Protect Gillyflower from disease and freezing temperatures.
image by cobalt123/Flickr.com
The gillyflower goes by several names, including garden stock, ten-week stock and Matthiola incana. It's an annual that grows up to 18 inches tall in full to partial sun. It blooms repeatedly from late spring to mid summer with flowers that are violet, pink, purple, white, rose and mauve. The flowers are fragrant and good for cutting. To thrive, they should be protected from from cold temperatures, root rot and mildew.
Protect the plant from root rot by watering it regularly but making sure not to overwater it. Touch the soil with your finger. If you notice it's drying out, add water. However, don't let the plant grow in standing water, or it will rot.
Keep the blooms flowering longer by pinching off dead blooms. This will encourage the plant to become bushier and last longer.
Plant the gillyflower in a protected spot to encourage the annual to over-winter (last through the winter). Look for a spot that protects the plant from heavy snow or ice buildup, such as under a roof overhang.
Buy mulch from a garden store or nursery. This includes cedar mulch, straw or hay.
Add a heavy layer of mulch to the crowns of the gillyflower in the late fall. Concentrate about four to six inches around the plants. This has been known to cause the plant to last through the cold season.
Look for powdery mildew that is a dusty white or gray coating on the leaves. It usually starts as circular white spots that become larger. Matthiola incana is susceptible to it.
Remove some of the mildew by rubbing the leaves. You also can apply a fungicide when you first notice the patches. Follow the manufacturer's instructions for application. Usually the fungicide contains sulfur, Bacillus subtilis, potassium bicarbonate, lime sulfur or neem oil.