MAY
2003

 

 

 

By
Beverly Shaw
 
Advanced
Master Gardener
Purdue University

 

 

 

 

 

05-01-03

Question and Answer

Q.  I have 6-year-old flowering dogwood trees that have never bloomed. The foliage looks healthy each year. What do you suggest? -- Carrie Ehresman, West Lafayette, Ind.

A.  It does take a dogwood a few years to become established, and we don't make the job any easier for them. Drive through Southern Indiana and notice where the dogwoods are growing. They're nestled into the edge of the woods where they receive shade and protection from larger trees above. We often plant them out in the middle of our yards, in full sun and clay soil, and expect to replicate their performance in nature. Help the tree feel more at home by removing turf from a circle around the trunk and adding a layer of mulch, at the very least.

There are many possible reasons for a lack of flowering in plants, including age, light, excess nitrogen, temperature and pruning. Make sure your plant is receiving a half day of sunlight. Fertilizers high in nitrogen, like most turf fertilizers, encourage foliar growth at the expense of flowers, so keep these away from the plant. Only prune just after flowering, or in your case, just after other dogwoods in the area flower, so you don't remove next year's buds. Finally, provide 1 inch of water per week, supplementing rainfall if necessary.

There is one more possibility. Dogwoods are often shipped into the Midwest from southern sources. These plants are not adequately hardy in northern areas. Many flowering dogwoods in the Midwest have minimal flower production, which is caused by this lack of flower bud hardiness. If possible, ask the nurseryperson or garden center where the trees are grown to save yourself disappointment three to five years down the road when the trees show limited flowering.

Q.  Each year, my perennials grow strong and healthy, then crash to the ground as the year goes on. I don't like having to tie them all up since it takes a lot of work and makes the plants look unnatural. What can I do? -- Kayla Jennings, Indianapolis, Ind.

A.  Start pinching. By pinching the growing tips in early spring, you cause the plant to branch. Branching makes the plant become shorter and stockier. In addition, all those branches get somewhat intertwined and help hold each other up.

Most gardeners know about pinching back mums but don't realize how many more plants they can pinch. Consider pinching most plants that flop, including black-eyed Susan, phlox, sedum, Boltonia and all kinds of daisies. Pinch until a month before their normal blooming time, then stop, allowing them to form buds.

Q.  I have a Wisteria vine that I planted six years ago. The vine is growing very well, but so far, no flowers. What must I do to force the bloom? -- Richard Croft, Muncie, Ind.

A.  Wisterias pass through an annoying, juvenile, non-blooming phase, and vines started from seed may require 15 years to bloom! Seven years is more likely, however. Encourage them to bloom with proper fertilization and pruning. Too much shade, water, fertilization or pruning will produce lustrous foliage at the expense of flower production. Excess nitrogen causes leafy growth, so apply a light dose of a balanced, low-analysis fertilizer, such as 6-10-4 in early summer.

Since flower buds are formed the year before bloom, it is important not to prune in late summer. Prune back vigorous shoots in early summer. Flower buds are produced on spurs that grow from the side shoots, so do not drastically prune the side shoots. Make sure the plants are in full sun, and be patient. My own wisteria finally bloomed after five years, the week I moved out of my house. I had the privilege of enjoying it for about five minutes! Still, I'll plant another in my new garden.

 

Contact: B. Rosie Lerner
Editor: Olivia Maddox,