Growth Problems for a Purple Lilac

With those delightfully scented pale purple flowers, purple lilac (Syringa spp.) provides a welcome bit of color to the spring season landscape. Lilacs grow in U.S. Department of Agriculture plant hardiness zones 3 through 5. With some varieties, this pleasure is two-fold as the trees will blossom a second time during the growing season. Purple lilacs are susceptible to a range of pests and diseases that, as well as poor growing conditions, can lead to poor development among other problems.

Waterlogged soil is dangerous and damaging for purple lilacs. Well-draining soil is preferred by purple lilac, and soil that is too wet can lead to a drowned lilac plant. To prevent this situation, plant lilacs in well-aerated soil that has good structure and is unlikely to become waterlogged. Add in peat moss and compost to improve soil structure prior to planting, as afterwards, there is little to be done, and transplanting an established lilac plant is difficult.

Excess nitrogen in the soil will lead to abundant foliage growth, but poor bud and flower production from the lilac plant. Test your soil prior to planting to ensure that there is an adequate balance of nutrients available, and amend the soil as needed. Add compost prior to planting, mixing in a 3 inch deep layer of compost to provide sustained nutrition if necessary. Over the growing season, compost tea or side dressings of compost or fertilizer can be used if required.

Lilacs grow best in full sun, and without adequate sunlight, the plants may exhibit poor growth and few, if any, blossoms will develop. While certain varieties are more shade tolerant than others, full sun will lead to vigorous and hearty growth. Plant your lilac in an area where it will receive plenty of direct sunlight, and where there is little danger of shade from larger tree canopies or buildings.

Diseases that can affect purple lilac include powdery mildew, verticillium wilt, blights and leaf spot. These diseases often cause foliage to discolor, and in extreme cases, will lead to death. However, in general, these diseases do not lead to poor growth, as death is more common. Insects that will affect the purple lilac include weevils, lilac leafminers and lilac borers. Again, these pests will cause foliage to discolor, but will rarely cause stunted growth.