It’s a good time to plant greens

Cool-season lettuces, mesclun mixes, and other greens that were planted in early spring can be planted again this month. If the weather is unusually hot, plant these greens in partial shade or wait a few days until the temperatures cool down. The highest quality and best-tasting salad greens come from plants that are watered frequently and lightly rather than infrequently but deeply. This advice is the exact opposite of what is recommended for watering trees, shrubs, perennials, grass, and other plants.

Got grubs?

Holes in the lawn dug by raccoons and skunks indicate the presence of grubs, which feed on grass roots. Check for areas of the lawn that are browning or where the grass lifts like a piece of sod.

If there are more than 12 grubs per square foot and you are seeing extensive damage, you may want to use a product designed for quick kill of the grubs. Be sure to read the bag carefully to ensure that you are buying the right chemical for grub control at this time of year. It is important to follow the instructions for application.

Tree diseases

If new growth at the tips of your pine’s branches has turned brown, a disease called Diplodia tip blight may be the problem. It is too late to spray fungicides now, as infection occurs in the spring. Prune out dead tips in dry weather to reduce the spread of infection. Remove all infected needles from the base of the tree and discard off-site.

Some crabapples are very susceptible to a disease called apple scab, and those not treated in spring may have lost many of their leaves. Their remaining leaves may be affected with black and yellow spots. Spraying now will not help combat this disease, but you can give the trees extra care with supplemental watering as needed for the remainder of this year and fertilizing in fall or next spring. Remove all infected leaves and do not add them to your compost pile. Also, consider replacing disease-prone trees with a cultivar that is resistant.

Look for woody plant weeds like mulberries, buckthorn and boxelders that grow among shrubs and in hedges. These weedy trees tend to be hard to spot when they are young. I generally just cut them off at ground level when they are growing up in other shrubs and pull them out when they mix in with perennial borders. I also have hackberry trees that routinely sprout in my perennial borders at home.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.