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The leaves on my African violet have suddenly wilted and turned a grayish color. The plant bloomed really well in late winter for a few weeks. It is in an east window and I haven’t changed the way I have been watering it. Any ideas?

If the center leaves are wilting, it could be crown rot. Try not to get the crown (center) wet when watering. If the outer leaves are the ones giving you the problem, it could be due to the cooler temperatures during winter. Plants will not need as much water when cold. If you have not changed your watering patterns, you could be overwatering.

Should ALL the foliage on spring-flowering bulbs die back before being cut off, or can it all be cut off when the leaves are one-half brown?

A common mistake with spring-flowering bulbs is to remove the foliage prematurely. When tulips and other spring bulbs bloom, they consume, and quite often exhaust, the built-up food reserves stored in the bulb. If the bulb is to have any chance of blooming the following spring, the foliage should be encouraged by fertilizing (with something like Holland’s Bulb Booster) and left in pace until it completely dies down. Because you want to direct as much energy as possible into bulb-building, remove the flower stems when the flower petals have fallen. Allowing the spent flowers to go to seed will only further divert energy from next year’s bulb production.

Can you recommend some annuals that won’t be eaten by rabbits

If you have problems with rabbits, here a few annuals they usually stay away from: wax begonias, geraniums, canna, celosia, cleome, lantana, marigolds, portulaca, salvia, petunias, and statice.

What does “girdling” roots mean, and what are the consequences?

In general, a trunk or limb is girdled when something is tightly wrapped around it. This can be a piece of twine or wire, for example, or an actual root from the plant itself. Girdling roots choke off the flow of water and nutrients from the roots to the leaves, as well as preventing food produced in the leaves from reaching the roots.

They can also compress and weaken the trunk of a tree at or above the root collar flare (the junction between the trunk and the main roots), causing it to lean and lose its stability. Trees having girdling roots suffer a slow decline in health and a premature death.

A girdling root will also affect the appearance of the tree trunk. Usually tree trunks flare out where they enter the ground. The root will prevent the collar flare, and sometimes the trunk may get narrower and appear flattened or sunken.

Most tree roots are in the top 6 to 24 inches of soil and grow out from the trunk in a spreading manner. Cultural practices that can adversely affect this natural root pattern, and possibly cause girdling roots, include: 1) Planting in a hole that is too small so the roots cannot easily spread out, 2) planting container-grown trees that have roots growing in a circular pattern, 3) planting a bare root tree by twisting roots to fit into a small hole, and 4) leaving wire baskets, burlap and any part of a container in the planting hole.

The most common theory of the cause of girdling roots is that they develop as a result of trees being planted too deeply. When root systems are buried, less oxygen and water is available. The roots will grow up towards the surface of the soil and tend to encircle the trunk. The more deeply buried the roots are, the fewer the roots available for the tree to become established.

Symptoms of girdling roots include: 1) Leaf scorch, early fall color, early leaf drop, or damage on one or two branches, 2) abnormally small leaf size, 3) excessive twig dieback, or the appearance of large, dead, leafless branches, 4) thin appearance to the crown, or overall stunting, 5) little or no trunk taper at the collar, 6) leaning, and 7) susceptibility to environmental extremes and other problems.

The only sure way to determine if a girdling root is the cause of a problem is to examine the root system and its relationship to the tree trunk. Look for roots, ropes or wires encircling the trunk. If the trunk is abnormally flat on one side at the soil line, carefully dig below the soil line to look for a girdling root. Look for wires or ropes that were not removed at transplanting time, but which now may be girdling the trunk.

When is the best time to plant tulips, daffodils and most other bulbs in the fall?

The “window” of time for planting bulbs in fall is fairly wide. Here is a general guide to follow: Start planting bulbs once nighttime temperatures drop into the low 50’s or 40’s for two weeks. Finish planting once hard frosts are coming. Generally bulbs root best in the period six weeks or more prior to the ground freezing. After planting bulbs, water the site well. Typically fall rains will take over this task for the balance of the season. For more information on fall planting, visit www.bulb.com and go to “Bulb Basics” and then “U.S. Planting Regions.”

I have a huge bleeding heart plant that has become like a bush (5 feet wide and 4 feet tall). It is beautiful in May and June, begins to fade in July, and in August becomes a large, ugly, dead-looking hole in my perennial garden. How do I handle this mostly beautiful plant? When can I cut it back, and what should I plant near it? It is in a large (30 feet by 10 feet), sunny, and well-drained area. T.S. Hartland

Your large bleeding heart (Dicentra spectabilis) begins to fade and droop by the end of June because nature’s thermostat is rising quickly. Despising heat, Dicentra enters its dormant phase. By having it in a sunny area, you are pushing its tolerance of heat and light. That is why it melts out by the end of June. It does not hurt to cut back the dilapidated foliage to within a few inches of the ground. These showy bleeding hearts often cast seed. So you may find little sprouts appearing in late summer to early fall. Cutting back the large, fading foliage will allow light and air to feed these seedlings and you will have more plants for next season.

Since your bleeding heart has exited center stage, the object is to add plant material around it not only for camouflage, but to extend the season of color and interest into winter. As you research perennials and other plants, make a list of their bloom times and blossom colors, their plant height at maturity, and how long they hold their foliage. Layout a planting diagram that varies the height and bloom interest. You know the size of the garden bed. Use the information given about the perennials to help you lay out a pleasing pattern with enough room for their growth. Arrange tall plants to the back of the bed and shorter ones to the foreground. Be sure to consider clusters of summer-blooming bulbs and larger shrubby perennials, such as blue mist shrub (Caryopteris) and St. John’s wort (Hypericum) that add presence, but not bulk.

Ornamental grasses offer a long-term reward in the perennial garden with their graceful forms. The plumes of maiden grass (Miscanthus) and feather reed grass (Calamagrostis) really make a statement from mid-August all through the long winter months.

Consider working a small ornamental tree such as a witch hazel into your arrangement, or a small woody shrub like dwarf fothergilla. These provide fall and winter interest long after all the perennials have died back. They also provide natural “scaffolding” to a garden when snow is the only bloom around. They anchor the beauty of the perennials and give them a great backdrop.

My white pines are maturing and smothering the lawn with pine needles underneath. They were originally planted by the former owner as a privacy/sound barrier. They are beautiful but take up an ever-increasing amount of landscaping and gardening space. If I only cut off the lowest line of branches, what shrubs will adapt to all the falling pine needles and shade to keep our vision and sound of the road behind us to a minimum? Anything that flowers or has good fall color would be a bonus. J.S., Novi

White pines shed needles just like deciduous trees shed leaves. And as the pine tree grows, the once dominant lawn begins to shrink and decline. Lawn turf needs sun and water to thrive, neither of which it will get under an ever-expanding pine. So don’t try to resuscitate any lawn under the canopy. If the trees have not become misshapen as they’ve grown together, it might be feasible to remove one or two to allow the others to complete the job of filling in. There is a plus to those pine needles. They make great winter protection not only for the pine tree, but also for other perennials and plants in your landscape. Use some of the abundance as mulch and acidifying compost around plants in other garden beds.

Understand that the best noise barrier and privacy fence you have is leaving the pines alone. Perhaps a focal point bed placed several feet in front of the pines and bermed a couple feet above the plane of the lawn may offer you that colorful relief. The pines would serve as a great green backdrop to a mix of seasonal flowering shrubs and perennials that you could enjoy all year without jeopardizing your natural screen.

If you still want to remove the lower line of branches, remember you are dealing with very dry shade and low light. Anything you plant must be out past the drip line of the pine tree by several feet in order to maximize its sun and water exposure. Be aware that even removing the bottom row of branches will not prevent the expansion of the pine tree canopy and width. Whatever you plant may have to be moved as the pine trees continue to grow. To maintain minimum road noise and privacy year-round, you might try a contrasting low-growing evergreen. One such drought-tolerant shrub is the juniper ‘Gold Star’ with yellow needles. You can intermix perennials such as variegated-leaved hostas to lend brightness to the shade. There are a number of perennials available today that would suit your conditions. However, most do not have four-season presence and will not replace the screening of the pine tree branches.

I planted a small tree in early June and animals began chewing on the bark in late June. I know that tree wrap is normally used in the winter, but is it safe to use it in the summer? I don’t want to cause disease problems on the bark.

Rather than using paper tree wrap, try the plastic coiled wrap that is flexible and perforated to allow air circulation. It comes in assorted diameters as well, so you can custom fit it to the current caliper of your tree and allow room for growth. Reputable nursery and garden supply centers carry this product. Nursery stock trees will often already have this flexible coil around the trunk. You only need it about two feet up from the base, which is about the height a rabbit can stretch.

Young deer will sometimes sample bark to see if it’s tasty. But they really prefer new leaf and flower buds. If you have evidence of deer, such as droppings or hoof prints, you may have to resort to spray products such as Deer Off. It is a citrus and peppermint-based spray, which lasts about two to three months. It does not wash off in rain or irrigation cycles. It clings without deforming or adulterating the plant by using vegetable oil as its agent. Deer have much better noses than we do, and they find the peppermint scent and taste unpalatable.

Meadow mice (voles) and rabbits, however, are generally the culprits for chewed bark. Occasionally juvenile groundhogs will also sample young tree bark. (A bit like human babies putting everything in their mouth to get the taste and texture.) Young trees are more succulent and desirable as creatures forage for food for themselves and their broods.

If there are raised tunnels in the vicinity of your tree, then more likely you are dealing with voles. Place three or four simple plastic snap mousetraps baited with a dab of peanut butter around the base of the tree. Check the traps each morning for a week. If the traps are sprung, remove any remains and re-bait them. If done consistently, you may eliminate the entire offending colony within that period. The perforated plastic tree wrap will also deter the rabbits and frustrate the groundhogs. Using both methods should protect your tree from additional damage.

I have a couple large patches of mushrooms coming up in my lawn and in bark mulch I put down last fall. Should I dig them out? Should I do anything else to make sure that they do not grow back? Or should I just leave them alone to die on their own?

The sudden appearance of mushrooms in our lawns always sets our blood racing. What caused these “alien life forms” to appear overnight? In reality, mushrooms are just the fruits of a fungus caused by rotting wood in the soil that may have come from past construction or old tree roots and stumps.

Since you are seeing them in bark mulch you applied, the fungus spores were probably in the mulch and while still dormant, hitched a ride into your yard. This doesn’t condemn your mulch source nor do you need to remove the existing mulch and put down fresh. Mushrooms do not harm the grass or the mulch.

They should, however, be hand-picked or raked out to prevent the fruiting bodies from producing more spores and increasing their numbers. If you mow over them, you may carry spores to other parts of your lawn on your mower blades. There is no chemical that will prevent them.

Since a fungus prefers moist, shady conditions, you may want to check how often you water your lawn and the amount of air circulating in that area. Removing the mushrooms present and monitoring your maintenance methods should decrease their colonization.