Wondering if your tomato plant will set fruit? Knowing how to tell if tomato flower is pollinated is a key skill for any gardener. This simple visual inspection guide will show you exactly what to look for, so you can stop guessing and start growing with confidence.
Tomato flowers are self-fertile, meaning they contain both male and female parts. For fruit to develop, pollen simply needs to move from the anthers to the stigma within the same flower. While wind and insects help, you can often see the results of successful pollination with your own eyes within a few days.
How to Tell if Tomato Flower Is Pollinated
The most reliable method is a simple visual check. You don’t need special tools, just a bit of patience and observation. The changes are subtle but clear once you know what your looking for.
The 3 Main Signs of a Pollinated Tomato Flower
After pollination occurs, the flower begins its transformation into a fruit. Here are the three clearest indicators to watch for.
1. The Flower Wilts and Dries Up
This is the number one sign. A successfully pollinated flower will start to wither from the center outward. The yellow petals will dry, turn brown, and may fall off. This is a good thing! It means the plant’s energy is now directed toward the tiny fruit behind the flower.
An unpollinated flower often drops off entirely while still looking relatively fresh and yellow. If you see a whole, bright yellow flower on the soil, it likely wasn’t pollinated.
2. The Base Swells (The Fruit “Bulge”)
Look closely at the green base of the flower, called the ovary. This is the part that will become the tomato. After pollination, you will see a small but noticeable swelling at this base. It starts as a tiny green bump right behind the dried flower remnants.
Within a week, this bulge will be unmistakable. It’s the baby tomato beginning to form. If the base remains thin and straight, pollination probably did not occur.
3. The Stem Thickens and Strengthens
The short stem (pedicel) that connects the flower to the main branch will also change. After successful pollination, this stem thickens and becomes more rigid. It needs to get stronger to support the growing fruit’s weight.
An unpollinated flower often has a thin, weak stem that eventually forms an abscission layer, causing the whole flower to drop cleanly.
Step-by-Step Inspection Routine
- Choose Your Time: Inspect plants in the morning when they are dry. Check flowers that have been open for 2-3 days.
- Look at the Flower: Is it still vibrant and open, or is it starting to close up and look tired? Drying petals are your first clue.
- Examine the Base: Gently lift the flower and look at the green star-shaped base. Can you see a small, round swelling? Compare it to a brand new flower to see the difference.
- Check the Stem: Feel the short stem. Does it feel sturdy, or thin and fragile?
- Mark Your Progress: Use a little piece of colored string to gently tie near pollinated flowers. This helps you track growth over time and is great for teaching kids.
What Unpollinated Flowers Look Like
It’s just as important to recognize failure. An unpollinated flower typically:
- Stays open and yellow for several days without change.
- Falls off the plant completely, often with a gentle touch or breeze.
- Shows no swelling at the base whatsoever.
- The entire flower structure detaches, leaving no tiny fruit behind.
Don’t worry if some flowers drop. It’s normal, especially for the first few clusters or during extreme heat.
How to Improve Pollination Rates
If you’re seeing too many unpollinated flowers, you can easily help. Here are the best methods.
Gentle Plant Tapping
Every day or two, simply tap or shake the main stem or flowering branches for a few seconds. This mimics wind and dislodges pollen inside the flower. A vibrating toothbrush held against a flower truss works amazingly well too.
Encourage Helpful Insects
Plant pollinator-friendly flowers like basil, marigolds, or borage near your tomatoes. Bumblebees are especially effective at “buzz pollination,” which vibrates pollen loose perfectly.
Control Temperature and Humidity
Tomato pollen becomes sticky and ineffective in high humidity. It also fails to set in extreme heat (above 85°F/29°C at night) or cold (below 55°F/13°C). Proper watering and providing afternoon shade in hot climates can make a huge difference.
Use a Small Brush
For a few precious plants, a small, soft artist’s brush can be used to gently swirl inside open flowers, transferring pollen manually. Do this during mid-morning hours.
Troubleshooting: Common Problems & Solutions
Even with signs of pollination, sometimes fruit doesn’t develop. Here’s what might go wrong.
- Flower Dries But No Fruit: The tiny fruit may have aborted due to stress like inconsistent watering, a heat wave, or lack of nutrients. The plant sacrifices fruit to survive.
- Blossom Drop: When whole flower clusters fall off, it’s usually due to temperature extremes or too much nitrogen fertilizer which promotes leafy growth instead of fruit.
- Very Slow Swelling: Cool weather slows growth dramatically. Be patient. Also ensure plants have enough phosphorus and potassium, which support fruiting.
FAQ: Your Pollination Questions Answered
How long after pollination do you see tomatoes?
You can usually see the tiny fruit bulge within 5-7 days. It takes about 45-60 days from pollination to ripe fruit, depending on the variety.
Can a tomato flower pollinate itself?
Yes, tomatoes are self-pollinating. But they often need vibration (from wind or insects) to release the pollen within the flower.
What time of day do tomatoes pollinate?
Pollen is most viable in the late morning, after the dew has dried but before the afternoon heat. This is the best time to check flowers or assist pollination.
Should I remove unpollinated flowers?
You don’t have to. The plant will shed them naturally. Removing them won’t harm the plant, but it’s usually unnecessary work.
Why are my tomato flowers not pollinating?
The top three reasons are: 1) High heat or humidity, 2) Lack of air movement (plants too crowded or in a still greenhouse), 3) Insufficient plant vigor from poor soil or watering.
Final Tips for Success
Regular observation is your greatest tool. Make checking your tomato flowers part of your daily garden walk. The more you look, the easier it becomes to spot those critical early signs of swelling.
Remember that healthy, unstressed plants pollinate best. Provide consistent water, good soil nutrition, and proper spacing for air flow. If your weather turns very hot, a little shade cloth during the peak afternoon sun can help pollen stay viable.
With this visual guide, you can now confidently identify pollinated flowers and understand the simple process. This knowledge takes the mystery out of tomato growing and lets you support your plants more effectively for a great harvest.