We recently installed a rock pathway and want to fill the spaces between the stones with “step-able” plants that are low-growing and hardy. We planted some creeping thyme in the sunnier areas. I have seen Corsican mint used for this purpose in shady areas. Do you think it would do alright in southeastern Michigan?

Corsican mint (Mentha requienii) would definitely work and look nice for a very low growing (1/2 to 4 inch tall) ground cover between paving stones. The plant needs partial shade, and rich, moist soil that is well drained. It will not take drought because it is very shallow rooted. When stepped on (it will take foot traffic), it gives off a peppermint fragrance. It has small, light purple flowers in late spring and early summer. It is rated for zones 6 to 9, but many growers say it comes back in zone 5 (southeast lower Michigan). Remember it is a mint and will spread, but it is much better behaved than its relatives. It basically stays in its own area and can be controlled by removing the outside edges that have spread too far.

Cost aside, is there any benefit to occasionally adding natural mineral water when watering houseplants or outdoor container plants? I recall that gardeners in Europe do so because it mimics rainwater. I have also heard pros and cons on using distilled water, such as from a dehumidifier, for potted plants.

The best type of water for houseplants is rainwater or melted snow. Distilled water can be used but you may be deterred by the cost and work carrying the jugs into the house. Tap water (well or city) is generally suited for most plants. The water should stand overnight in a container to allow it to lose some of the chlorine. Also, it is best if the water is at room temperature. Both hard and soft water can be harmful to your plants as they can contribute to a build-up of excessive salts in the soil. Hard water contains salts of calcium, magnesium and iron. Plants use these salts in very small quantities but, in large amounts, they become toxic. Softened water is even less favorable because the softening process exchanges calcium salts that have no use. In short, save your money and collect that rain or snow – it’s free.

I have noticed that some crabapple trees have suckers and some don’t. I’m guessing that certain types are more likely to have them than others. I’m talking about the shoots of growth that come from the base of the trunk and sometimes come from the roots out away from the trunk. I have been told that there is nothing that can be done to prevent these suckers and the only thing that you can do is cut them off. I have also heard that cutting them only promotes more growth and they should be torn off. I have a great-looking crabapple, but it grows many suckers and some of their bases have become so thick over the years that they are difficult to cut and impossible to tear off. The reason I’m asking is because this tree needs to be removed from its current location. I hate to just cut it down, but it seems like there are always suckers that need to be removed. If I have it moved to another location, is there anything that can be done to prevent or reduce the number of suckers?

You might not realize that flowering crabapple trees are nearly all self-sterile. One way they are propagated is through grafting soft “whip” to a winter-hardy rootstock. Those rootstocks are what cause the suckers. Older rootstock selections were bred primarily to withstand Michigan winters. Hardiness was of prime importance to the fruit grower.

However, over the last 40 years, there have been substantial improvements in rootstocks that not only produce good root systems and are easy to transplant, but are relatively sucker-free. These are the Malling rootstocks, developed in England, and are used extensively by nursery growers today. Your crabapple may pre-date the use of the Malling series.

Another factor is how heavy your crabapple has been pruned over the years to maintain its pleasing appearance. A rootstock more prone to producing suckers will respond to hard pruning with a veritable army of soldier-like sprouts. The plant’s response is to send up as many opportunities as it can to regain leaves which produce its food. This response could be accentuated if the hard prune was done in early spring instead of late winter when the plant would be at its dormant best. Actually, stimulating root suckers, or “stooling,” is one of the ways new multiple rootstock plants are created.

It appears the heritage of your rootstock is the primary source of the problem, and unfortunately, you cannot change that. Since the tree must be moved from its current location, it might be better to remove it completely and replace it with one of the newer cultivars developed on one of the improved Malling rootstocks. If you are especially fond of this tree, you could also have a certified arborist, knowledgeable about grafting, take a softwood cutting and graft it to an improved rootstock that will not produce a sucker response to every pruning. (There are also products currently available on the market containing growth hormones which can be used to help control sprout and sucker growth on woody ornamentals.)

However, if you choose to replace the tree with a variety similar in height, blossom color and fruit, seek out a reputable nursery and specifically ask about the rootstock they use. With the tremendous number of cultivars available, there will certainly be a crabapple that mimics the look of your old one, but with none of its aggravating attributes.

Please provide advice on the riddance or control of creeping bent grass.

Creeping bent grass (Agrostis palustris), possibly your bête noire unless you tend a golf course putting green, is an invasive perennial grass. Thin, flat, and rough edged, this creeping native plant spreads through coveted bluegrass lawns by stolons (creeping stems) and by seeds. Small circular green patches in your lawn are the first signs of this invasive problem. As the stolons weave larger, more numerous, and denser verdant mats in your lawn, fewer bent grass roots grow in the soil. Thirsty for moisture during long hot summers, the green patches die and turn brown. Seeds from bent grass’ lily-of-the-valley-like seed heads scatter through the lawn every time it’s mowed. High humidity from frequent watering traps the seeds between bluegrass blades, keeping the seeds alive until they root and form new patches.

Ridding your lawn of bent grass takes time and patience. Small patches of creeping bent grass can be pulled or dug, taking care to grab as many of the roots and stolons as possible. This process should be repeated weekly or biweekly, otherwise remaining roots may sprout and cause further problems. Don’t put bent grass in your compost pile until it has first dried in the sun.

Spot treating with glyphosate (Roundup), a non-selective herbicide, can also control actively growing bent grass. Areas treated with glyphosate may be re-seeded seven days after you’ve applied the chemical. Remember, though, glyphosate will kill or damage all green plants it touches, including desirable lawn grasses and garden plants. (Herbicides that differentiate between types of grasses are not currently available to homeowners.)

Could you suggest some houseplants that are small enough to set and grow on a windowsill?

There are many, many plants small enough to grow on a windowsill. Here are a few suggestions. Cacti and succulents not only grow very slowly, but are very compact and easy to grow. They are also one of the most interesting-looking group of plants. In the flowering plant category, you could try the ever popular African violet or maybe something a little different such as a kalanchoe or miniature cyclamen. If you like trailing plants, try English ivy. Ivy grows quickly, but is easy to prune and keep at a manageable size.

A vining weed climbed all through a couple tall roses bushes of mine before I was aware of it. It will be nearly impossible to untangle the weed from the rose canes and if I try, it will break off many stems. Is it OK to just trace the vines to their roots and pull out the roots, while leaving the vines to die on the rose canes? Will that cause any harm to the roses?

You are correct in cutting the vine at the root system. Just leave the vine on your rose bush until it has dried. Then through the normal pruning of your roses, most of the dead vine will come out. The speed at which the vine grew hints at it being an annual, which would have died out over the winter.

Every so often when I dig up perennials to move or divide them, I notice that some of the finely shredded pine bark that I have used to amend the soil has a white, powdery coating on it. What is it? Is it a problem?

The white powdery coating that you describe is just nature taking its course. The shredded pine bark that you use is just decomposing, and the white is a natural fungus helping the process. This will not cause any problems for you in your garden. In fact, since you have mentioned that you are adding organic matter to your soil and periodically dividing your perennials, that seems to indicate that you have a healthy growing garden.

Last fall (September and October), I noticed healthy specimens of pear, apple and crabapple blooming. The only times I have seen such plants blooming outside of their normal seasonal patterns are when they are acutely distressed. What would have caused such a strange blooming cycle on otherwise healthy plants?

While most trees only bloom during their normal seasonal time, healthy mature trees do have the ability to set a flower bud early, known as the king flower bud. When the king flower bud has a nice, sunny fall day it will bloom. The secondary flower buds will bloom only after they have gone through their normal winter rest period.

I planted sweet potato vines in containers last summer (both the chartreuse and dark purple ones). When I took out the plants for the winter, they had grown banana-sized tubers. Could I have over-wintered these and planted them in the spring? If so, how would I do it.

Believe it or not the sweet potato vine tubers are actually edible. The taste is a cross between a regular potato and sweet potato! This beautiful vine has grown quickly in popularity for its fast growing habit and lush foliage. Yes, you can store the tubers for next spring’s planting. In the fall simply remove all foliage from the tuber, wash off any soil and let the tuber dry thoroughly for about 24 hours. After it dries, store the tuber in dry peat moss and keep in a dark area that maintains a steady temperature between 50 and 60 degrees. Next spring, remove the tuber from the peat and cut it into smaller pieces or plant whole in fresh potting soil and start watering. Place in a sunny area and in no time at all you will have lush green or purple growth!