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Nothing says summer more than fresh tomatoes! Store-bought tomatoes just can’t be compared. There are some common avoidable mistakes made growing tomatoes.
Though tomatoes are one of the most popular fruits to grow, some people find it very easy to grow them in their garden, while others struggle.
Today we’ll talk about 11 common mistakes made growing tomatoes and how they can be avoided.
I mean, let’s face it. Who wants to work hard for months growing tomatoes from seeds, only to transplant them into the backyard garden and have them die within just a few days? Not me, and I don’t want you to either.
It doesn’t matter if you are growing only a single tomato plant in a container on the deck or if you have acres of them. If you don’t avoid these common mistakes, the result could be disappointing.
RELATED: Even if you’ve never gardened before, this Vegetable Gardening for Beginners Ultimate Guide is for you! Learn everything you need to know from over 60 resources, all in one place, to be a successful gardener, including improving soil, cover crops, warm and cool season crops, organic amendments, fertilizing, watering, and so much more.
11 Common Mistakes Made Growing Tomatoes
Planting too Early
Tomato seedlings are heat-loving plants and don’t like cool temperatures at all. Once the soil is properly prepared and soil temperatures are correct, tomatoes can be transplanted into the garden. Young plants should be about 6-8 inches tall and properly hardened off before transplanting.
Planting the Wrong Variety
Determinate vs. Indeterminate
Gardeners must make 2 important decisions. The first is the determinate or indeterminate habit of the plant itself.
Determinate tomatoes top themselves off in growth at around 3 feet high. They will stop growing in height and begin to set flowers for fruit. Determinate tomatoes can be easily well-managed in a home garden.
Indeterminate tomatoes continue to grow and produce both new leaves and new flowers. The indeterminate will continue to grow all summer into fall, producing fruit, unless damaged by disease or insects. These make a great tomato for being able to have fresh tomatoes the whole summer and into fall.
The second important decision is in deciding on the specific cultivar. There are hundreds of varieties available. It’s important to choose either heirloom for purity or a hybrid that is disease resistant. To better understand heirlooms, hybrids, GMOs, etc., take a look here.
A great source for information on various cultivars is the All-America Selections site. They provide cultivars that have been tested at sites across the country and found to be good performers in the backyard garden.
Improper Spacing
Spacing depends on the type of tomato. If plants are spaced too closely, airflow is restricted, and they can shade each other out, resulting in little production of fruit.
Determinate Tomatoes should be spaced a minimum of 18-24 inches apart, with each row approximately 48 inches apart. Indeterminate tomatoes should be placed 23-36 inches apart with row spacing 60-72 inches apart.
I grow determinate varieties in my raised beds. Since the majority of the beds are only 2 feet wide and 30 feet long, I place the plants 2 feet apart the length of the beds. I get 15 plants in each bed.
Over Fertilizing
Tomato plants should be fertilized with a “complete” fertilizer. The NPK, micronutrients, needs to be pretty much level at the initial planting and again when the plants begin to produce fruit or blooms.
A good NPK is adding a cup of diluted chicken manure in 4 gallons of water and mixing thoroughly. Then add crushed eggshells around the base of the stem on the soil.
Be careful not to add too much nitrogen, as it may promote the growth of the leaves but reduce fruit yields.
Regular fertilizing should be done every two weeks once the plant begins to produce fruit actively. The timing of this application is after the first cluster of fruit has set, and tomatoes are about the size of a large marble but smaller than a golf ball.
Improper Watering
All plants benefit from consistent soil moisture. They need to be able to partially dry or slightly dry out between watering. This will help to force the roots to grow deeper, making the plant stronger.
The soil should be kept wet enough to prevent wilting of the tomatoes. Garden tomatoes generally require 1-2 inches of water per week. This can change, though, depending on environmental conditions, such as excessive drought, as well as the size of the plant.
Watering Too Often
This can cause issues in plant growth as well. Frequent shallow watering will cause plant disease. Drip irrigation is best for watering tomatoes and avoiding strong streams of water that erode the soil.
As the tomato plant matures, water more slowly and deeper. Tomato roots can grow 2-3 feet deep in good loose soil, therefore needing to be watered around 18 inches deep. Deep watering is important in the summer heat.
Watering from Above
Watering from above can be detrimental to the entire tomato crop. Disease and bacteria can thrive in both warm and wet conditions as well as cool and dry conditions. It is best to put the water directly onto the soil to keep it off the leaves.
Watering at the Wrong Time
The best time to water is when the sun is low, and the temperatures have decreased a bit. It really depends on your schedule. If you are able to water early in the morning before the sun comes up, great, but if not, watering in the evening will work; it just needs to be cooled down.
I realize that mornings are super busy with getting ready for work, getting kids ready for school, and whatever else you must do each morning.
Just be sure to water when the sun is not high in the sky, and the temperature is not so hot the soil is unable to absorb the water before it evaporates.
Related: Learn more tips and tricks about How and When to Water a Garden
Lack of Pruning
Prune indeterminate varieties only. Pruning determinate tomatoes can reduce harvest, so allow them to grow.
Reasons for pruning indeterminate varieties can be very beneficial. It can improve airflow to help in preventing disease. Since air and sunshine are able to flow easier through the plant, the fruit tends to ripen more quickly. Pruning also increases yield per plant, as well as helps with producing larger fruit. I like these shears for pruning tomatoes.
Pinch indeterminate varieties back when about 8 inches tall. This will help to encourage lateral growth of the plant or spreading of the plant.
Not Mulching
Tomatoes enjoy the heat, but keeping the soil around them moist and cool is necessary. Soil left uncovered can cause the plants to dry out as well as cause diseases too.
Layer mulch 2 – 4 inches deep around the plant. Pull back about 2 inches from the stem itself. Form a small “moat” with the mulch. This will allow for water to get deep into the roots.
Mulching is beneficial in several ways for tomatoes. As I have already said, it helps to hold in moisture. It also helps to control weeds and helps to prevent the spread of disease.
Improper Support
Support tomatoes within just a few days of being transplanted while still small. If the plants are small, it will help to prevent damage to the plant and its roots when driving the support into the ground. Both determinate and indeterminate varieties need support in order to keep them controlled.
Three popular ways of supporting tomatoes are staking, caging, and trellising. The support does need to be strong enough to hold the plant and the fruit off the ground.
Staking
Staking requires wood or metal stakes that are 5-6 feet long for indeterminate varieties and stakes that are 3-4 feet long for determinate varieties. Do not use chemically treated wood. Tie the main stem of the plant loosely but securely to the stake and continue to tie it as it grows taller.
Caging
Caging requires less work than staking because there is no tying involved. These cages work great, or you can also use concrete wire, hog wire, etc. The opening in the wire needs to have an opening of 6 inches to easily give you room to reach inside to remove the fruit.
Determinate cages need to be about 3 feet tall and 18 inches in diameter. Indeterminate cages should be 5 feet tall and 24 inches in diameter.
As the plant grows, prune indeterminate varieties as needed. Push determinate variety leaves back into the cage; no need to prune.
Caged varieties may not ripen as quickly as staked or trellised varieties, but they will more than likely have less sun-scald and cracked.
Trellising
Trellising tomatoes is a third option as well. Indeterminate varieties work really well on a trellis. The easiest way of trellising tomatoes is to use metal posts and a trellis net, string, or wire tied from one to the other in rows.
The string or wire does need to be strong enough to hold the heavy limbs of fruit up securely.
We’ve talked about several mistakes commonly made when growing tomatoes. You may now realize that you are doing a couple of these. If so, don’t fret; now that you know, it is the perfect time to correct the problem.
Remember, proper care of tomatoes will increase yields.
Did you find that you have made one or more of these mistakes that are preventing you from growing large yields of tomatoes? Feel free to leave comments below.
Great Ways to Preserve Tomatoes
- Canning Whole Tomatoes
- Canning Tomato Juice in a Water Bath
- Easy Sun-Dried Tomatoes
- Homemade Spaghetti Sauce Canning Recipe
- How to Make and Can Pizza Sauce
- How to Freeze Tomatoes for Easy Peeling
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Dianne Hadorn is the owner of Hidden Springs Homestead nestled in the hills of East Tennessee. She is a Master Gardener and enjoys helping others learn how to grow and preserve their own food and sharing tips for living a more sustainable life.
How do you know if a tomato plant/seed is determinate or indeterminate?
Hi Toni,
Great question. If you have the seed packet, it will normally tell you. But, to tell the difference once they are planted – If the plant gets more than 3-4 feet tall, it is not determinate. The branches will become leggy and grow longer, constantly needing to be staked. This is indeterminate. Another way to tell is to look at the branches. If they are close together, it is most likely a determinate because indeterminates stems are more widespread for branching out. If you cannot tell with these suggestions, feel free to send me the variety name, and I will do my best to help you.
Thanks for reading,
Dianne
Hi, I am growing San Marzano tomatoes…they are doing great but I’ve noticed as they ripen they have a hole in them (size of a dime or larger) The leaves are fine, I haven’t found any caterpillars on them.
I have brought the tomatoes inside and cut them open but I don’t see any worms etc.
Would you have any thoughts as to what is happening?
Thank you.
Hi there,
That is a really big hole. Tomato Fruit-Worms do make holes in tomatoes, but they are about the size of an eraser and then the tomato will turn black inside from the worm being in it eating on the meat of the tomato.
Without seeing a picture, I really hate to guess, but with the size it sounds more like a lizard or some type of mole or even birds eating on them. I’d recommend going out EARLY MORNING before the due dries off and look them over carefully and then again just before dusk. I’ve had a couple lizards this year in my garden that did eat on some things, but the cats took care of them pretty quick. Of course, lizards eat slugs too – so it is a good cycle. NOTE: If its a mole, you’ll probably never see it.
I tend to pull my tomatoes off the vine when they are only about 1/2 ripe and bring them inside to continue to ripen. The red is what attracts critters and I lose less tomatoes this way. Just lay them on a table, single layer, and give them a few days. They will ripen without blemish.
Let me know if you find the culprit. I’m interested.
Great information provided in a very concise manner. I have been raising tomatoes for many years and did not know what I did not know. I learned so much, particularly about watering practices and the pros and cons of a trellis vs. a cage.
FInally, the reference materials are wonderful as I am able to easily access specific details. Thank You so very much. Cheers…
BlueWaterSailor
High Springs, FL
Very good information.
The main problem I have with all my vegetables is they never grow to maturity. I get lots of them but don’t know what I’m doing wrong.
Thanks in advance for any help. Also I live in AZ.
Hi Brown Thumb,
Obviously our growing zones are much different, but no matter where plants are being grown, they all require the same thing – water, soil and sunlight.
I’m thinking out loud, but some things to look at are – the amount of sun – is it too sunny – are they baking? If so, look into shading them with larger plants or even man-made shade such as sunscreens.
And then their water – I know your rainfall is less than ours, but the plants still require the same amount. My raised beds require more water since they drain so well. Could you water more to keep the roots nice and healthy. Here is a link on watering the garden.
Maybe an irrigation system would help. I installed a system from Drip Depot (affiliate link) – irrigation is the only thing they do, so they specialize. AND – also about water – plants don’t do as well in chlorinated water. If you are using “city water” it could be harming your garden. Let it sit for 24 hours, chlorine will evaporate, and then feed it to your plants.
And then soil – soil is vital to plant thriving. Maybe this post about healthy soil help.
This is a lot to comment, but I am totally committed to helping people succeed in growing food. I am willing to help all I can. You can reach out via this comment area, email me at dianne@hshomestead.com or you can reach out via the Hidden Springs Homestead FB page. Make a post to ask questions or message me – either way. I’m here to help figure it out. (not proofread)
Lets change that brown thumb to a green thumb.
Happy Gardening,
Dianne
Great post! Although, my success with tomato growing has been a bit varied, but even if I only get a few fruit rather than loads of them, just to pick and eat them straight off the plant when they are juicy are so much better than shop bought ones.
I observed 3 dying green bettles in my backyard a couple days after spraying my fruit trees (soursop & mangoes) to gwt rid of a fungus. I wondered if they were pests or beneficial to the trees. Can you advise?
Hi Lyn,
Thanks for visiting my site. I would love to answer your question but from the fruit trees you are growing, it sounds like you may be in the tropics. I am in Tennessee and have no knowledge about tropical insects or plants at all.
I can steer you in a direction to hopefully help you get an answer though. You need to do a couple things:
First, search to find out what kind of beetle you observed – here in the US, my go to for researching insects is the National Audubon Society. There is website is: https://www.audubon.org/ They have an excellent website you can take a look at. They also have a great book for identifying insects “National Audubon Society Field Guide to Insects and Spiders.” Here’s my Amazon affiliate link for it: https://amzn.to/2NDF031 I have this book and use it often in the garden.
Another good site is called The Insect Identification site, their website is: https://www.insectidentification.org/. It’s simple to use and full of information. From these two, maybe you can identify your beetle from there.
Next, once you identify the beetle, I would of course “google” the species to find out information about it and figure out if it was beneficial or not.
It’s a difficult decision when our plants have a fungus or disease and we have to make that decision to treat or not to treat.
Unfortunately, sometimes treating the fungus causes harm to the ecosystem.
I’m sorry that I’m unable to give your more but I think this is a great starting place for your research. Good luck with it and let me know how it turns out.
Thank you so much for mentioning the All-America Selections! Our goal is to give gardeners the right best varieties for success in their gardens. We test new varieties across North America and only the best become AAS Winners – “The Proof is in the Plant”
You are so welcome.
Melissa, I used to have a problem with blossom end rot with tomatoes and pepper plants. I learned that it is due to calcium deficiency and sets in when the flowers are pollinated and the fruit first sets. It can be due to low calcium in the soil or from low moisture in the soil at the time of fruit set not allowing the plant to absorb calcium. I started saving my egg shells through the winter and grinding them into powder in the blender. I mix the egg powder in at planting time (or shortly there after) and pay closer attention to soil moisture. Have not had blossom end rot on any fruit since…
Leah, you are correct – blossom end rot can be due to a lack of calcium in the soil. Getting a soil test would be very helpful for you Melissa. Here are a couple of links to 2 of my other posts that you could take a look at for creating healthy soil and a 3rd one to help when you plant initially plant your tomatoes. Hope they are helpful. Please feel free to ask more questions.
https://www.hiddenspringshomestead.com/how-to-give-garden-calcium-boost/
https://www.hiddenspringshomestead.com/how-to-give-garden-calcium-boost/
https://www.hiddenspringshomestead.com/how-to-grow-healthy-tomatoes/
Interesting! We almost always have a tomato plant or two, but had some issues with blossom end rot. I haven’t done several of these tips so I’ll be putting them into practice!
Melissa,
So glad it helped. Let me know if you have questions. I’d be glad to help.
Melissa, take a look at a reply to Leah. I’ve put in a couple links to hopefully help you with blossom end rot.