Q. I have some 'Green Mountain' boxwood. They had a lovely pyramidal shape when I purchased them two years ago. Now they have spiky growth at the tops, and I am not sure when to prune them. Also, I have replaced two of them and another is starting to yellow out. I do not see any insects. Can you tell me what is wrong?

A. 'Green Mountain' boxwood (Buxus) naturally has a pyramidal growth habit. You can prune out those spiky growths any time they appear. Because it sounds as if you have more than a few spikes, this is a good time to prune them, while they are dormant.

Many people shear boxwood into a more formal shape with hedge shears. Simply follow the shrub's natural growth habit with the shears until you have renewed its tight pyramidal form. If you prefer a more natural shape, one that follows the shrub¹s pyramidal growth habit but without the rigid line that shearing creates, prune the spiky growth with hand pruners. Remove the outsized stems to their point of origin on a branch or the trunk.

All boxwoods require well-drained soil. The yellowing, decline and death of some of your boxwoods are classic symptoms of poor drainage. Choosing the proper location -- one with good drainage to start with -- and careful attention to soil preparation are very important. We tend to have heavy clay soil that does not drain well.

To check soil drainage, dig a hole 12 inches deep. Fill it with water and allow it to drain completely. Refill the hole, and measure the depth of the water with a ruler. Wait 15 minutes and measure it again. Multiply the result by four to calculate how much water drains in an hour. If it drains 4 to 6 inches per hour, the site should be fine for the boxwoods. Less than an inch per hour indicates poor drainage, and you will have to find a way to drain excess water from the site or find another location.

If you're planting on a slope, do not assume the area drains well because it slopes. The surface water probably drains well, but there can be pockets of clay that interfere with internal drainage.

Q. What causes the leaves of my peonies to develop black spots and what can I do about this problem? When I cut back the bushes in the fall I get rid of the branches. I do not compost them.

A. The black spots on the leaves sound like typical gray mold symptoms. This fungal disease is quite common on peonies, especially if we have cool, wet weather in early spring as they are poking up out of the ground. Gray mold is also known as botrytis, and it can spoil the flowers, too. Peonies infested with botrytis can have numerous flower buds that turn black and shrivel up before they get a chance to open. Those that do open may be brown and mushy inside and not last very long. The dead flower petals are frequently covered with brownish-gray fuzz, which are the spores that spread the disease.

Botrytis is spread by wind, splashing rain or irrigation water, and on tools or even your hands when you work on infected plants. The fungus survives on plant debris and can persist in the soil for many years.

Remove and dispose of all the decaying and infected plant parts. You are wise not to compost the diseased plant material. Clean up plant debris around your peonies during the growing season and again before putting the garden to bed in the fall. Cut herbaceous peonies to the ground and dispose of the cuttings when the tops have been killed back by frost.

While you cannot keep them dry when it rains, avoid wetting the foliage when you water your peonies. Use soaker hoses or drip irrigation if possible. If not, use a watering wand and aim it at the soil under the peonies, rather than over the top of them. It is helpful if they have full sun and good air circulation because that allows the foliage to dry quickly after rain or heavy dew.

You can make also make fungicide applications as they begin to grow in the spring. Mancozeb (Dithane) and Cleary's 3336 (thiophanate-methyl) are labeled to control botrytis on peonies. Fungicide applications work best when applied preventatively before you start to see leaf spots. Follow label directions regarding application rate and intervals between applications.