7 Reasons Your Tomatoes Aren’t Setting Fruit This Season
Are your tomatoes struggling to set fruit this season, but you aren't quite sure why it happens? There are actually a few reasons that this can occur, and most are easily remedied. In this article, organic gardening expert Logan Hailey walks through the seven most common reasons your tomatoes may be failing to set fruit this season.
You carefully tended your tomato plants throughout the spring, but now they’re not showing any signs of producing actual tomatoes. This can be incredibly frustrating and confusing for gardeners of any skill level. While tomatoes are traditionally quite easy to grow, they still need specific conditions to produce those juicy summer fruits we all crave.
If your tomato plants are all-leaf and no tomatoes, you’ve probably got an issue with pollination, fertility, water, or weather. But the bigger question is – what do you do about it? Non-fruiting tomatoes is a common problem, and can be easy to fix.
Let’s dig deeper into the most common reasons why your tomato plants aren’t setting fruit and the best ways to address it once you’ve noticed it.
Tomato Life Cycle
Tomato plants are heat-loving annuals that love lots of water, nutrients, and sunshine. Their star-shaped yellow flowers require pollination by insects or wind in order to set fruit. When tomatoes are only growing foliage without producing fruits, it’s a sign that there aren’t enough pollinators or something is preventing the plant from fruiting.
Like all garden plants, tomatoes have two main parts of their lifecycle: the vegetative stage and the reproductive stage. For tomatoes, the vegetative stage is all about growing roots, stems, and leaves to get established after planting. This typically occurs in the spring time.
When the summer days start to get longer, tomatoes shift into their reproductive stage, which focuses on flower and fruit production. But if they are under any type of stress (water stress, disease, fertility problems, or extreme temperatures), they may not have the extra energy to fuel reproduction.
Why Tomatoes Won’t Set Fruit
Though its commonly known as a vegetable, tomatoes are actually a fruit. In the garden, tomato plants require certain conditions to produce those delicious slicers, heirlooms, or cherry tomatoes. But when things aren’t quite right, your plants may not put out flowers or fruits at all. Here’s why:
Lack of Pollination
Like many garden plants, tomatoes rely on bees or wind to pollinate their flowers. If you notice that your plants have an abundance of yellow blossoms that never seem to grow into fruit, you likely are lacking in pollinators.
A healthy garden ecosystem should have a continuous buzz of bees (both honeybees and native bees), butterflies, and other insects. Without habitat and food for these pollinators, your tomato flowers may be sitting idle waiting for their pollen to be spread.
Alternatively, extreme temperatures or humidity may be affecting pollinators’ ability to be active in your garden. If you usually have lots of bees but the weather has recently been unusually cold (below 40°F) or excessively hot (above 90°F), reference the section below regarding weather.
If your garden is particularly sheltered or your tomatoes are growing in a greenhouse, you may also be lacking in airflow that can blow pollen from flower to flower. For indoor tomatoes, add fans or roll up the sides of a hoop house to get a breeze.
The quickest solutions to a lack of pollination include the following.
On a warm, sunny day, use a toothbrush or pencil to shake or tap the interior of tomato flowers. You can also use your finger or a paintbrush. This stimulates the vibrations of a buzzing bee. Because tomato flowers are self-pollinating, they contain both male and female parts inside one blossom. The tapping will stimulate the plant to release pollen directly onto the stigma of the flower. Repeat daily for 2-3 days and flowers should begin to shrivel as fruits form.
You can purchase bumble bees or mason bees from beneficial insect sources or garden stores to help pollinate your tomatoes. Releasing these insects may be a temporary fix, but remember that they’ll need nearby floral resources to actually stick around your garden.
In the future, I always recommend planting tomatoes with pollinator-attracting plants like white alyssum, phacelia, tulsi basil, or marigolds.
It is also helpful to incorporate perennial flowering plants in the borders of your garden to help maintain a long-term food source for pollinators in your garden. You can also build native bee houses or raise some honeybees of your own!
Lack of Fertility
Without sufficient nutrition, tomatoes won’t have the energy they need to fuel fruit production. The reproductive (fruiting) phase is particularly dependent on potassium and phosphorus. Potassium promotes flower formation, while phosphorus increases fruit yields and ripening.
The most common sources of potassium fertilizer include:
- Kelp meal
- Hardwood ash (potash)
- Bird guano
- Mined rock powders
- Rotted manures
- Quality compost
Great sources of phosphorus include:
- Rock dust
- Bone meal
- Fish bone meal
- Manure-based compost
When plants start to flower, avoid feeding nitrogen and start adding a potassium and phosphorus fertilizer. I like to give tomato plants a bi-weekly dose of kelp fertilizer (liquid or granulated) side dressed by the base of the plant.
If you properly integrate nutrient-rich compost or a slow-release all-purpose organic fertilizer at the time of planting, this may not be necessary.
Too Much Nitrogen
If your tomatoes look massive and lush but they aren’t fruiting, you may be dealing with a fertility issue. While yellowing leaves and stunted growth can indicate a nitrogen deficiency, an abundance of foliage without any tomatoes is a common sign of nitrogen overdose.
This can also happen when the soil is too alkaline, leading to too much nitrogen availability in the soil.
Although tomato plants obviously need nitrogen to survive, this excess causes an overgrowth of leaves that prevents fruiting. Plants may look extra tall, leafy, and green without many flowers. The fertilizer imbalance can trigger the plant to channel most of its energy into producing more leaves rather than dedicating its efforts to fruiting.
Prevention is key for this tomato fruiting problem. You should only give your tomato plants a small dose of nitrogen at the time of planting. Organic fertilizers tend to be better because they are slow release and less likely to cause nitrogen overdose. Avoid using concentrated nitrates and always follow fertilizer package instructions.
If you’ve already over-fertilized your tomato plants, you can try flushing out some of the nitrogen with a deep watering or adding a carbon-rich mulch around the plants to help neutralize the soil.
Drought or Overwatering
Tomato fruits are over 90% water, so it should come as no surprise that watering issues can really hinder your tomato harvest. Your plants need plenty of water to fuel the transition from flowering to fruiting. Drought-stricken plants may look wilted, droopy, or yellow.
On the flip side, overwatering tomatoes can lead to root rot that stops plant growth altogether. As the tomato roots begin to suffocate and shrivel, they can’t uptake the nutrients or water they need to generate flowers and fruits. Overwatered tomatoes typically have yellowing or brown leaves and blisters or bumps on the lower foliage.
Tomatoes require about 1 inch of water per week. Check your tomatoes every few days to ensure they are getting plenty of moisture. You can use the “finger test” by putting a dry finger into the soil about 6” deep near the base of the plant:
The Finger Test
- If your finger comes out clean, the soil is way too dry.
- If it comes out with a little dirt stuck to your skin, the water level is good.
- If it comes out soggy, you may be overwatering.
Inconsistent watering can also cause blossom end rot and drought stress in tomato plants. It’s important to regulate your irrigation system or provide supplemental water during periods without rain. In dry climates, you can also add a straw or leaf mulch to help conserve moisture.
To prevent overwatering, always plant tomatoes in rich well-drained soil with plenty of organic matter. I like to use a broadfork and integrate quality compost before planting.
It should come as no surprise that sick plants don’t have the health and vigor to grow fruits. When tomatoes are diseased, the stress of fighting a pathogen takes away from the plant’s ability to grow plump juicy fruits. Some common tomato diseases include:
Also known as the pathogen that caused the Irish Potato Famine, this aggressive fungus can cause tomato plants to look like they have water-soaked leaves and purple blotches. While infected plants can still produce tomatoes, they are less likely to yield healthy fruit.
Hot dry weather and cool nights can lead to this mildewy infection overtaking tomato foliage. It looks like white flour has been dusted over the plants. As the stressed-out tomatoes try to fight the infection, they may not have the energy to produce flowers and fruits.
This fungus appears around the time the plant starts flowering, leading to bleached stems that look dried out and infected. It is most common in excessively wet conditions or high humidity. This can prevent fruit from forming.
Each tomato pathogen may require unique treatment, but there are several steps you can take to ensure resilient plants from the beginning:
- Grow tomatoes in biologically-rich soil with plenty of organic matter.
- Avoid overwatering tomatoes.
- Maintain plenty of air flow between your tomato plants.
- Avoid overhead irrigation of tomato plants whenever possible.
- Instead, use drip irrigation or soaker hoses to deliver water to the base.
When it comes to disease, prevention is always the best treatment. Ideally, you’ll provide hospitable growing conditions that can nurture a disease-free growing environment before your plants have any type of impact.
Tomatoes are notorious lovers of sunshine. When they don’t have enough light, their fruitset may be measly or completely non-existent. This is because the tomatoes don’t have sufficient photosynthetic energy to fuel their growth.
Photosynthesis requires sunlight, water, and minerals for the plant to generate the carbohydrates it needs to thrive. Tomatoes need at least 6 to 8 hours of direct sun every day in order to produce flowers and fruit.
Spindly or “leggy” tomato growth is a key symptom of insufficient light. As the plant struggles to fulfill its daily needs for photosynthesis, its stems may get longer and the leaves can grow paler While it may produce some flowers, they are less likely to grow into large, scrumptious tomatoes.
If your tomatoes are growing in containers, move them to an area with direct sunlight. If your garden is being shaded by shrubs or trees, consider pruning away some branches to allow more light in.
In the future, only plant tomatoes in the brightest area of the garden with uninterrupted sunlight throughout the summer season. While some types of tomatoes can thrive in the shade, most prefer sunlight.
Stress makes it hard to do anything— this is especially the case for tomatoes in extreme temperatures!
Tomatoes are warm-weather crops that can get pretty pathetic in the cold. Temperatures below 50°F can significantly stall tomato growth or kill the flowers. Flower drop is especially problematic in areas with high daytime temperatures and low nighttime temperatures. Without flowers, there is no fruit! Tomatoes prefer to fruit in temperatures between 60°F and 85°F.
Heat can also be an issue for tomatoes in the reproductive phase. It’s difficult for them to hold onto blooms when they’re under heat stress. During a scorching heat wave, they may spontaneously drop their flowers or stop producing them altogether. This is especially likely if they are under drought stress.
If you expect a cold front, protect your tomatoes with frost fabric or a low tunnel. In extremely hot or humid climates, search for southern heat-tolerant varieties that will still set fruit in the sweltering summer.
Tomatoes are naturally vigorous and easy to please, but they may not be ready to reproduce (grow fruit) if their basic needs aren’t being met. The most important things you can do to ensure your tomatoes produce fruit include:
- Plant tomato companion plants to attract pollinators.
- Ensure adequate airflow.
- Avoid excess nitrogen fertilizer.
- Maintain consistent moisture (neither under nor overwatering).
- Avoid overhead irrigation.
- Use mulch to conserve moisture and buffer against temperature extremes
- Grow in compost-rich, well-drained soil.
- Plant in an area with 6-8 hours of direct sunlight.
- Protect plants from extreme weather.
If your tomatoes are producing lots of flowers without any fruit, it’s probably a sign that they are stressed out or not receiving adequate pollination. Worst-case scenario, you can always hand-pollinate tomato flowers by shaking something around inside each flower to encourage pollen shed.