While I knew that cool nights weren’t good for sweet peppers, I didn’t realize how early those cool nights were able to influence pepper size and development
Turns out that a cool night when the blossoms are forming or about to open (yes, that early in the development) causes the ovary to swell up and disfigure the pepper. Some never develop properly at all
The night-time temperature of deformation was around 12C (56F) so you really do want warm nights or great protection for this crop.
The use of frost-fabric right through the first flowering stage would seem to be the trick here, particularly in a cold season.
From HortScience 2011;46 396-401
I got this question the other day, “Why are there no flowers on my squash plants?”
Okay, there are several problems when your squash plants have flowers but no fruit.
Is it early in the season?
Take a look at the blossoms.
- If there is a tiny squash behind the blossom, it is a female bloom.
- If there is no tiny squash behind the blossom, it is a male bloom.
On many older varieties, there is a flush of male blooms before the females. There is some thought that these male blooms emerge to entice bees to visit and change them from whatever color they are harvesting, to yellow.
Note that bees tend to harvest pollen from one color flower at a time. It’s not as if the hive goes out and looks for everything, it is that they focus on collecting flowers of one color at a time.
Is it a damp spring?
If the spring is cool and damp, it is quite possible the female flowers are rotting off and not being properly pollinated.
My plants do not have any flowers and it’s July!
This is not unusual following a cold or damp spring. Remember that the squash family is a heat-loving plant family and cooler weather will slow them way down.
If it’s later in July, is also possible that too-high nitrogen fertilization has encouraged leaf growth and discouraged flower and fruit setting. This is a simple mistake to make with squash plants.
The check here is whether the plants are large and appear to be growing well (too much nitrogen) but there are no flowers.
The other thing to check on is the amount of sunshine the plants are getting. Remember this is a full sun plant and should not be in the shade at all.
Do the leaves look as if they have been dusted with baby powder?
If this is the case, your plants are stressed and weakened with powdery mildew.
Powdery mildew is caused by high humidity even when the plant foliage is dry. Light levels are generally low – as in the early spring – and temperatures are average for your season.
You will see this problem when your evenings are cool and your days are getting warmer and humid.
Those are the main reasons for not seeing flowers on your squash plants.