Old fashioned weigela (Weigela florida), often simply called weigela, is valuable in the landscape as a specimen plant or in mixed landscape beds. The species variety grows 6 to 8 feet tall, and has pink flowers and green leaves. Over 170 cultivars are available, offering different colors and mature sizes. The dwarf "Minuet" (Weigela florida "Minuet") grows only 30 inches tall, with red flowers and green leaves tipped in purple. Wine and Roses weigela (Weigela florida "'Alexandra") grows 4 to 5 feet tall and pairs burgundy leaves with rose-pink flowers. Old fashioned weigela and its cultivars are hardy in U.S. Department of Agriculture plant hardiness zones 5 through 8.
Weigela grows best when planted in full-sun locations. It is quite adaptable, though, and will grow in part shade as well, though the plants will not flower as much as when planted in sun. Shaded plants also develop a more scraggly, open form than plants grown in sunny locations.
Well-drained soil is best for growing weigela plants. That said, weigela is not picky about soil conditions and the plants tolerate sandy, loam or clay soils. They prefer soils that stay moist, but will also grow in soil that dries out occasionally. Weigela grows best in soil with a pH between 3.7 and 7.0.
Weigela rarely requires fertilization. In fact, over fertilizing is more dangerous than not fertilizing at all. As long as the plant continues to experience healthy growth and bloom, there is no need to worry about fertilizing. If you do notice reduced growth and smaller or off-color leaves, plan to fertilizer next year in the spring. Time fertilizer applications after the last frost date in your area, but before plants start growing rapidly.
When weigela needs fertilizer, use a fertilizer that contains only nitrogen. Spread 1 to 3 pounds actual nitrogen evenly across the ground for each 1,000 square feet of planted space. Different fertilizers contain different percentages of nitrogen. Ammonium nitrate, for example, contains 34 percent nitrogen by weight. You'll need to use 34 pounds of ammonium nitrate to supply 1 pound actual nitrogen. For treating 10 square feet around a weigela bush, you'd use about 1/3 pound of ammonium nitrate. After applying the fertilizer, water plants to wash the leaves off and work the fertilizer into the soil.
Weigela is prone to winter die-back, which typically kills a few of the older canes each year. The plants have a moderate to fast growth rate and can quickly become large and scraggly, though growth rate in inches per year varies by cultivar. For both these reasons, weigela requires yearly pruning. Before pruning and in-between pruning different plants, disinfect pruning tools by soaking them in a mixture of 1 part bleach to 3 parts water for 5 minutes. Rinse the tools in cold water and allow to air-dry before use.
Prune out any dead wood in the late winter. For mature weigela plants, you can remove some of the largest, oldest stems at the same time. This encourages heavy flowering and vigorous new growth. You can also prune lightly after the plants flower to maintain an attractive shape. Weigela cultivars flower in mid to late spring, so you'll be doing this light pruning in the late spring. A few flowers may also appear during the summer.
Pests and Diseases
Aside from their need for pruning, weigela are low-maintenance plants that are rarely troubled by pests or diseases. Occasionally, they may suffer from gray mold or wood rots.
Gray mold, caused by Botrytis cinerea and other species, appears as a blight that infects dead and weakened plant material. It causes browning on the leaves and flowers. You can prevent gray mold by planting weigela in its ideal growing conditions, and avoiding overhead watering. The best way to control gray mold is to remove and destroy infected plant material. Burning is the recommended disposal method, but in locations where you cannot burn, bury the infected clippings under at least 12 inches of soil. Disinfect pruning tools after use on an infected plant.
Wood rot fungus only breaks down plant material that is already dead. It may occur on dead or dying weigela plants, or around the base of the plant if the ground is littered with decaying twigs and leaves. Wood rots can look like shelf fungus and mushrooms, or appear as a fuzzy growth. If the plant is still growing, you can remove the fungal growth and clean-up dead material around the plant. There is no cure if the weigela plant itself has already started to die and rot, so it is best to remove the plant. Since wood rot cannot spread to living tissue it does not endanger healthy plants, and you can dispose of the removed bush however you like.