Tomato FAQs

You will need to start seeds indoors about 4 to 8 weeks before you plan to move the transplants outside. This gives them enough time to become sturdy seedlings.

Hardening off is the process of gradually acclimating indoor-grown transplants to outdoor conditions. Introduce them to more sunlight and wind each day over a period of 7-10 days before planting them in the ground.

The general rule of thumb is to wait until after the last expected frost date in your area and when the soil has warmed up. In many regions, this is after a key date like Memorial Day. Nighttime temperatures should be consistently above 55°F (13°C).

Tomatoes are sun lovers. They need at least six to eight hours of full, bright, direct sunlight per day. The amount of fruit you get is directly related to the amount of light the plant receives.

Tomatoes thrive in fertile, well-drained soil that is rich in organic matter, like compost or well-rotted manure. The ideal soil pH is slightly acidic, between 6.0 and 6.8.

Yes, soil sampling prior to planting is the best way to know exactly what nutrients your soil needs and to check the pH. It helps you make targeted amendments for a healthy crop.

You should plant them deep! Bury the stem up to the point where the topmost leaves begin. The buried stem will grow roots, creating a stronger root system. It’s okay for the stem to be planted at a slant if your hole isn’t deep enough.

Space your plants about 18-24 inches apart, with rows 3-4 feet apart. Good air circulation between plants is key to preventing disease.

Determinate (bush) tomatoes grow to a compact size and ripen their fruit all at once, making them good for containers and sauce-making. Indeterminate (vining) tomatoes grow and produce fruit continuously until killed by frost and need tall, sturdy supports.

For making sauce, look for paste tomatoes with dense, meaty flesh. ‘San Marzano’ is a classic, and ‘Ceylon’ is another excellent choice.

For a perfect slice on a sandwich or platter, heirloom varieties are hard to beat. ‘Sudduth’s Brandywine’, a pink tomato, is highly recommended.

The oblong shape of ‘San Marzano’ tomatoes makes them a perfect fit for canning jars, which is why they became the first commercially canned tomato.

Sweet and easy-to-pick cherry tomatoes are perfect for introducing kids to gardening. ‘Sungold’ is a popular, very sweet cherry variety. ‘Sara’s Galapagos’, a tiny currant tomato, is also exceptionally sweet.

This refers to the number of warm, sunny days a tomato plant needs to produce ripe fruit after being transplanted into the garden.

Absolutely! Choose a bush or container variety. For larger, indeterminate varieties, you will need a large container, at least 10 gallons in size and 18 inches deep.

Crop rotation means not planting tomatoes (or other nightshades like peppers and potatoes) in the same spot year after year. This practice helps prevent soil-borne diseases like Fusarium and Verticillium wilt from building up in the soil.

Look for stocky, dark green plants with thick stems. Avoid plants that are already flowering or have yellowing leaves, as they may be stressed.

Yes, especially indeterminate varieties. Support structures like stakes, cages, or trellises keep fruit off the ground (reducing rot and pests), improve air circulation, and make harvesting easier. Install them at planting time to avoid damaging roots later.

Common companions include basil (said to improve flavor), marigolds (to deter pests), and carrots. Avoid planting them near corn or potatoes.

Tomatoes need about 1 to 2 inches of water per week from a combination of rainfall and irrigation. They prefer an even supply of moisture rather than a heavy soaking followed by a drought.

Water deeply and regularly, at least once a week. During hot, windy weather, or if your soil is sandy, you may need to water more often. Container plants in hot climates may need water up to twice a day.

Water at the base of the plant to keep the foliage dry. Avoid overhead watering late in the day, as wet leaves promote fungal diseases. Early morning is the best time to water.

The key is consistent soil moisture. Blossom end rot is caused by a calcium deficiency in the fruit, often due to fluctuating water levels (drought followed by heavy rain) that prevent the plant from taking up calcium from the soil. Mulch helps maintain even moisture.

Yes. This is very common. The problem is usually water-related, not a lack of calcium in the soil. The plant needs consistent water to transport the calcium that’s already there.

That is classic blossom end rot. It appears as a greenish-brown to black, sunken, leathery area at the blossom end (the bottom) of the fruit.

Yes, the unaffected part of the fruit is safe to eat if you pick it early. However, you should remove the affected fruits from the vine to prevent them from attracting fungal or bacterial infections.

Start by incorporating a complete, balanced fertilizer (like 10-10-10) into the soil before planting. You can also use a starter solution higher in phosphorus (like 5-10-5) to promote strong root growth.

Once the fruits are about the size of a quarter, make a second fertilizer application. At this stage, you can side-dress with about 1 lb of 10-10-10 per 100 square feet, focusing on nitrogen to support fruit growth.

Tomatoes need a balance of nitrogen (N) for leaves, phosphorus (P) for roots and flowers, and potassium (K) for overall health and fruit development. Potassium is especially important for strong fruit skin and reducing cracking.

Mulching with straw, shredded leaves, or cardboard helps conserve soil moisture, keeps the soil temperature more consistent, suppresses weeds, and prevents soil from splashing onto lower leaves (which can spread disease).

Yes, pruning helps manage plant structure and focus energy on fruit production, especially for indeterminate varieties. Pinch out the “suckers” that grow in the crotches between the main stem and leaves.

Suckers are small shoots that grow in the leaf axils (the joint where the leaf meets the main stem). If left unpruned, they will grow into another main stem, making the plant bushier.

Pinch or snap them off when they are small, about 2 to 3 inches long. If they get larger than 4 inches, it’s better to leave them, as removing them can stress the plant.

On determinate (bush) varieties, only remove suckers below the first flower cluster. On indeterminate (vining) varieties, you can remove all suckers below the second flower cluster to encourage stronger main stems.

Pruning indeterminate plants to a few main stems (2-4) focuses the plant’s energy into producing fruit on those stems. Ensuring consistent water and full sun are also key to maximizing yield.

About a month before the first expected fall frost, you can pinch out the growing tip at the top of each main stem. This stops the plant from growing taller and forces it to put all its remaining energy into ripening the existing fruit.

In sandy soils, tomatoes can benefit from an application of Epsom salts, which supply sulfur and magnesium, two nutrients essential for plant growth.

This is usually due to temperature stress. Daytime temperatures above 90°F (32°C), or nighttime temperatures below 55°F (13°C) or above 75°F (24°C), can cause blossoms to drop. High humidity can also be a factor.

In addition to temperature stress, a lack of pollination could be the cause. Tomatoes are pollinated by wind and insects. Extreme weather can reduce insect activity. Also, too much nitrogen fertilizer can lead to lush, leafy growth at the expense of flowers and fruit.

Cracking is mainly caused by fluctuating soil moisture, especially as tomatoes ripen. When heavy rain or irrigation follows a dry spell, the fruit swells faster than the skin can grow, causing it to split. Mulching helps prevent this.

Yes. There are radial cracks that run from the stem down the sides of the fruit, and concentric cracks that form in circles around the stem end.

Maintain consistent soil moisture with regular watering and a thick layer of organic mulch. Avoid high-nitrogen fertilizers and ensure your plants have adequate potassium, which strengthens skin.

Catfacing is a disorder that causes tomatoes to be grossly malformed, with puckered surfaces, dimples, crevices, and tan scar tissue, especially on the blossom end. The fruit is still edible.

The most common cause is cold stress (temperatures below 50°F or 10°C) during blossom development. It often affects the first fruits of the season. Thrips damage and excessive pruning can also contribute.

Sunscald appears as pale, sunken, or blistered areas on the side of the fruit that is exposed to direct, intense sunlight. It often occurs when plants have poor foliage coverage due to disease or over-pruning.

The best prevention is to maintain healthy, leafy plants that naturally shade the fruit. Avoid heavy pruning that removes too many leaves. In extreme heat, you can use shade cloth during the hottest part of the day.

This can be due to irregular watering or excessive heat. Consistent moisture and proper mulching are key.

Several factors can cause small fruit: high temperatures (above 90°F), too much shade, insufficient water, or a plant overloaded with fruit (overcropping) that can’t support them all to full size.

As mentioned in the flower drop section, temperature extremes are a primary cause. Other reasons include poor pollination, too much shade, and high nitrogen fertilization.

Green shoulders are the hard, green areas at the stem end of some tomatoes, even when the rest is ripe. This is a genetic trait in some heirloom varieties and is not a defect, though some gardeners prefer varieties that ripen uniformly.

The best flavor develops when tomatoes ripen fully on the vine. However, if frost threatens or a fruit is damaged, you can pick it at the “breaker stage” (when it just starts to show color) and it will continue to ripen indoors on a countertop.

This is often the work of flea beetles. They are small, jumping beetles that chew tiny, shot-like holes in the leaves. They rarely kill the plant but can spread viruses.

It’s most likely a tomato hornworm. These large caterpillars are voracious eaters and can defoliate a plant in a day. They are well-camouflaged but can be picked off by hand.

If you see a hornworm with what looks like white grains of rice on its back, leave it alone! Those are the cocoons of a beneficial braconid wasp. The wasp larvae eat the hornworm from the inside out, and the cocoons will hatch into more wasps to control future pests.

Hornworms glow under ultraviolet (UV) or blacklight. You can go out to your garden at night with a UV flashlight to easily spot them on the plants.

The tomato fruitworm (also known as corn earworm) is a common pest that burrows into the fruit, often going unnoticed until damage is done. They create entry holes that can lead to rot.

If fruitworms have been a problem, you can apply an appropriate insecticide (like one containing spinosad) beginning when plants first start to set fruit. Always follow label directions.

Hand-picking larger pests like hornworms is effective. For others, insecticidal soap, neem oil, and products containing Bacillus thuringiensis (Btk) are options. Always check they are labeled for use on tomatoes.

To protect bees and other beneficial insects, apply insecticides in the late afternoon or early evening when bees are no longer active. Choose targeted products over broad-spectrum ones when possible.

It could be early blight, a common fungal disease that causes leaf spots and eventually leaf loss. Warm, humid, and rainy conditions favor it.

Avoid overhead watering, water in the morning so leaves dry quickly, mulch to prevent soil splash, and ensure good air circulation by proper plant spacing. Remove affected leaves at the first sign.

This could be a sign of a soil-borne disease like Fusarium or Verticillium wilt. These fungal diseases attack the plant’s vascular system. Once infected, the best course is to remove and discard the plant and avoid planting tomatoes in that spot for several years.

This virus causes curled, mottled leaves (green and yellow patchwork) and can lead to fewer, unevenly ripened fruits. It is spread by handling, so smokers should wash hands thoroughly before working with tomatoes. There is no cure; remove infected plants.

Leaf curl can be caused by several things: physiological stress (heat, drought, wide temperature swings), herbicide damage, or a virus like Tomato Mosaic Virus. Check for other symptoms.

These are bacterial diseases that cause small, black spots on the fruit and leaves. They are spread by splashing water, so avoid overhead watering. Copper-based sprays can offer some protection but results can be inconsistent.

Fungicides can be used preventatively or at the first sign of fungal disease if the problem threatens to severely defoliate plants. Products containing chlorothalonil are common for fungal issues. Always follow label instructions.

Remove all plant debris from the garden. Do not compost it, as fungal diseases and pests can overwinter on the plant matter. Throw it away with your yard waste.

The best test is by feel. A ripe tomato will give slightly to a light squeeze. A tomato that feels soft is overripe. Color is also an indicator, but feel is more reliable.

Yes, tomatoes will continue to ripen after being picked, especially if they have begun to change color (the “breaker stage”). However, the best flavor develops when they ripen fully on the vine.

Never refrigerate fresh, ripe tomatoes! Cold temperatures ruin their texture and flavor. Store them at room temperature, out of direct sunlight, and eat them within a few days.

If you have an overabundance of very ripe tomatoes you can’t eat right away, refrigeration will stop the ripening process and extend their life by a few days, but they will lose some flavor and become mealy. It’s a last resort.

Choose seeds from your best, open-pollinated (not hybrid) tomato. Scoop out the seeds with the gel, place them in a jar of water for 2-3 days to ferment, then rinse, dry on a coffee filter, and store in a cool, dark place.

VPD stands for Vapor Pressure Deficit. It’s a measure of the combination of air temperature and humidity. It indicates how easily a plant can move water from its roots to its leaves. An ideal VPD helps the plant take up nutrients like calcium efficiently.

High heat (above 30°C/86°F) combined with low humidity can cause severe stress. Leaf temperatures can soar, fruit sizing is affected, and flowers may abort. It can also cause a type of sunburn on leaves called scorching.

Yes, when light intensity is extremely high (e.g., above 1200 joules), it can increase plant stress and contribute to problems like blossom end rot. Growers may use shade screens to manage this.

A “generative” plant is one that is strongly focused on reproduction (making fruit) but may be doing so at the expense of its own health. Signs include thin leaves, small, pale flowers, and reduced pollen. It’s often a stress response to too much fruit load or high temperatures.

This can be a sign of a root problem, like Pythium, especially if the growing medium (like rockwool) is staying too wet and not draining properly. Poor drainage can suffocate the roots and lead to wilt.

Commercial greenhouses often use a “string-and-weave” system where strings are dropped from overhead and wound around the plant as it grows. For home greenhouses, tall stakes or cages work well.

CO2 is essential for photosynthesis. In a sealed greenhouse, CO2 levels can drop as plants use it up. Enriching the air with CO2 can boost growth and yield, especially during times when vents are closed.

Those small bumps are root initials. They are perfectly normal. They are the plant’s attempt to grow roots from the stem, which is why we plant tomatoes deeply—so those bumps can turn into a stronger root system.

Some heirloom tomato varieties have leaves that are large, smooth-edged, and resemble potato leaves, as opposed to the more common “regular leaf” which is ruffled and lobed. It’s just a genetic variation.

These letters indicate a tomato variety’s resistance to common soil-borne diseases: V for Verticillium wilt, F for Fusarium wilt, and N for nematodes (microscopic root pests). Choosing VFN varieties is a great way to avoid disease problems.