All about tomatoes

Your Tomato Questions Answered

I love tomatoes. They are one of the most popular plants among gardeners. They come in an array of colors, shapes and sizes and can be relatively easy to grow. Read on to learn all about tomatoes including fun facts, health benefits, how to grow tomatoes, how to identify and treat diseases and pests.

Is it a fruit or a vegetable?

I love fun facts! This is a good one for kids. Are tomatoes a fruit or a vegetable? They’re both!

Botanically speaking, tomatoes are a fruit because they contain seeds. Fruits are classified as a growth on a flowering plant that’s sole job is to spread the plant’s seed. A vegetable is simply an edible part of a plant. So how is it also a vegetable? Nutritionists, and the tax man, label tomatoes as vegetables because of how people generally eat them. They are eaten as part of a main meal and not as a snack or dessert. Call it a fruit or a veggie or whatever will get your kids to eat it, just make sure it’s growing in your garden this season.

Are tomatoes good for you?

Tomatoes are packed with vitamin C, vitamin A, potassium, calcium, and the antioxidant lycopene that is good for your heart. Surprisingly (or at least to me), tomatoes are better for you cooked than raw, as the cooking process breaks down the cell walls, making it easier to digest. There are over 7,500 varieties of tomatoes, so branch out and try a few different ones. They come in an array of colors, not just red. Tomatoes can actually be red, green, yellow, orange, pink, black, brown, white, and purple.

What are determinate and indeterminate tomatoes?

There are two main types of tomatoes, determinate and indeterminate. Knowing which to choose and recognizing it on the plant label is important.

Determinate tomatoes generally produce all of their fruit at the same time. If you are planning to can tomatoes, these are the ones for you. You usually get about two weeks of tomatoes out of a plant. If you have a small space to work with, especially if container gardening, these might be the best choice as they are pretty compact plants.

Indeterminate tomatoes produce fruit all season long, which could be from May to October in some regions. These plants need a lot of space to grow as their vines spread out a lot. You’ll need to stake or cage them for best results, but you can just let them grow wild as a bush.

How to grow tomatoes

Tomatoes are relatively easy crops to grow according to some people. They aren’t as easy as growing bush beans or potatoes in my opinion however. Tomatoes require full sun, well draining soil and even watering. While you can grow tomatoes from seed, gardeners generally use transplants. Plant tomatoes 30 to 48 inches (76cm-122cm) apart in rows that are 4 feet (1.2m) away. It sounds very far apart, but when hornworms and disease inflict one, it will be more likely to pass to nearby plants. Keeping them spaced out can make a huge difference. Dig a hole that is larger than you think you’ll need. Tomatoes should be buried quite a bit in order for them to develop strong roots. Most gardeners will plant them so that the bottom set of leaves are just slightly above ground level. Use a mixture of compost and soil and then top with slow release fertilizer granules. Finally, place mulch around the plant to help it keep even moisture levels. I like to use straw for mulch because as it deteriorates, it adds organic matter back into the soil. You can choose any type of mulch you like though, including newspapers.

You’ll want to stake or cage your tomatoes after they are all set in the ground. This is to keep fruit off of the ground where it would be likely to rot. Staked plants take up less space then caged ones, but the plants are more stressed as this is not their natural way of growing. To stake a plant, simply use something tall and strong to tie the tomato plant to. You’ll need to prune staked tomatoes throughout the growing season. Tomatoes that are caged tend to produce more fruit. They are free to grow as they naturally would, but the fruit is kept off the ground and there is more air circulation to prevent disease. You can purchase ready-made cages at local garden centers when you buy your transplants, or you can make your own. We chose to make our own. One great thing about caged tomatoes is that they do not need to be pruned, which means less work. Many gardeners choose to pick suckers off however. These are the little shoots that form in the necks of the stems. Removing them lets the plant use energy in producing fruit more. Make sure to water the tomato plants evenly to prevent blossom end rot (more on this next). Tomatoes need about an inch of water a week. They prefer a deep watering twice a week, and possibly more with hot temperatures, rather than frequent short waterings. Make sure to add a bit of fertilizer again when the first set of fruit forms. Look for one low in nitrogen but high in phosphate. These usually have numbers on them like 4-12-4 or 5-20-5. I use a fish emulsion mix. Don’t over fertilize or you will have amazing green foliage, but little fruit.

Tomato diseases

Things can be going great and then one morning you check on your tomatoes and find they have black bottoms. What is it? That’s blossom end rot, a deficiency in calcium. It is caused by uneven watering. Luckily, it isn’t the end of the world, or your tomato dreams. You can correct the problem by making sure to water evenly. Don’t let the soil completely dry out.

Early blight is a fungus disease. You can identify it by looking at the leaves. They will develop yellow spots on them first, usually on the lower leaves. Then the leaves will become completely yellow. The whole plant turns brown in time. At the first sign, you can remove the damaged leaves and apply fungicide.

Bacterial spot is a disease that is caused by a bacterium. It is found on green tomatoes during the wet season. The fruit usually has small raised dark spots with yellow circles around them. It can be treated with a copper fungicide. The disease will linger over winter, so make sure to clear the area of all plant debris at the end of the season.

Pith necrosis is another early season disease. It is caused by multiple species of bacteria. The stems will have black portions that tend to be opposite of leaf petioles. As the bacteria spreads, the stems can split and break. This will prevent water from reaching the higher leaves causing them to yellow and wilt. Plants can recover as the season continues, but if they don’t you’ll need to remove them. Over use of fertilizer can exacerbate the problem. There are no treatments for this disease unfortunately.

Bacterial wilt, also known as Southern bacterial blight, is a disease that can linger in soil for a long time. The disease enters the plant through the roots and the stem fills with slime from the bacteria that quickly multiplies as the temperatures heat up. The plant will wilt but the leaves stay green. To check if your tomato plant is suffering from bacterial wilt, cut a stem. If it does have this disease, the inside will be brown and you’ll see yellow slime. Bacterial wilt can’t be treated with chemicals. You’ll need to pull the plant and discard it. Don’t put it in the compost pile. The bacteria will still be in the soil so proper crop rotation is important. Choose plants that are not susceptible to the disease such as beans, cabbage and corn. Don’t plant eggplant, potatoes, peppers, sunflowers or cosmos in this area for the next three years. Make sure you only plant certified disease-free plants.

Late blight usually develops in cooler weather, towards the end of the growing season. You’ll notice small dark lesions on young leaves that quickly spread and grow larger. White mold will form on the base of the leaves. Within 14 days, the whole plant will turn brown. The tomatoes become shiny and have dark lesions. The disease can spread to other plants so it’s important to remove the plant when you first notice signs of the disease.

Septoria Leaf Spot is a fungus that affects the leaves and stems of the plant, but not the fruit. The leaves near the ground will have circles with dark outer rims and a tan center. The black dot in the middle is where the disease spores are produced. This usually occurs when the plant sets fruit. Eventually, the leaves will turn yellow and fall off. You can treat this with a copper fungicide. A three year crop rotation is ideal, even though the fungus is not soil-borne, because it can overwinter on crop residue.

Leaf mold is a fungus that develops on the lower leaves as light green or yellow spots. The humidity plays a big part in the growth. When the humidity is high, those spots become covered with a velvety gray substance, which are the spores from the fungus. The leaves can die from this. Stems and fruit are occasionally affected by it. Black rot by the stem is a key indicator. The disease can spread with wind and rain and the humidity will make it develop quicker. Prune the lower levels of the plant to increase air circulation and treat with a fungicide. Discard the entire plant at the end of the season and practice crop rotation with plants that are not in the nightshade family for the next three years.

Other tomato disorders

Cracked tomatoes are common. The cracks occur during growth when the humidity is high during the day and then the temperature drops at night or when it has been very dry and then a heavy rainfall occurs. The fruit cracks as it expands.

Sunsculd usually happens when the tomatoes are still green. It is a burned spot from direct sunlight. Over pruning tomato plants can cause this.

Catfacing happens when fruit is formed when the temperatures are still low. As the season warms, the fruit that grows will not have this deformation.

Leaf roll or curled up leaves, happens when the temperatures are high and the soil is dry. This is usually when the plant is stressed by heavy fruit and over pruning.

Pests

Spider mites can be a problem. You can remove them by knocking them off the plant with high pressure water. Stink bugs are a more common pest. They suck the juice out of tomatoes and leave a leathery skinned tomato. I generally hand pick them off. Aphids are usually found on the bottom side of leaves. I place yellow sticky cards near the leaves to catch them. I also spray a neem oil mixture to rid the plant of them. The biggest tomato pest however are hornworms. They are large caterpillars that have perfect camouflage and can be hard to see. They will devour a tomato plant quickly and must be removed. I hand pick them off and relocate them in the surrounding forest.

While it sounds like tomatoes can be a lot of work and have a lot of problems with diseases, deformities and pests, growing tomatoes can actually be a great experience. They are a delicious fruit perfect for summer salads and canned for winter stews. Try a few different varieties to bring an abundance of color to your garden.