Homegrown: Late growing season
We planted zucchini squash and cucumber seeds last summer, and we had lovely plants with lots of leaves, plenty of blossoms, but no fruit (one or two is all). What did we do wrong? Do we need to amend the soil? I’m not sure what to do to have a great season next year.
What you experienced wasn’t all that unusual this past year.
I think part of the problem was that the growing season was later than usual. April into May was cool delaying the squash, which like lots of hot weather and warm soil.
The plants just didn’t have the normal head start they have most years.
Now, that doesn’t explain your problem completely. Most of the problem of poor fruit set is because of poor pollenization of the flowers.
Squash have what are called “imperfect” flowers, that is, they don’t have all the parts a “perfect” flower has. Some flowers have the male parts (stamen), and some have the female parts (pistil). This means that there are male flowers and female flowers. Obviously, you need both for fruit to form, but you will only get fruit from the female flower.
When the plant starts flowering, it usually only puts out one type of flower. I usually only see male flowers at first with the female flowers following a couple of weeks later.
This might explain why no fruit is set on the plant at first even though it started to flower. This happens pretty much on all squash plants. However, the plant usually starts producing once both types of flowers appear.
The type of flower is easy to identify. On a male flower, the thin stem that holds the flower stays thin and cylindrical right into the base of the flower. With a female flower the stem will swell right at the base with a little miniature version of the mature fruit.
The male flowers are almost always more numerous than the females, usually outnumbering females by up to 10 to one.
The flowers usually only last one day. They open up in the morning and close up in the afternoon as it starts getting hot.
A plant that continually does not bear fruit is usually having a problem with the agents of pollenization—the bees (and sometimes flies) that transfer the pollen from the male flower to the female flower.
Honeybees are common pollinators of squash, and their numbers have been dropping the past eight to 10 years. Researchers think that there may some viral agents causing this, but whatever is going on, a lack of bees can lead to poor fruit set.
Native bees also pollinate. Most of these are solitary insects that dig burrows in the ground to nest. Having these little insects around will ensure good crops of squash.
These mining bees need a suitable area to dig their burrows. First, they need exposed soil. Having every square foot of the yard covered with heavy mulch or turf will reduce their numbers.
They also like soil that’s a bit looser or sandier with better drainage than not. This is why we see more evidence or leaf cutter bees (a burrowing type bee) out on the Redlands than in other parts of the valley. Providing a small spot in the yard can help increase their numbers.
The last thing that can contribute to low pollinator numbers is over spraying, which kills them.
I’m a fan of chemical sprays, but don’t overuse them. Spray only when necessary, and don’t spray in the morning when the bees are active. Early evening is probably the best.
Sorry, I can’t give you real specifics of what may be going on, but I hope this helps.