A frustrated gardenerd wrote in recently:
“Having a little gardening crisis – I planted a second round of zucchini and cucumbers in September. They are large now and have produced many flowers, but no fruit! Other things I planted at the same time are doing well. Beans and peas aplenty. I know pollination is an issue, since what few bees there are right now are OBSESSED with the eucalyptus tree on the other side of the house, not my garden – but I’ve added some sweet alyssum pots to the garden area, and even poked at the flowers with a paintbrush. Still no fruit. Is there another possible culprit?”
Since cucumbers and zucchini both belong to the squash family, there are a couple things that might be playing a role in your gardening crisis:
1) Temperature change – if it gets below 60 degrees, squash plants don’t really like it. September is usually when temperatures start to drop toward fall climates. In Southern California, we had heat waves through mid-November though, so that might not be your problem. Still, if it got below 60 at night, it could be a contributing factor.
2) Check your soil for potassium levels. Potassium is one of the three essential nutrients in the NPK trio. It is responsible for fruit and flower development. If your levels are low, this could be preventing your squash from setting fruit. You can get a simple NPK test kit from most nurseries, or order one online like this:
It tests not only NPK, but pH as well. Squash like to have a pH between 5.5 – 6.8.
I hope this helps. Thanks for writing in and keep those questions coming.