What is the cause for maple tree leaf veins to be much darker than the leaf itself?

What you are describing is symptomatic of leaf chlorosis. Chlorosis is the general yellowing of a leaf that can be brought on by a variety of factors. Disease, insects, cold weather, pollutants, a high level of minerals, or nutrient deficiencies can cause it. Your best course of action is to conduct a soil test. Call your county MSU extension office and they will help you obtain a kit complete with easy instructions. The results will help confirm or rule out problems in the soil. The test will also check the pH level in your soil. The correct pH level enables your plants to take up needed minerals and nutrients that are available in the soil. Read your test results carefully and if you need any clarification of the information, the extension office will again be glad to assist you.

Do cosmos reseed themselves? Do I take off the spent blooms or leave them to dry and fall off?

Most cosmos reseed themselves but not always reliably or true to the variety. The common cosmos in Michigan is an annual, so the best way to have nice plants that are the color and height you want is to sow new seeds each spring when the ground has warmed to 70 to 80 degrees. Or you can purchase plants from local garden centers. Plant them in full sun in the back of the garden where a fence or other plants can hold them up. They tend to flop in wind or heavy rain, and it is difficult to stake them because of their thin stems. In her book Annuals for Michigan, Nancy Szerlag suggests placing twigs around the young plants for support that will be covered when the plant is older. The plants germinate easily in the garden with only 1/8 inch of soil covering them. They are very drought tolerant and don’t need much, if any, fertilizer for the whole growing season.

To keep the plants blooming throughout the summer it is best to remove spent blooms. It also makes the plant look neater. If they get too tall and blooms are weak you can trim them back to half their height. They will grow back bushier to bloom again later in the summer. You can selectively cut them back, so there are still some blooming while the others grow back. If you want to encourage reseeding (and that means anywhere in the garden with help from the wind and critters), leave the seed heads on in the fall. The finches and other small birds love the seeds, and what they don’t eat may reseed.

How do you go about looking for a good landscape company? We are planning on having some bushes planted next spring and need some landscape advice.

There are basic rules to keep in mind. Define exactly what you want the contractor to do and where. Make a list to organize your ideas and even a thumbnail sketch. Ask yourself how involved you will be with the installation and maintenance. Do you want to observe from the sidelines, or get in there and dig? Will you handle the annual maintenance of your new landscaping, or pay for that service? A single contractor who offers both installation and maintenance has greater continuity with your property than two separate companies. Know your budget and prioritize the areas you want planted. You may decide to do your plantings in phases. Once you determine these conditions, make a list of contractors that fit them. Two excellent sources are the Michigan Green Industry Association and the Michigan Nursery and Landscape Association. These professional trade organizations will have lists of companies who fit your criteria. Also ask friends and neighbors whose yards you admire how they accomplished it. You can learn a lot about the working relationship between contractor and homeowner that way. Then start calling. Be patient as most good contractors are very busy. Get at least three bids or plans, and get them in writing, with details about timetables, unforeseen changes, site repair from heavy equipment, etc. Ask them for references of completed projects and follow up on them. The more informed you are as a homeowner about the work you want done, the happier you will be with the end result.

We lost a beautiful, and formerly healthy, horn beam tree this spring. It did not shed its leaves last winter which it did normally. We still have not removed it as of mid-July; is there any chance it will come back? If not, what are the possible causes of its death?

This year we are seeing a lot of winter injury all around Michigan as a result of several events last winter. The warmer than usual fall, where trees were slow to lose their leaves, was followed by a cold snap (0 to -15) in early December. This sudden freeze killed a lot of young and/or (drought) stressed trees. Winter injury in Michigan is a common occurrence. Most winter injury is caused by cold snaps early or late in the dormant season or mid-winter thaws followed quickly by cold temperatures. When plants become cold acclimated in the fall, the cold hardiness begins at the shoot tips and progresses down the tree to the trunk and finally to the ground. Injury to the base of a tree often indicates that the injury took place early in the season, as the plant was hardening off for winter. Based on your description, the tree should be removed. If your tree survived, it would certainly have shown some sign of new growth by July.

Is there any way to sterilize poplar trees so that they don’t produce those awful sticky pods or the white floating fuzzies? This was the worst year and clean up takes forever.

No, there isn’t. The best recommendation is to remove the tree and start over. The Eastern cottonwood (Populus deltoides) has little residential landscape value due to its messy habits and weed-like seedlings. Its soft, weak wood easily splits and breaks in storms. There are several cottonless (male) varieties available. But with the abundance of so many preferred tree species for homeowner use, it seems pointless to replant with a male version of an essentially scrap tree. If you remove your offensive tenant, consider the maple family for replacements. Avoid the quick-growing, overused silver maple that rivals the cottonwood in susceptibility to insect pests, diseases and weak wood. Also consider the European beech (Fagus sylvatica), which has many excellent cultivars available.

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.

Mulching is a good practice in flower beds. Should I also mulch my vegetable garden? If so, is it appropriate to use the same mulch as I use in my flower beds? What is this I hear about using colored plastic for mulch?

Mulching your vegetables is good for the same reasons. It reduces the loss of moisture during hot periods, keeps plant roots cool, and reduces the number of weeds that can grow to compete for soil nutrients. Know your vegetables because some will thrive in dense conditions. They will naturally crowd out the weeds. Organic mulches such as ground leaves, straw, pine needles, and grass clippings also add food for soil-dwelling organisms and eventually decompose into soil themselves. Avoid more than a couple inches of mulch around your vegetables. Overmulching can absorb the water, retard soil warmth, and even change the pH and nutrient content of your soil.

As for the colored plastics advertised, be sure to understand what the product is made for. Most often seen is black plastic. It is cheap, provides good weed control, and warms the soil. However, it does prevent water from penetrating. IRT (Infrared Transmitting) plastic provides good weed control since it blocks the visible light that weeds need for growth. However it costs more than the traditional black and still acts as a water barrier. SRM (Selective Reflective Mulch) is the red plastic marketed. It offers poor weed control and prevents water penetration, but it does warm the soil.

There is planter’s paper mulch which offers good weed control, lets water permeate, and is biodegradable as well. Landscape fabric provides excellent weed control, allows water and air to permeate but does not raise the soil temperature. It is four times more expensive than plastic, but it is longer lasting and can be reused.

The above products serve different purposes. You need to determine what factors you wish to control the most and how much you want to spend.