Tomato Top Questions

I grew up on a small subsistence farm in Connecticut. I am not sure how young I was helping my father plant and weed our vegetable garden, but when I joined the 4-H Clubs of America at age ten I thought my goal in life was to teach my father the correct way to grow veggies and, especially, tomatoes. Most farmers and folks did not stake tomatoes then as we do today. The spacing was about 4-5 feet and they sprawled on the ground. My father was one of the first in his family to stake and space the plants about 2-feet. I tried to educate my father that, according to the 4-H, the plants should be at least 3-feet apart. My father thought the extra space was wasted and kept the 2-foot spacing in spite of my efforts to educate him. I couldn’t teach him much. I grow and stake my tomatoes 2-feet apart. Amazing how much my father learned by the time I had my own garden.

My father taught me how to grow and sucker the plants. We did not grow hybrid varieties but an Italian paste variety that I now grow and call ‘Cipolla’s Pride’. It will be offered for sale in Johnny’s Selected Seed catalog, 2021. The plants grew tall and my job was to sucker and harvest the fruit. The two nightmares I have about this simple task was to reach into the plant and touch the very large Tomato Hornworm or the orb web of the yellow and black Argiope spider or the spider itself. As I recall, they were as large as my hand. Maybe larger. The Hornworm is about 4-inches long and has a horn on its back end. I was convinced it would stab me and that the spider would bite and poison me. But I was not scared. I just somehow forgot to prune those plants if those two life-threatening critters were near.

Tomatoes are one of the most popular crops to grow in the backyard. They are not always easy to grow. They tend to have more air- and soil borne-diseases and pest infestations than other varieties. Those diseases fall into one of three categories: fungal (molds, mildew), viral (mosaic or mottled foliage, stunted growth) or bacterial wilt or fruit with black spots surrounded by circular rings-haloes. They can also be prone to physiological issues, such as Blossom End Rot or blossom drop or cat-facing.

What to Grow?

If your yard has less than 6 hours of sunlight, choose the smaller, cherry-sized tomatoes with shorter maturing times. If growing tomatoes are new to you, start with hybrids, determinants, the more resistant varieties and those that mature quickly. If your yard has less than 4-hours of sunlight you may be able to grow the plant, but may not see much to harvest. If your yard is mostly shade, forget growing tomatoes.

What does hardening mean?

You need to condition your plants to the outdoors by exposing them gradually to the sun and wind. If you purchased store-bought plants, they were probably outside the garden center. How long have they been outside? You don’t know. To make sure that your plants have been hardened, put them outside in the shade, for a couple of hours for the first few days, gradually increasing their exposure over the next week or so to the sun and wind or breeze if you live in the city. The process is the same if you started your plants from seeds, just extend the time to at least 10- to 14 days.

When to plant?

Tomatoes are warm-weather varieties. They thrive in warmer soil. In Zone 4, that usually means you may need to wait until mid to late May and for Zone 3, late May to perhaps even the first week or so of June. I tend to rush the season a bit and often put my plants out on or about the first or second week of May and protect them with floating row covers or low-tunnels if the forecast is for cool (cold?) nights (below 45-degrees). Depending on the weight of your row cover, you could increase temperature under the cover by at least 5- to 8-degrees. With low tunnels the increase could be as much as 15-degrees (or more).

How to plant?

Go deep. Bury your plant up to the first layer of leaves. Tomatoes will form a root system along the buried stem. This can produce a stronger plant with higher yields. If you live in or are expecting a dry summer or your seedlings are spindly, plant them horizontally (trench planting). That is, plant them as an “L”, being careful not to snap or break the stem of course.

When and Why Mulch?

Mulch will help suppress weeds and keep the soil cool but cool soil will inhibit growth. Only mulch after the soil has warmed and the plant is growing well. Mulch will help your plants maintain a more consistent soil temperature and moisture level, especially during the hot summer months. Mulch can provide resistance to some soil-borne diseases, such as Septoria Leaf Spot and some physiological issues, such as Blossom End Rot.

What is the best variety?

There is no such thing as best until you define what you mean by best. Are you looking to grow one that has a nice yellow color? A deep red color? One that has higher levels of lycopene (anti-cancer properties)? What about a colorful striped green-yellow pattern? Or those that are deep purple, almost black? A pinky one? Do you prefer a sweet variety? Is plant size one of your preferred characteristics, one that only grows to 18 inches? Do you plan to grow them in containers? Is fruit size important, say one that will cover a slice of bread? Do you want to have tomatoes earlier than your neighbor so you can brag? Do you want a variety that is tolerant to cooler temperatures? One that makes a great sauce or is good for canning? Do you prefer a smooth-skinned variety or one that has deep ribs? Or, do you want a nice juicy variety that squirts seeds and juice from your mouth when you bite into it? When you define what you are looking for, grow it and if you like what you are looking for—taste, size, color, and so on—then you may have found a best variety that satisfies you. Tomato descriptions are much more informative in a seed catalog than what you often find on a seed packet. One caution: Seed catalogs often describe a variety as new. They are not (usually) a new variety, but a new addition to that company’s catalog.

Hybrids or Heirlooms, what is the difference?

Hybrid tomatoes are cross-bred from two or more different tomato plant varieties. They are created for a specific purpose, based on what consumers (you) and commercial growers (them) want: disease resistance, color, shape, yield, shipping qualities, etc. Hybrid seeds will revert to one of the parents and you do not know which parent until you plant that seed the following year. As a result, saving those seeds will not be reliable. That is, they will not produce the fruit that you thought was great this year and that is why you saved the seeds. Of course, if you don’t intend to start plants from seeds, then this is a moot point. The trend towards newer hybrid varieties is towards higher sugar or Brix levels because more consumers (you) prefer sweeter food. Breeders breed what consumers want to eat. Hybrid skins tend to be thicker, allowing them to ship across the country without spoiling or marking the skin. Consumers (you) tend not to buy fruit that appears spoiled or funny-looking. Hybrid fruit tends to have a more consistent-shape, size, color, etc.-- than heirloom fruit. Heirlooms are open-pollinated by the wind, bees (bumblebees). They are handed down from generation to generation and are at least 50 years old. Folks passed them down because of certain qualities they valued--taste, color, shape, yield, etc. Their seeds can be saved from year to year. Heirlooms tend to have thinner skin. They can bruise easily. They are prone to a nasty range of diseases. Heirloom varieties almost always lack the deep red color and sugar processing ability and may not be as sweet as some hybrid varieties. If you choose to save the seed, for your own consumption/backyard, they should be at least 25 feet from any other tomato variety. If you hope to have them as a commercial variety, isolation should be at least 50 feet.

How do I know if I bought a hybrid or heirloom variety?

Hybrids list letters (sometimes with numbers) after the varietal name. Open-pollinated or heirlooms do not (generally). The best hybrids have several letters after the varietal name, e.g., VFFNTA, which means that variety is resistance to six diseases.

Which is better, hybrids or heirlooms?

And just to be clear: hybrids are not Franken-food. They are not engineered through transgenic technology. They will not cause you to break-out in pimples. In general, hybrids offer multiple characteristics that consumers are looking for: dependability or consistency of the fruit, easy maintenance, early maturity, better (higher?) yields, improved flavor, plant size and almost all offer a level of disease resistance. Resistance is the key word. It does not mean elimination of disease. By contrast, heirlooms usually have a better balance between a sweet and acidic taste. Often heirlooms are described as having an old-fashion taste, aka a balanced-taste-flavor. They can be better for canning (higher acidic levels) without you having to add lemon juice to ward off botulism. Caution: telling folks that you are growing hybrids could conjure up images of devil-worship from some folks or accusations of you being a free-thinker. On the other hand, saying that you are growing heirlooms could conjure up images of you being a traditionalist or arch-conservative. Be careful out there. Prejudices run deep. Plant both. Plant what you want. Plant what you like.

What is the difference between an Indeterminate and Determinate variety?

Most hybrids are bush or determinate (or patio or container-type) varieties that grow to about 3-4 feet. They stop growing when fruits form on the top buds. Most of the fruit matures-ripens at about the same time, say over a 4- to 6-week period and usually they do not need supports. Indeterminate varieties can grow from 6- to 12-feet and require support (unless you choose to let them grow-sprawl on the ground, which is how most tomatoes were grown prior to the 1960s, for those of you who were around then). Heirlooms tend to be indeterminate. They continue to produce throughout the season until the fall when frost stops them. Do you want your tomatoes to ripen within a set time period? Hybrids would be good. If you want tomatoes from, say June/July to October, heirlooms would be good.

How to control tomato diseases?

The UMN Extension website is a great place to start. You can have some control over some diseases, but not others. You can control (not eliminate) Septoria Leaf Spot (SLS) and reduce insect damage, such as cutworms, by practicing botanical rotation (not growing any member of the Solanaceae family (tomatoes, peppers, eggplants, Irish potatoes, for at least three years) and mulching after the soil has warmed. You can also strip/cut the lower lateral branches so you have a stalk without leaves of about 12-inches. When heavy rain splashes on the soil, it releases the SLS spores. Mulching helps. Cutting those lower branches helps. Controlling air-borne diseases, e.g., Early and Late Blight, is a bit difficult and close to impossible. Yes, you could try fungicides if you apply it before you see the disease. Yes, you can create wider spacing between plants. Yes, you can limit overhead watering. No, you cannot control the weather- wet, cool, humid conditions, spores carried onto your plants by the wind. And just to clarify: rain is overhead watering.

Why do my tomatoes turn black on one end?

Welcome to Blossom End Rot (BER). This is a common physiological disease. It is not a fungus or virus or bacterial issue. It can occur because you used too much fertilizer (high in Nitrogen), or your soil has a high salt content or that watering is intermittent or uneven or because of a calcium deficiency. It can occur on green and ripe fruit. It never occurs by the stem or on the leaves, but only at the end or top of the fruit, ergo the name end rot. BER affects all varieties in the Solanaceae botanical family—peppers, eggplants as well as other plants, such as cucumbers. Calcium deficiency is almost always identified as the main source. As you just read, there could be and usually are multiple sources that cause BER. Calcium (Ca) has a critical role in the growth and nutrition of the plant, including the cell walls. Ca can help maintain the chemical balance in the soil, reduce salts in the soil and improve water penetration. If Ca is deficient, you will see distorted growth on shoot tips and young leaves. If Ca is deficient, roots will become stunted and discolored (which you will notice if you happen to dig up the plant). Your plants will be more susceptible to root diseases. Ca needs water to be transported through the plant; keep soil moist, not wringing wet. Therefore, maintain a consistent watering schedule to allow the proper transportation of calcium through the plant system. Your soil may not need calcium. The UMN does not test for that, but it does provide results for salt in your garden soil. You can add calcium using egg-shells or oyster shells. Lime can help raise your pH (which is generally not necessary West of the Mississippi River). Gypsum will help maintain your current pH level. You can also add bone meal. BER is a physiological problem, therefore fungicides will not work. Save your money. After the soil warms, mulch with peat or coir or straw or compost or grass clippings to conserve moisture.

Physiological problems

(a) Why are the leaves turning yellow. This could be just the normal aging-maturing of the plant. As you get older, you have hair loss, you get wrinkles, body parts start to sag. Plant leaves yellow, turn brown, sag and drop. It could also be a lack of nitrogen in the soil. Add some and see what happens. It could be a fungal or bacterial disease, such as Alternaria alternata, which would require you to (a) ignore it or (b) buy a fungicide and nuke it.

(b) Why are my tomatoes cracking and splitting. Some varieties are prone to split. They could be splitting because of fluctuations in the temperature—spikes in high and low temperatures—or water fluctuations—you soak them, then fail to water them until they start to wilt and look weak.

(c) Why is my plant nice and bushy but there are few tomatoes? One reason could be a lack of pollination. However, most varieties are self-pollinating. Usually, it is because there is a period of cool (cold?) weather, windy conditions and/or wet conditions (re: summer of 2019). Tomatoes need moisture, but they are not comfy if their roots are in water (hydroponic-gardening an exception). Raised beds. Containers. Both can help keep the root system moist, but not sitting in water. Another reason could be that you used too much fertilizer, high in nitrogen. Nice bush, no fruit. If you think the problem is a lack of bumblebees, you could hand pollinate them or just give them a smack upside the stem and leaves as you walk through your garden. Bumblebees vibrate their wings next to or on the flowers to loosen the pollen. A nice, well-placed smack has the same effect.

(d) Why do the flowers keep dropping on my plant? Temperature influences when and if the fruit develops. Blossom end drop occurs when the temperature is cool, say below 50F or over 85F for an extended time period. If the temperature remains high, the blossoms will drop and, therefore, not produce fruit. Dropping blossoms is one way the plant survives. Smaller varieties (cherry-type) mature faster than larger varieties and could avoid the extreme heat of summer. Hybrids tend to mature quicker than heirloom varieties.

Can I grow tomatoes indoors?

Absolutely. You can grow them hydroponically. You will need an artificial light source—LED, Fluorescent. Tomatoes are self-pollinating. Bumblebees are not required. Though if you are in doubt, as I mentioned above, you could ensure that the pollen loosens by giving them a smack upside the stem-leaves when you walk by. Setting up a floor fan at low speed for an hour or so a couple of times per week will also help.

What is a sucker and why do it?

Hybrids and patio-type tomatoes generally do not need to be pruned. Heirlooms almost always need pruning or suckering. The sucker, or part to be pruned and removed, always occurs at roughly a 45-degree angle from the main stem and a lateral branch. There are two schools of thought about removing the suckers. (1) When you prune, you should get fewer fruit, but they will be larger because the plant’s energy will be focused on developing the fruit not additional leaf-growth. If you prune excessively, you could create a physiological problem: sun-scald on the fruit. (2) If you do not prune, you will get a higher yield, but the fruit will tend to be smaller. If you let the plant grow as much as it wants, you will get a great looking bush.

What to do with the suckers?

Toss them. If they are not diseased, compost them. Or, you can place the sucker in a glass of water and allow it to root. You can then take that sucker and plant it in a container or your garden in soil or water (hydroponics). You can also do this with peppers, by the way. The main down-side is time to maturity. If you do not sucker until, say late spring or early summer, your variety may not produce fruit before a hard, killing frost. If your hybrid variety happens to produce suckers you could cull them, root them and plant them. Any fruit will produce true for the current year.

Maintaining your Plants.

Organic gardeners: If you use compost, you will need to use a high Nitrogen fertilizer-amendment to breakdown the organic matter so your plants can absorb its nutrients. No plant can intake solid matter. It needs to be broken down into a soluble consistency. That is the function of earthworms, soil bacteria, creeping crawlers, etc. One option is to use blood meal. If you do not add extra Nitrogen, your plants will grow slowly and the leaves could turn yellow.

Other gardeners: if you use a commercial fertilizer apply it about a week or two before planting your tomatoes to allow it to start working in the soil and breaking down any solid matter. If you choose to add a second application, do so on or about July 4^th and use a mix that is lower in Nitrogen (N) and higher in Phosphorous (P), which benefits any fruit-flowering plant. Phosphorous is illegal to use on your lawn because it can leach out into waterways—rivers, lakes, oceans, etc. If leaching is not possible in your yard, then consider using it. Most fertilizers for gardens include phosphorous. Bone meal is an excellent source and you can use it whether you want to be called an organic-gardener or not. I do not fertilize my plants after July 4^th. I want them to produce fruit, not leaves.

Myth Buster

Basil will not improve the flavor of tomatoes when grown next to each other. No plant can impart its flavor characteristics or other traits to another plant. Companion planting works best when you plant a tall plant next to a shorter plant, or when you plant a short maturing plant next to a longer maturing plant. I believe that the fragrances of different plants co-mingle and confuse the bad insects from finding your favorite plants. This may be anecdotal. This may not be a scientific fact. I do that because I like doing it and it does not cause harm to any of the plants that are growing next to it. And, it is one great way to fill in the space between tomato plants. I am pretty sure I taught my father that.