Is it OK to use water from the dehumidifier bucket for my houseplants?

The owner’s manual for a dehumidifier says that the water is not safe for drinking, but the manual should, perhaps, include that it is a very good source of water for our houseplants. Rainwater and water from melted snow are usually our best water sources for all of our plants. The water that seems to magically appear in the bucket of the dehumidifier comes from the air—just like the rain and the snow. Sometimes it even goes through a filter before raining into the bucket. Tap water can be very hard, very soft or highly chlorinated, and when used on houseplants can cause a salt buildup that shows up as a white crust on the soil or sides of the pot. Too much salt can change the pH of the soil. Ideally, water should have a neutral pH, be room temperature and, if from the tap, be allowed to sit overnight so that chlorine can dissipate. If you are concerned that the dehumidifier water has accumulated mildew, mold or dirt while sitting in the collection bucket, clean the bucket occasionally with a 1:1 water and white vinegar solution to prevent contaminants from being transferred to your potting soil.

I have self-seeding plants in my garden that I pull out before they go to seed and spread around too abundantly. If I pull them when they are in bloom and put them on the compost pile, will they still go to seed even though the roots are exposed and the plant is dying? I don’t want to end up inadvertently spreading the seeds through the beds when I use the finished compost.

First of all, if you pull these plants when they are still in bloom, they haven’t finished the process of making the seeds. If you miss a few and don’t remove them till after the bloom has long faded, then the seeds have formed. If you maintain a hot compost pile, one that reaches a measurable 140 to 160 degrees, the heat will not only kill many pathogenic organisms, but also self-seeding plants. A hot pile works best if it is made up all at one time and then allowed to compost completely without further additions of material. You don’t say what kind of plants these are, but you might consider deadheading to “trick” the plant into blooming again. Then you can enjoy more blossom time and get the jump on the seed-making process before it begins.

As organic matter (compost, mulch, etc.) is added to the garden, how do the beds not gradually grow higher? Does the organic matter decompose to literally nothing? Or do the particles just become so small that the beds’ height is relatively unaffected?

There are two actions at work. First is that the decomposition process continues after the compost has been added to the beds. A very small percentage of the matter, called humus, is left at the end of the decomposition process. As decades go by with more and more organic matter added to the beds, the soil level would increase.

The second action at work is that plants are being grown in the beds and they consume the humus along with the other elements that comprise the soil. If more organic matter is added to the beds than is consumed by the plants, then very slowly over time the beds will gradually grow higher.

My basil is riddled with holes. I can’t find any pests hanging around the plants or on the leaves. What to do?

Basil (Ocimum basilicum) can be grown in Michigan gardens as an annual herb when the ground warms in the spring or inside year-round. Basil is grown for many purposes, including crafters using it in potpourri and dried flower arrangements. Cooks find endless culinary uses for its unique flavor, including the making of vinegars, baked goods, jellies, salads and Italian dishes. Gardeners value basil as a beneficial companion plant for many vegetables to help improve growth and flavor while providing some protection from insects. We can rub leaves on our skin and place fresh sprigs on the barbecue to repel mosquitoes or lay them on top of food bowls to stop flies from landing.

Despite all its insect repellent properties, basil itself is subject to a variety of pests, including leaf-chewing slugs, snails, Japanese beetles, rose beetles, caterpillars, thrips, white flies and flea beetles. Realizing that there are a number of pests that feed on basil, your first step will be to clearly identify which pest is causing the leaf damage before a course of action can be chosen. Slugs and their relatives hide during the day, but during the night they leave telltale slime trails to identify them after the fact. Flea beetles can hide on the undersides of the leaves, with many tiny shot holes as evidence of their presence. Most of the others are able to be observed during the day if you are vigilant.

Once identified, one or more of the solutions below will help you to successfully grow and harvest this useful, valuable herb.

• Create a healthy environment by providing your plants with full sun and ample water. Plant in a nutrient-rich, well-drained soil.
• Rotate plants and introduce beneficial insects into your garden.
• Use organic controls including insecticidal soap and oils, B.t. (Bacillus thuringiensis), plant-based insecticides (pyrethrums) and diatomaceous earth.
• Learn and practice the tenets of IPM (Integrated Pest Management).
• A few pesticides are registered for legal use on basil, but the residue left on the plant and the chance of inhalation during application can be toxic.

We have a rose of Sharon bush and it died suddenly. It is 6 to 7 years old, and showed no signs of stress. In fact, last year, it had the most beautiful blooms ever. What could we have done to prevent this? We have 2 more of these bushes, and would hate to see this happen again! They get sunlight until late afternoon, and we are on sandy soil.

Every year the onset of spring brings with it different changes to our gardens. We can expect occasional winter die back of branches on rose of Sharon (Hibiscus syriacus). With careful spring maintenance pruning to remove the dead wood, we will still enjoy a multitude of flowers that are produced on this year’s growth. While the past winter was very cold, death is seldom the result of one problem, but a combination of conditions over the life of that plant. The best defense you have is to always remember “right plant right place,” improve watering and fertilizing practices, and keep an eye out for insects and diseases that can stress a plant and leave it vulnerable to winter kill.

I have neglected trimming some juniper tams under our dining room window for several seasons. They are now over 6 feet tall. Can I cut them back nearly to the ground and expect them to regrow? They have no foliage under their outer surface growth.

Junipers will not tolerate heavy pruning because they do not have latent buds below the foliage area in older wood. If branches are pruned back to older wood with no foliage, the branch stub usually dies. This fact makes it important to choose a variety of juniper that has a growth habit and mature size that will suit the planting area you have selected. The growth habits of junipers vary from low-growing ground cover varieties to large conical-pyramidal forms. You might just want to replant the area with a more suitable juniper that will require much less maintenance pruning.

I have a bed that was installed with landscape fabric (to prevent weeds) and rocks for mulch. Can perennials in the bed still spread invasively?

Perennials that are invasive got that reputation because they go where they want and take no prisoners. The landscape fabric may challenge them for a time. But most invasive species do their dirty deed with rhizome type roots. The fabric will keep them warm, trapping moisture, allowing them to run until the root finds a weak point. To avoid this problem, plant perennials with a clumping habit rather than a running one. Avoid those that offer “quick coverage” or those that boast “self-seeds.” That seed will sprout in the crevices between your rocks, and the roots will work through the fabric. Remember that landscape fabric is a woven plastic material that allows air and water to pass through. Weeds need sunlight to germinate. The fabric effectively prevents that. The fabric may retard the individual growth of perennials planted through the holes cut in it, but it will not prevent invasive plants from following their natural habit.

I have crabapple, cherry, and mulberry trees. When is the best time to cut off low-hanging, big branches? Also, can I straighten an established tree?

Prune your crabapple in fall to early spring. This is the dormancy period when major limb removal causes the least bleeding. Mulberries are also mid-winter prune candidates. Even in full dormancy, older trees may still bleed profusely. Cherries, either sweet or sour varieties, should not be pruned in winter. They are susceptible to silver-leaf disease. Pruning must be delayed until bud-burst in spring. However, if a branch is dead, diseased or damaged, it should be removed as soon as you notice it. This holds true for the crabs and mulberry as well. If you are merely pruning for convenience or aesthetics, wait until the appropriate time.

As for straightening an established tree, you need to determine why it is crooked. Are there prevailing winds, which have caused the trunk to lean? Was it improperly staked as a sapling? Is it seeking sunlight from under the canopy of an overshadowing tree? You can open up the canopy of an adjacent tree if shade is the cause. You can also prune the canopy of your leaning tree so that it appears more in proportion to itself. There are methods for forcing branches to grow in another direction. I would consult a professional arborist before attempting this on your own.

I have grubs in my lawn and flower beds. I know how to treat my lawn but I’m not sure what to do about the flower beds.

White grubs are the larvae of various scarab (or chafer) beetles, including Japanese beetles, June, and May beetles. The larvae overwinter in the soil and pupate in early spring, with adults emerging in late spring to early summer. Michigan had a long, cool spring. This stalled the emergence of the adult beetles, which are currently devouring the landscape. The adult beetles are only susceptible to repeat insecticide applications. If you find a small infestation, hand-picking and dropping them into soapy water will suffice. However, adults are present through the entire growing season. It is important to be vigilant so adult beetles do not lay more eggs in the soil. The eggs are invulnerable. The grub larvae are susceptible to several kinds of granular insecticide sold specifically for lawn treatments for grub control. You can work this granular formulation into your flower beds as well. Remember, grubs feast on roots, which means perennials and ornamental shrubs are also on the menu, along with your lawn. As you work the soil in your flower beds, you can destroy grubs and pupas as you find them. That’s one less procreating eating machine in the landscape.

I am moving to a new house that is located on a freshwater lake. The backyard has three different levels that are built like stairs; they are large areas of land. What plants would be best suited for this environment, and which ones should I refrain from planting?

Your recognition of the impact on the lake is admirable. The sections you describe are known as bulwarks and are intended to prevent erosion of land into the lake. First and foremost, avoid the use of fertilizers and pesticides. Since they pass through the soil and are so close to the lake, they enter almost immediately. Just a couple of the effects are increased algae growth and killed fish. To avoid having to use fertilizers, stick with native plants (because they are native, they require little or no fertilizer to thrive), especially in the first three zones from the water’s edge to your lawn zone. In addition, plants (rather than lawn) will absorb fertilizer runoff before it hits the lake. If the lawn extends all the way out to the lake, remove at least 10 to 12 feet of lawn and replace it with native trees, ground cover, shrubs, ferns and wildflowers. The first few feet from the waterline needs to be water-loving plants (sedges, lady fern, etc.). The next 10 feet will require plants that prefer moist soil, but not wet. Finally, the last zone extends to the lawn. A variety of shade trees is important for this area. All of this does not mean you must create a barrier of plants that block your access or view; just try to use a combination that will allow continued viability of the lake and an enjoyable view for you.