Bad hair day

What can I do to restore the shape of my spiral junipers? They were just beautiful for two years and then they grew a shock of straight-up foliage that makes them look terrible. Small stems are also beginning to grow straight up from the lower limbs. Please help. H.F., Country Club Hills

Evergreens that have been trained into unnatural shapes such as spirals, topiaries and standards are high maintenance plants. In order to keep them looking formal, you must continue whatever treatment was given them to arrive at the formal shape to begin with. In the case of your spiral junipers, they were probably wired around a support to train the main stem, clipped to obtain the swirl of foliage and then sheared periodically to maintain the smooth shape.

You have several options at this point. You can shear off any unwanted new growth and attempt to keep the plant looking the way you want it to for a few more years. Eventually it will begin to decline from this treatment. You can replace the plants when this happens. You may also hire a professional gardener to maintain the shape of the plants. Or you may let the plants revert back to their natural shape, that of a narrow orb with upright branches. Like any big ‘hairstyle’ change, there will be an unattractive transition period if you choose this last option.

Poor bedfellows

I love my ornamental grasses but I think they are killing my nearby evergreens. I am noticing that the needles on the side near the maiden grasses are turning brown and leaving my dwarf spruces and mugho pines looking as though they are dead. Are they toxic or is it from the grasses using too much water? D. P., Kankakee

Although grass plants do possess certain allelopathic qualities that inhibit the growth of young woody plants (that’s how the prairie remains a grassland and it is a quality shared by many plants that grow in large stands), it is not strong enough to harm your evergreens. What is most likely happening is that the Miscanthus sinensis ‘gracillimus’ (maiden grass) is becoming large enough to block sunlight from reaching the evergreens. Depriving sunlight will certainly cause dieback on the effected side of the plant. You must move one or the other to remedy the problem. Ornamental grasses are best used with herbaceous perennials or large natural groupings of woody plants.

Slime mold

Last summer I noticed patches of a vile looking substance on my wood mulch. It resembled dried mustard and when I tried to hose it away a cloud of purple smoke filled the air. What was it and how did it get there? J.S.C., Warsaw, Indiana

The substance was a slime mold; not really a mold and not really a fungus, but they share traits of both. This particular slime mold grows on decaying wood where it eats the carbon and grows, moving closer to sunlight as it does so. They are perfectly harmless, but the cloud of spores you released into the air when you hit it with the hose may irritate the lungs, especially if you suffer from asthma or allergies to mold. It’s best to allow the slime mold to dry up and disappear on its own. You can gently break up the surface to get it to dry out more quickly.

Outgrown its space

I bought a dwarf weeping pine about 10 years ago and it has now become too large for the space where it is growing. Can I move it? Also, why is it called a dwarf when it is now 15 feet tall? I feel like I was misled. C.G., Palos Hills

Dwarf plants are obtained from vegetative cuttings of individual plants that have grown much smaller and more compact than they typically would. Perhaps a nurseryman has found a spruce that is unusually small, or a witches broom (tight congested growth in a tree), as was the case with bird’s nest spruce. These smaller plants are produced from cuttings of the original and sold as dwarf plants. Your dwarf weeping pine is probably a cultivar of white pine. When you consider the ultimate height of a standard white pine, 15 feet would easily qualify as a dwarf form. You can’t assume that all dwarf plants will remain smaller than we are. Some may reach heights of 20 or 30 feet. The eventual size is usually reported on the plant label or available online.

You may want to move the plant. I would do so only with the help of a trained professional, and even then it will be a dicey proposition. You could also remove smaller branches and thin the tree into a lighter, more transparent profile to keep it in the space where it is currently growing. Look inside the draping foliage and follow the main trunk; picturing the tree with all growth removed except for scaffold (main) branches. This will help you determine whether or not to attempt reshaping the plant.

Edible ornamentals?

I planted some decorative kale, sweet potato and red pepper plants. The pepper plants had variegated leaves and little red hot peppers hanging from the stems. These plants said for decorative use only, not for consumption. My question is, what about the annual sweet potato plants? I was under the impression that that was only the name for the plant and that it was not really a sweet potato plant. When I pulled them out of the containers for the winter, it looked like there were baby sweet potatoes attached to the root system. If they were baby sweet potatoes, and I had left these grow longer, would they have been considered edible? R.S., South Holland

All three plants are actually edible, but you probably wouldn’t want to eat the peppers. There are many ornamental peppers available for container planting, most with green, red or dark purple fruits. These are very hot peppers and should only be consumed by people who have experience in cooking with them. The kale, as you noted, is sold as an ornamental, and is only edible when grown in cool weather and without pesticides. It would be bitter after a hot summer in a container. The sweet potato vines are in fact regular sweet potatoes but not the best choice for tuber production. Although some people have reported one-pound tubers, the flesh is fairly woody and lacks flavor. They are also difficult to store and to use to start new plants. They either dry out or rot easily. If you would like to try growing sweet potatoes, try a variety such as ‘Vardaman’s’ or ‘Puerto Rican’ and grow them in loose soil in a large tub. Begin with 6 inches of soil and keep adding 6 inches as the plants grow. Harvest after the first frost but before a hard freeze.

Fruiting quince

I have a large flowering quince that produced a hard yellow fruit down near the middle of the plant. I picked it before it froze, but when I cut it open it still didn’t look ripe. Is quince fruit good for anything? E. K., Lowell, Indiana

The quince that we grow in our area is a relative of, but different from, the quince plants that are grown to produce fruit. Our quince, one of three species and many cultivars of chaenomeles, is more a decorative plant. Fruit does form occasionally and is usually down among the lower branches because it will only grow on old wood. Since flowering quince becomes such a large rambling plant, gardeners tend to prune them back often, sacrificing flowers and fruit. A flowering quince that is given plenty of room and left to grow naturally will form a 12-foot circle of branches that fountain out from the center.

The fruits, when they occur, should be left to soften by a light frost or two. They will be less astringent then and more pleasing to the palate. You will probably never harvest enough fruit to do much with, but they do contain loads of pectin so they can be used with other fruits in jam and jelly making.