Now that the weather is getting warmer, it is finally periwinkle time. Periwinkles are a great annual that thrive in our hot summers and keep going into the fall. My mother has a periwinkle hanging basket my sister gave her last summer that stills looks great!!
An irritating issue with periwinkles is they can get stem rot, a bad disease problem for periwinkles. The variety we sell, Cora, is less susceptible to stem rot than the older varieties, but can still get it. This disease is caused by a soil-borne, fungal-like microorganism, phytophthora, that can persist in the soil for years. Under conditions of overhead watering or heavy rainfall, this disease can spread rapidly throughout your periwinkle planting beds.
To minimize the possibility of this disease there are a few steps you can take to help prevent it from occurring. Be sure to work compost into the soil to help loosen the ground for better drainage. Space the plants 8-10 inches apart. Mulch heavily with hardwood mulch.
Slow easy watering with a soaker hose or drip irrigation at the base of the plants is best instead of overhead irrigating. Hand watering carefully to saturate the soil around the plants without watering directly over the top is also advisable. If you have had stem rot or want to insure success, water your plantings in with Actinovate Fungicide. All these tips will help you be successful with periwinkles!