Keep your rose bushes blooming longer

Deadhead hybrid roses as soon as the flowers fade. Many shrub roses are self-cleaning and don't require deadheading.

When in doubt, lightly prune old blossoms to keep plants looking attractive. Do not deadhead any roses that are being grown for their hip production.

If your hybrid roses have been losing their lower leaves and the remaining leaves have yellowish foliage with dark spots, then it is likely you have blackspot, which is a common fungal disease. Begin a spray program with approved fungicides immediately.

The fungicides need to be applied once every seven to 10 days, as they work to prevent the disease and do not cure what is already infected. Be sure to clean up any leaves that have fallen from the plants.

Many landscape shrub roses are resistant to black spot, so they do not need to be on a spray program. Do not spray Rosa rugosa, as the fungicides used to control blackspot can burn the foliage.

• Grubs can be a problem in lawns some years. The adult beetles will be attracted to irrigated lawns that are surrounded by dry lawns for their egg laying in early summer. If the season is dry and you are the only one watering the lawn on the block, you will have a greater chance of having grubs.

There has been a lot of rain this year, so the favorable lawns for egg laying are widespread. Your lawn may or may not have a problem with grubs this year, so you do not need to automatically treat for them.

Typically, when there are eight to 12 grubs per square foot, visible damage will occur as they feed on the roots of the grass. The lawn will brown out later in season when hot and dry weather increases stress on the lawn. Raccoons and skunks will dig in lawns to feed on the grubs - this is often the first sign of grubs.

Be sure to read the label carefully to make sure you are using the right product at the right time of year. Products designed to prevent grubs are generally applied late June to mid-July.

There are products designed for quick kill of grubs and are applied later in the season, when grubs reach a threshold in the lawn that is causing damage and you see the results. There is no need to control a small number of grubs that the lawn can withstand. In any case, use an insecticide labeled for grubs at the proper time of year.

I do not water my own lawn nor apply any grub controls and have never had a problem with grubs causing any noticeable damage to my turf; only minor damage that most would not notice.

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