A summer garden without tomatoes is like rhubarb without strawberries! The tangy-sweet refreshing taste of a garden-fresh BLT or a cherry tomato salad is unmatched. But a tomato plant without flowers cannot produce fruit.
If you don’t see any star-like yellow blossoms on your tomato plants by early summer, it’s a sign that something is awry. Like all organisms, tomatoes need their basic needs met before they can reproduce.
The absence of flowers means your tomato plant isn’t getting what it needs to survive. Let’s dig into everything you need to know about why your tomato plant lacks flowers and how to fix it!
The Quick Answer
If your tomato plant doesn’t have any yellow star-like flowers, it is probably under some form of stress. When a tomato doesn’t have proper temperature, sunlight, water, and nutrition, it isn’t able to produce flowers. Without flowers, there is no fruit. The primary causes for tomatoes without flowers are:
- Temperature fluctuations: Tomatoes prefer to set blooms in mild temperatures between 65°F and 80°F. Cold nights below 50°F or long hot days above 90°F can cause tomatoes to limit bloom production.
- Insufficient sunlight: Tomatoes demand at least 6-8 hours of direct sunshine per day. Without enough light, the plant leaves cannot produce enough energy to grow flowers.
- Water stress: Tomatoes are notoriously thirsty crops that need 1-2” of water per week during the flowering period. If the plant doesn’t have enough water, it won’t be able to uptake the nutrients needed for floral production. It will conserve its energy for leaves and stems. If the plant is overwatered, it may wilt or turn yellow and develop a disease that prevents flowers.
- Nutrient issues: An excess of nitrogen in the soil can overstimulate foliage growth at the expense of flower production. Similarly, low fertility may not be enough to support bloom production.
The Detailed Answer
There are a number of different reasons your plants may not bloom.
If your tomato plant isn’t flowering, it is not receiving the proper temperature, light, nutrients, or water that it needs to blossom. All plants, animals, and humans have a baseline of foundational needs.
When you don’t get enough nutrition, your body cannot focus on advanced functions like high-level thinking or reproduction because it is stuck in survival mode. Tomatoes are the same way.
Tomatoes typically begin flowering about 1 month after they are transplanted in the ground. Small yellow flowers first develop on plants that are 12-18” tall and should continue appearing throughout the summer as the weather permits. If your plant isn’t producing any flowers, it is trying to tell you something!
Fixing tomato flowering issues requires getting down to the root cause. Fortunately, most of them are easy to fix. Use a process of elimination to identify and correct the following issues that could be preventing your tomatoes from blooming:
Swings with hotter temps and lower temps can cause problems for tomato plants.
As natives of South and Central America, tomatoes obviously love the warmth. The minimum temperature for healthy growth is 55°F. Any extended periods of cold below 50°F can cause issues with flowering.
Although tomatoes can technically tolerate chilly temperatures, prolonged exposure sends them into survival mode. If your garden has faced a succession of cold nights, the tomato plants may be preserving their energy by abstaining from flower production.
On the flip side, tomatoes have trouble producing flowers in extreme heat above 90°F. In ultra-hot temperatures, tomatoes often drop their flowers to protect the rest of the plant. This is particularly problematic when the plant isn’t getting enough water.
You may find withered, dry flowers on the soil surface. If an extreme heat wave continues, they may not produce any flowers at all. You can also choose tomato varieties that are specifically created for warmer climates. As outlined in the video below, making sure the temperatures are just right for your hardiness zone is critical.
How to Identify
Monitor your nightly temperatures and take note of the floral situation. A complete absence of flowers usually means it is too cold. Dead flowers that have fallen at the base of the plant are typically a sign of too much heat.
Fixing the Problem
Row cover and shade cloth are your best bet for stabilizing tomato temperatures. You cannot control the weather, but you can do your best to buffer against extremes.
Temperature Fluctuation Tips
|Cold Protection||Cold nights can be remedied with hoops and row cover protection over the plants. Depending on the thickness of the row cover fabric, you can add an extra 2-6°F of protection for tomato flowers. If your area is super cold, you may want to build a hoop house for your tomatoes. You can also choose cold-tolerant tomatoes developed by high-elevation farmers.|
|Cooling Off||For extra hot climates, a different type of fabric called shade cloth can help block out excessive sun rays, but try to avoid any shade cloth ratings above 40% shade as they do need sunlight! You can also use misters to lightly water the plants during the heat of the day and lower the temperatures. If you repeatedly have trouble with flower-less tomatoes in mid-summer, consider planting them earlier or later in the season.|
If you don’t provide sufficient sunlight, it can impact bloom and fruit production.
Tomato plants are real wimps in the shade. These sunshine lovers demand full, direct sunlight for a minimum of 6 to 8 hours per day. Without enough light, the plant cannot photosynthesize properly, which means it lacks the energy necessary for flowering.
How to Identify
The key symptom of low sunlight is long, leggy, spindly tomato growth. You may notice elongated, weak stems with pale leaves. If there are any flowers, they usually look small and weak.
Fixing the Problem
Saving a shaded tomato requires transplanting or the addition of grow lights. There is no way around this. If growing in containers, move your tomatoes to an area with direct sunlight. If growing outdoors, check to see if any nearby shrubs or trees are shading the plants out. Prune or remove as needed.
If the plant is being shaded by a structure, you will need to use a shovel to dig it up and transplant it to a brighter location. In extreme cases, your plant may need some time to adjust to the new environment. A light row cover or light shade cloth can be useful for preventing sunburnt leaves as the tomato acclimates to the sunlight it has been craving.
Shallow Watering or Overwatering
Both overwatering and shallow watering can cause a lack of blooms.
Irrigating tomatoes can feel intimidating because it requires finding a happy medium. Consistency is key: the soil should never totally dry out, nor should it be a soggy pool of water.
If you water too little or too shallowly, the plant won’t have enough moisture to grow blossoms and fruit. But if you overwater, the plant can have problems with nutrient uptake, root rot, and other pathogens.
How to Identify
Underwatered and overwatered tomatoes typically show the same symptoms— the leaves appear wilted, droopy, yellow, and often curled at the tips or edges. They will grow very slowly, and flowers will not develop. You need to check the soil to get the full picture of what is going on.
Fixing the Problem
If the soil surface appears dusty, hard, and cracked, you need to water deeply and incorporate compost. If the soil is soggy, mushy, or has algae growing on the surface, back off the watering and potentially aerate the soil with a broadfork or hoeing on the surface. Once the soil has been re-moistened or dried out, you can restart your watering routine.
Irrigate tomatoes once or twice a week using a hose at the base of the plant or a drip irrigation line. Avoid sprinklers or overhead watering, as these can cause foliar diseases. The ideal watering schedule for optimal flowering is deep watering at less frequent intervals.
In other words, it’s better to give the tomato plant a big drink once or twice a week. This allows the water to saturate the soil more deeply. Within a few weeks, the plant should start producing flowers.
Avoid watering small amounts every day. Shallow watering can stall flowering and keep the plant in a stressed state.
Proper nutrition is essential for tomatoes to produce flowers.
Excessive nitrogen fertilization is a common reason for lush, bushy tomato plants without flowers. The extra nitrogen in the soil fuels rapid leaf development at the expense of flower and fruit production.
A lack of nutrients can also cause tomatoes to delay flowering. If the plant is getting all of the minerals and nutrients it needs, it can only focus its energy on basic survival. Poor soils with low organic matter are most likely to cause nutrient deficiencies.
However, issues with shallow watering can also result in the unavailability of nutrients. Most tomato-friendly fertilizers are water-soluble, so the plant cannot uptake the fertilizer without proper moisture, ultimately leading to few or no flowers.
How to Identify
Lush, ultra-green plants with lots of foliage are the key sign of too much nitrogen. On the other end of the spectrum, nutrient deficiencies will appear as weak, slow growth and yellow or brown leaves.
Fixing the Problem
If you suspect you over-fertilized your tomatoes with nitrogen, you may need to apply potassium or phosphorus-rich fertilizer to support the flowering and fruiting phase. Prune off excess suckers and side branches. Then, side-dress with compost, kelp meal, bone meal, or a “flower and fruit” fertilizer blend.
If your plants seem to be nutrient deficient, water with a quickly available fertilizer like diluted fish emulsion. Then, side-dress with a tomato-specific all-purpose fertilizer blend. Microbially-rich compost or worm castings can help to make organic fertilizers more plant-available. The tomatoes should begin producing flowers within a month.
Tomatoes only produce flowers when they have the weather, sunlight, water, and nutrition they need to thrive. You can quickly correct issues with flowering by inspecting your plants and determining which of their needs aren’t being met.
After all, stressed people don’t have the energy for lavish dinners and big projects. Similarly, stressed plants don’t have the capacity to produce flowers and fruit.
Encourage your tomato to flower by:
- Buffering extreme temperatures with a row cover or shade cloth.
- Ensuring consistently moist soil that is never too dry nor too soggy.
- Planting tomatoes in a place where they get 6-8 hours of direct sunlight.
- Avoiding excess nitrogen fertilizer.
- Providing potassium and phosphorus fertilizer to encourage flowering.