If you’re experiencing flowers falling off sweet peas, the chances are it’s not caused by insects or disease. Instead, it’s likely to be caused by the weather and the environment.
Hot, sunny weather can lead to the soil around the plants becoming dry which can cause dropping of flowers. Both runner beans and sweat peas are prone to flower drop if the soil gets too dry.
Early in the season it’s more likely that we’ll experience warm days and cold nights which can have an impact on the plants. So, to stop this being a problem for your sweet peas, delay planting by about two weeks to reduce the likelihood of flowers dropping.
If there’s a temperature drop forecast, protect the young plants that are already outdoors. Also, be sure to harden off plants raised indoors before planting out.
Equally, ensure the water being used to give moisture isn’t icy cold because this can shock the plant and cause the flowers to drop too.
As a solution, remove any seedpods that are forming because this will direct the energy back into the plant’s growth, and keep watering deeply and well to moisten the soil. The trick is to water during the evenings when it’s cooler and ensure the soil is covered with mulch at about 10cm thick which will retain moisture, insulate the roots, and suppress weeds.