glut of a particular fruit or vegetable, it is easy to feel overwhelmed, and wonder what to do with them all. Fortunately, there are plenty of ways to use up your tomatoes – no matter how many you have.
And you can preserve your tomatoes with canning methods, by drying them, or by turning them into interesting preserves to last you through the rest of the year.