I was preparing a bed for planting last fall and while I was turning over the soil, I kept pulling up jet black roots about 1/4 inch in diameter. They had sinewy, white centers and traveled all over the 15 by 30 foot area I was working. What are these roots? I remember some ferns popping up in this area earlier in the year.

I suspect you may be encountering the bracken fern, common throughout Michigan and the Great Lakes region. It reproduces by spores produced on the underside of the leaves and spreads by way of a thick, black and scaly rootstock that may grow to a length of 20 feet or more. Shoots can pop up almost anywhere along this rootstock. A vigorous root system, such as the one produced by this fern, can be quite invasive and can quickly spread out of control making a pest of itself. However, the roots will not survive if they are not nourished by the top growth. Continue to pull out the roots as you work the bed. Eliminate any top growth as it appears and the root system will eventually die off. Be persistent in your efforts and you will gain the upper hand.

When I fertilize certain annuals, why is there more foliage growth than flowers? I believe cosmos are one of them.

It could be what you are fertilizing with. Complete fertilizers contain three primary nutrients, listed as three numbers on the fertilizer package, such as 12-12-6. They represent the percent of nitrogen, phosphorus and potash contained in that product. These three numbers appear on all fertilizing products and are always listed in the aforementioned order. A properly balanced fertilizer, in combination with other critical growing factors such as water and sunlight, can promote growth and flowering as well as enhance vigor, general hardiness and disease resistanc

If one of these critical elements is lacking or is extremely out of balance with the other nutrients, the fertilized plant may not perform as expected. For example, if you used a lawn fertilizer with an analysis of 34-4-4 on your cosmos, the overbalance of nitrogen is likely to produce a very bushy, green plant with few flowers. A better combination of nutrients would be an evenly balanced fertilizer such as a 12-12-12 or a 20-20-20. Once the plant is well established, a fertilizer higher in phosphorus (the middle number) will generally enhance and improve the plant’s ability to produce abundant flowers. Consider using a 5-10-5 granular fertilizer or giving the plants a “punch” of water soluble fertilizer (fertilizers intended to be mixed with water and used as a watering solution) such as 10-54-10.

Can tulips be divided? If so, when and how do I do it?

The sad truth is, tulips are not a truly dependable perennial in Michigan. Our springs are often too brief, starting late and becoming summer almost overnight. If summer comes on quickly, the foliage may die down before it has time to replenish the spent food reserves. The result is a smaller bulb (than the one you originally planted) that survives to the following spring. Tulip beds in Michigan produce their best show in the spring following fall planting. Each successive year produces fewer and smaller flowers. Tulip division becomes a moot point.

Another alternative is to plant early-blooming tulips so the foliage can remain longer, thus re-energizing the bulb sufficiently. Or, you can simply treat tulips as an annual, replacing the beds with top-size bulbs the following fall. Keep in mind that other spring-flowering bulbs are more dependable perennials for our area. Daffodils (Narcissus) will return year after year, and multiply in the process.

When is it safe to put terracotta pots back outside?

It is safe to put clay pots back outside when temperatures consistently stay above freezing.

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.