Some of the blossoms on my tomato plants are disappearing. The plants are too tall to be affected by rodents and there are no signs of insects. Could the blossoms just be dropping off? Any ideas or recommendations?

Your observations and process of elimination are very good. Tomato blossoms can fall off prematurely when it is very cool or very hot, or the soil is dry. Michigan’s summer so far has been unseasonably cool, but with plenty of moisture.

Your solution is to improve growing conditions by “turning up the heat.” When temperatures continue to be cool, mulch with black plastic to warm up the soil. You can pair that with wrapping clear plastic on stakes around the plant to form a mini-greenhouse. Keep water consistent, watering when the soil is dry 1 to 2 inches beneath the surface.

We were given a hydrangea plant at the end of April. It bloomed beautifully for 1 to 2 months inside. I cut it back when all the blooms were spent. Then I put it outside and the green leaves just grew and grew, but I don’t see any new blooms coming on. Do you think it will bloom again this season? What should I do with it once frost comes?

Generally, “gift” hydrangeas are the stunning pink or blue-blossomed bigleaf hydrangea (Hydrangea macrophylla). These are often kept as houseplants in Michigan because they are not hardy to our zone 5. As container plants, they can be transplanted into the ground in zones 6 to 9, but only if they are well-sited in moist, well-drained soil heavily amended with peat moss and leaf mold. Protected partial shade is also very important.

Not only are hydrangeas particular about location and conditions, each species is picky about pruning. Cutting it back after the blooms were spent is appropriate for bigleaf hydrangea. The plant produces flowers from buds formed on the previous season’s growth. It does not typically bloom again this season. However, as you’ve experienced, you will get additional greenery.

Since this is more of a houseplant, you should bring it indoors for protection before temperatures drop and frost is possible. Be careful about placing the plant too close to heat or air conditioning vents, or windows with direct sun. As a container plant, you will need to keep the soil acidic through the use of water-soluble fertilizers, in addition to maintaining an appropriate soil medium. If you wish to encourage one color or the other for next year, you will need to check the pH of the soil on a regular basis. A pH of 5.0 to 5.5 will satisfactorily produce blue flowers while a pH of 6.0 to 6.5 will cause pink coloration.

I have a bad-looking maple tree in my backyard. There has been a considerable amount of leaves falling to the ground. Some of the leaves have burnt brown areas. We have another maple 100 feet away and it is fine. Both maples are about 15 years old. What might be wrong?

The causes are fungal and bacterial diseases. Tar spot and petiole borer flourish in wet weather. Tar spot started in the spring with a tiny infection the size of a pinpoint that spread into a yellow spot as summer progressed. Although unsightly, it is a harmless, nuisance disease. Similarly, petiole borers won’t do any real damage to the tree, but the tiny insects that bore into and weaken the leaves make their presence known by the cosmetic changes to the leaves. Spraying will not help because the petiole borers are now inside the tree and impervious to surface applications.

It is advised that leaves be raked up and removed as often as possible and not run over with mulching lawn mowers. Allowing the leaves to remain under the trees and mowing over them can cause microbes to spread and the disease can return next year. Diseased debris can be burned, if local ordinances permit burning, or composted in a compost pile where internal temperatures reach 130 degrees. Trees should not be fertilized after August 1 because that encourages new growth that will be tender and vulnerable to colder temperatures.