Why Are My Tomato Plants Flowering Early? (4 Main Reasons)


Are you worried by tomato plants that are flowering early?  If so, you are probably wondering what causes premature flowering and what you can do about it.

So, why are your tomato plants flowering early?  Tomato plants will flower early if you buy older transplants from a garden center or if you start your seeds too early. Also, some tomato varieties flower earlier in the season than others. Remember that soil temperature and nutrient levels can also affect when tomato plants will flower.

Of course, it would be nice to know exactly which of these things is causing your tomato plants to flower early.  In this article, we’ll examine some of the common causes and what you should do to address the issue in each case.

Let’s get started.

Why Are My Tomato Plants Flowering Early?

Sometimes, tomato plants will flower early – perhaps long before you expected them to.  This can be concerning, and it is natural that you want to solve the problem.

tomato flowers
There are many reasons that tomato plants may flower early. Start date and variety are two factors.

However, before we can do that, we need to find the exact cause. Some of the common causes of early flowering in tomato plants include:

  • Age (Start Date)
  • Variety (Determinate vs. Indeterminate – that is, early maturing or not)
  • Fruit Size
  • Temperature
  • Soil Nutrient Levels
Costoluto Genovese Tomato
Tomato plants with large fruit take longer to flower and produce fruit.

Let’s start off with a simple one that is easy to overlook: the date the plants were started (their age).

Start Date For Tomato Plants

After tomato plants reach a certain age and size, they will start to flower.  Of course, this will vary depending on several factors, including:

  • Weather (Temperature)
  • Soil (Nutrients, pH, etc.)
  • The variety of tomato plant (more on this later)
rain
Cool, rainy weather may delay tomato plant development and flowering.

However, if your tomato plants are older than you thought they were, they might start flowering a few weeks earlier than you expected.

Buying Tomato Transplants

Did you buy your tomato transplants from a garden center?  If so, then you have no way of knowing exactly how old they really are.

For one thing, some of the transplants that arrive at the garden center might be older than others (especially if they came from different suppliers).

tomato seedling
If you buy tomato transplants from a garden center or greenhouse, you don’t know exactly how old they are.

In addition, some of the tomato plants could have been sitting on the shelves for a week or two before you bought them.

The ideal tomato transplant is about 6 inches (15 centimeters) tall. It should also be free from any signs of disease (check for sick or weak looking plants, mold on the soil or stems/leaves, etc.)

tomato seedling
The ideal tomato transplant is about 6 inches tall and has no flowers.

Inspect your plants carefully before buying anything. A plant with a disease (such as blight) can spread the problem to other plants in your garden!

Avoid transplants that already have flowers on them, since they may be too old for transplant.

Starting Your Own Tomato Seeds

Did you start your own tomato seeds indoors?  If so, you might have started them too early without realizing it.

tomato plant 3-5-2021
If you started your own tomato seeds indoors, it may have been too early in the season. This can lead to early flowering.

According to the University of New Hampshire Extension, tomato seeds should be started indoors 6 to 8 weeks before being moved into the garden.

You should transplant your tomatoes into the garden after the last frost date in your area.  You can find frost dates by city or zip code with this tool from the Old Farmer’s Almanac.

frost
Frost is the main consideration for planting and transplanting tomatoes – as a subtropical plant, they cannot tolerate cold or frost.

If you happened to start your tomatoes indoors more than 8 weeks before the last frost date, then they might grow large and start flowering early.

This is more likely to happen with fast-maturing or early-maturing tomato varieties (more on this below).

Variety

There are hundreds of different tomato varieties to choose from.  They vary quite a bit in terms of size, flavor, time to maturity, disease resistance, and so forth.

One of the most basic distinctions for tomatoes is between determinate and indeterminate types.

Determinate & Indeterminate Tomatoes

Tomatoes fall into two basic categories:

  • Determinate – these varieties tend to be shorter (5 feet or under) and have a bush growth habit.  They produce fruit during a shorter window in the season, and they tend to produce earlier in the season.
  • Indeterminate – these varieties tend to be taller (6 feet or more) and have a vine growth habit.  They tend to produce fruit throughout the growing season, until frost stops them.
tomato plants with twine rope stake
Determinate tomato varieties are shorter, while indeterminate types grow taller.

According to Rutgers University:

“Determinate plants produce many short branches ending in flower clusters with a very brief harvest. They are seldom used in the garden except as early varieties, since most people want a long harvest season.”

https://njaes.rutgers.edu/fs678/

So, if you are growing determinate tomato varieties, then there is a chance that they will flower early.  In fact, they may flower much sooner than some of their indeterminate cousins.

(To see if you are growing a determinate variety, check on the seed packet label, which should tell you either “determinate” or “indeterminate”).

seed package
Check the seed packet (or in the catalog or online) to see if a tomato variety is determinate or indeterminate.

However, this doesn’t mean that all indeterminate varieties mature slowly.  Some indeterminate tomato varieties will flower and produce fruit early.  For example:

early girl tomatoes
Early Girl tomatoes grow fast – it takes them only 50 days to mature!
Image from: https://commons.wikimedia.org/wiki/File:Earlygirl.jpg

In addition to growth habit, the size of the fruit can also impact how long it takes a tomato plant to flower.

Size Of Fruit

Tomato varieties with larger fruit will take more time to flower and produce mature fruit.  For example:

brandywine tomatoes
Brandywine Pink tomatoes take 85 days to mature – a long wait for delicious fruit.

So, if you are used to growing large tomatoes that take a long time to mature, then smaller varieties may surprise you with their early flowering and fruiting.

For example, Early Girl tomatoes mature 5 weeks (35 days faster) than Brandywine Pink tomatoes! (50 days vs. 85 days after transplant).  One benefit of early tomato flowers and fruit is that you can avoid late spring or early fall frosts in areas with a short growing season (like Vermont and other northern regions).

Also, by choosing tomato varieties with smaller fruit, you may be able to avoid the problem of catfacingAccording to Rutgers University, catfacing is:

“Misshapened, severely deformed fruit, more common on the large fruited or early varieties, resulting from incomplete pollination of the tomato flower due to cold conditions when flowering. To minimize damage plant tomatoes after weather warms, avoid using large fruited varieties, and harden tomato transplants by limiting water, not by lowering temperatures. Catfaced tomatoes are safe to eat.”

https://njaes.rutgers.edu/fs678/

This quote also provides us with another hint about what may cause tomato plants to flower early: environmental conditions (such as temperature).

Temperature

If you transplant tomatoes into the garden and cool weather follows, their growth will be sluggish.  On the other hand, warm weather will encourage them to grow faster (tomatoes like warm temperatures – after all, they are subtropical in origin!).

If you keep your tomatoes in a greenhouse to harden them off, the warmth inside may encourage them to grow faster.  This is especially true in a year when spring temperatures are higher than normal.

greenhouse
Tomatoes grown in a greenhouse may flower sooner than ones grown outside.

In addition, the variety of tomato will also impact how temperature affects growth and flowering.  According to the University of Missouri Extension, different tomato varieties may also have different responses to temperatures.

Nutrients

The amount of nutrients that a plant gets may also impact when it flowers.  For example, according to the University of Missouri:

“Nitrogen nutrition also has been demonstrated by research to influence blossom drop. At high levels of nitrogen the plant is encouraged to produce excessive vegetative growth at the expense of fruit set. There is a fine line between having adequate amounts of nitrogen for good growth and excessive amounts.”

https://ipm.missouri.edu/MPG/2013/4/Understanding-Tomato-Fruit-Set/
tomato flowers
Too much nitrogen for a tomato plant may prevent or delay flowering.

So, it is possible that the use of more high-nitrogen fertilizer early on may prevent early flowering in tomato plants.  You can learn more about high-nitrogen fertilizers here.

Just be careful when applying these fertilizers.  Follow the directions, or else you can burn you plants by over fertilizing!

To avoid the problem of too much nitrogen when it is time for flowers to appear, check out my article on low-nitrogen fertilizers.

Can A Tomato Plant Have Too Many Flowers?

A tomato plant can have too many flowers, but usually the plant will solve this problem all by itself. A tomato plant with too many flowers will often drop the excess ones.

tomato flowers
If a tomato plant has too many flowers, it will usually drop the extra ones on its own.

This leaves behind only as many flowers as the plant can support to mature fruit.

Note: tomato flowers may also fall off if temperatures are too hot or too cold (more on this later).

Should I Pinch Early Tomato Flowers?

Generally, you should not pinch off early tomato flowers.

For one thing, tomatoes and other plants “know” how much fruit they can support to maturity.  They will take steps to remove extra flowers and fruit, if necessary.

tomato flower
Do not pinch off early tomato flowers. The plant will drop extra flowers on its own based on temperature and available resources.

For example, cool nights will cause tomato plants to drop blossoms on their own, when temperatures get below 55 degrees Fahrenheit (13 degrees Celsius).

Heat will also cause tomato plants to drop blossoms on their own, when temperatures get above 90 degrees Fahrenheit (32 degrees Celsius) for an extended time.

sunlight
On a hot day, tomato plants may drop some of their flowers.

In fact, according to the Oregon State University Extension:

“Some flower drop is normal.  Plants generally produce far more flowers than the amount of fruit or vegetables they can support.”

https://extension.oregonstate.edu/news/why-vegetables-drop-blossoms

So, tomato plants produce extra flowers as a hedge against any problems, such as a lack of pollinators or pests destroying some of their flowers.  Later, the plant gets rid of any extra flowers (this is comparable to June drop in fruit trees).

bee
A lack of pollinators can lead to reduced pollination, so tomato plants hedge their bets by producing more flowers.

If you think about it, it makes sense for plants to produce twice as many flowers as they need.  Then they can lose half, and still turn the other half into fruit.

The alternative is to possibly lose all of the flowers and produce no fruit at all! Remember that every flower you pinch off is one tomato fruit that you will not harvest.

heirloom tomato
Every tomato flowers is another potential fruit (assuming proper pollination, water, nutrients, etc.)

For determinate varieties, there are a limited number of flowers and fruit in the season.  So, it is not advisable to pinch off flowers from these varieties.

For indeterminate varieties, the plant will continue to grow, produce flowers, and set fruit until frost.  So, there is no point in getting rid of the flowers from these varieties either.

What To Do When Tomatoes Start Flowering

Once your tomatoes start flowering, there are some steps you can take to keep them alive and help them along.

Protect Tomato Plants From Cold & Frost

Protecting your tomato flowers from cold and frost will give them time for proper pollination. You can use cloches, row covers, or a greenhouse to protect tomatoes from cold in the spring.

row cover
Use a row cover (a thin, breathable piece of fabric) to protect tomato plants from cold.

You can learn more about how to protect your tomato plants from cold and frost in my article here.

However, cold temperatures may prevent bees from working.  Also, you might not have any wind if your plants are indoors.

In those cases, you may need to hand pollinate tomato flowers to help things along.

Hand Pollinate Your Tomato Plants

Normally, tomato plants are pollinated by vibrations from wind or from pollinators (such as bees).  However, this does not always happen if the air is calm, or if bees are not out yet.

electric toothbrush
An electric toothbrush is one way to pollinate tomato flowers by hand.

In those cases, you can use a toothbrush, tuning fork, or toothpick to pollinate your tomato plants by hand.  You can learn more about how to pollinate tomato plants by hand in my article here.

Blossom Set Spray For Tomato Flowers

Another option to get more fruit from your tomato flowers is to use blossom set spray.  It works by fooling tomatoes into producing fruit from flowers, even without natural pollination.

This method may be advisable if there is a lack of pollinators in your garden and you do not have time to pollinate by hand.

Just remember that fruit from blossom set spray will have few or no seeds (any seeds that do appear are probably sterile).

tomato seeds
Normally, tomatoes contain seeds. However, fruit that comes from blossom set spray might have no seeds at all.

You can learn more about how blossom set spray works in my article here.

Conclusion

Now you have a better idea of why your tomato plants are flowering early.  You also have some steps you can take to prevent the problem in the future.

You can learn more about what it means for tomato plants to be self-pollinating in my article here.

You might also be interested in reading my article on how long it takes tomato plants to bear fruit (from seed to mature fruit).

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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