Grass lawns will be OK if allowed to go dormant

Established bluegrass lawns need an inch of water a week to continue to actively grow and stay green throughout the summer. Water deeply once a week rather than lightly multiple times a week. This promotes a deeper root system so the grass will hold up better to stress.

To determine how long it takes your sprinkler to deliver 1 inch of water, set out a coffee, tuna or other shallow can with straight sides and time how long it takes to fill it with an inch of water. Be consistent with your watering practices; either water on a regular basis all summer or let your grass go dormant during hot, dry periods.

If your soils are heavy and long periods of watering start to run off, then you may need to split watering into a couple times per week. The consistent rain and moderate temperature have kept lawns green and growing through June. Mowing your lawn at a height of 3 inches or more will also help the grass withstand stress and keep out weeds.

I do not water my lawn, and I allow it to go dormant in the heat of summer and shift to mowing once every two to three weeks.

• Prune shrubs that put on a lot of growth this year. Prune them as needed to keep them in the proper scale for your garden. Growth will be mostly hardened off in early July, so there should be minimal new growth when pruned at this time.

Try using a pair of hand pruners instead of an electric hedge clipper to create a more natural look by making individual cuts at different heights throughout the shrubs. For a more formal look, make cuts at the same height. Prune right above the leaves to help hide the cuts.

Careful pruning will leave the plants smaller but not looking “sheared.” Remove dead wood as necessary.

• Some varieties of crabapple are very susceptible to a fungal disease called apple scab, and those not treated in spring may be losing their leaves at this time. The remaining leaves will develop black and yellow spots.

Spraying with a fungicide at this point will not help, but give the affected tree extra care by providing supplemental water as needed and fertilizing in the fall or next spring. Consider replacing disease-prone trees with resistant varieties.

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