Rain creates extra pruning needs

Plants have been putting on a lot of growth this summer after the series of rainstorms and the shrubs that you pruned in June and or early July may need to be touched up again. I have been seeing more late-season growth on shrubs than in years past.

Be careful when pruning spring flowering shrubs like fragrant viburnum and lilac that have set flower buds for next year; over-pruning now will remove next year's flower display.

• Be sure to check the oil and clean out the air filter on your lawn mower on a regular basis. The engine can be ruined by letting it run out of oil. The dust raised when mowing over dry leaves later in fall can clog up the air filter, which will impair performance of the engine.

It is a good idea to sharpen your mower blades after about every eight hours of mowing.

• Look for woody plant weeds like mulberries, buckthorn and boxelders that seed and grow among shrubs and in hedges. I have tree seedlings regularly popping up in my perennial borders. These weeds tend to be hard to spot when they are young.

They can also grow alongside and into fences making them difficult to remove. Try treating the stumps with an herbicide like Roundup that contains glyphosate immediately after cutting to kill the root system and save you the trouble of digging out the stump.

• The gladiolus produces a large, showy flower spike that lasts for several days whether in the garden or in a vase. To get the most out of a bloom for decoration inside, cut when the lowest blossoms have begun to show color.

Place the cut stem in water as quickly as you can. Stagger the planting of gladioli to provide flowers over a longer period.

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