July in the garden: Moist spring makes July good for shrub trimming

Cool and moist conditions throughout spring have been great for the early flowers and have brought on lots of tree and shrub growth. Early July is a good time to prune your shrubs to control their size and shape. If you wait until later in summer, watch out for flower buds on spring-flowering shrubs such as lilacs and fragrant viburnums; heavy pruning of these shrubs late in the season will reduce next year’s flowers.

The wet spring also brought on plenty of weeds. Weeds are easier to pull out when the soil is moist, but you should be careful to minimize foot traffic on wet garden soil.

General garden careBe careful when pulling heavy hoses around the garden for watering. Install hose guides at strategic points to keep hoses from dragging across plants. Quality hose guides can be decorative as well as practical. Heavy, low-to-the-ground guides staked into the soil work best. I generally top-dress perennial beds with about 1 inch of mulch and shrub beds with 2 inches. To determine the amount of mulch needed for your garden, calculate the square feet of the bed. (Divide an irregularly shaped bed into smaller, simpler shapes; calculate the area of each and add them up.) Use the following calculation to cover a 56 square foot bed with 2 inches of mulch: Divide 2 inches by 12 inches to convert the depth of mulch to feet instead of inches (0.17). Next, multiply 0.17 feet by 56 square feet of area to determine how much mulch is needed: 9.5 cubic feet. I would round this figure up to 10 cubic feet. At garden and home centers, mulch is sold in bags containing 2 or 3 cubic feet. Consider buying mulch in bulk from a garden center or landscape supply dealer for large areas. A floral shovel works especially well for plants that are too big to plant with a trowel, such as 1- and 2-gallon containers. The blade size (6 by 8.5 inches) is smaller than a standard round-point shovel, which makes it good for maneuvering in tight spaces. Watch for Japanese beetles in your garden. They have a distinctive green-gold metallic color and a fondness for plants in the Rosaceae family. Roses are particular favorites of theirs. Early morning is a good time to pick the beetles off plants; drown them in a container of diluted detergent. For large ornamental areas with a heavy infestation, spraying with an insecticide labeled for Japanese beetles is an option.Traps are not a good choice for controlling Japanese beetles. They have a lure inside, which will only attract beetles to your yard. They are best used for monitoring populations.Before treating with any insecticide, it is important to identify the insects you find your plants. Not every insect is a problem, and the presence of insects feeding on the plants should not warrant automatic treatment. Some insects are beneficial and help control other insects naturally. If you do identify a problem insect, try to assess whether the amount of damage being done warrants control. If you decide to use a chemical control, it is important to use the correct one with proper timing. If a variety of treatments are available, use the least toxic alternative.Trees and shrubs This is the time of year to check magnolias closely for magnolia scale, an insect about the size of a pencil eraser. Typically found on the underside of branches, the scale insects can thin out the tree. They suck the tree#146;s sap and exude a clear sticky honeydew after feeding. Black sooty mold, a fungus, grows on the honeydew. Though the mold itself is not a real problem, gardeners often notice it on or under the magnolia before noticing the actual scale insects.On small trees, simply pick off the scale insects and squash them. Other control measures include spraying with summer-weight oil, or applying an insecticide when the scale is in the active crawler stage of its life cycle, generally in early September. For trees with a history of magnolia scale, a late winter to early spring application of dormant oil will provide good control. If your tree is affected, provide extra water during summer to minimize stress. Some varieties of crabapple are very susceptible to a fungal disease called apple scab, and those not treated in spring may have lost many of their leaves by late July. The remaining leaves will develop black and yellow spots. Spraying with a fungicide at this point will not help. Do give the affected tree extra care by watering as needed and fertilizing in fall or next spring. Consider replacing disease-prone apple trees with resistant varieties.Espaliered plants are used for softening large blank spaces on walls or fences. To train espaliers, bend twigs and branches to fit the design when they are young and supple. Carefully tie the branches in place to a fence or to screw eyes in a wall using soft, flexible raffia or plastic tape. The ties should be secured loosely so the flow of water and nutrients through the stem is not constricted. Adjust the ties during the growing season as necessary.Prune shrubs that have put on a lot of growth this year to keep them in the proper scale. Spring growth will be mostly hardened off in early July, so there will be little new growth when shrubs are 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. Remove dead wood as necessary. Careful pruning will leave the plants smaller but not looking sheared. Prune out water sprouts (vigorous shoots on the inside of the tree and on the trunk) and suckers (vigorous shoots growing from the base of the plant). Crabapples and hawthorns tend to send out lots of water sprouts and can benefit from this type of pruning.Control large woody weeds such as buckthorn and box elder by cutting them at ground level and immediately treating the stumps with an herbicide to kill the roots. Simply cutting them down will just result in a thicker, bushier plant as the plant re-sprouts from the roots. Stumps also can be ground out with a stump grinder. But the grinder typically only removes the stump a few inches under the ground, which can make it difficult to install a large replacement tree in the same location.Construction projectsConstruction work can compact your garden soil and cause many problems for plants in the future. When you start a construction project in or near your planting beds, work with your contractor at the onset to make sure he is sensitive to your home#146;s soil condition. Fence off trees#146; root zones and garden beds if you can to keep foot traffic and construction equipment off them. Try to have crews reserve 12 to 18 inches of topsoil to return to the beds at the project#146;s end. After the project is finished, be sure any compacted soil is thoroughly loosened up before replacing the topsoil; it is best to remove any heavy clay fill left over from excavation work. A good profile of topsoil that has not been compacted or contaminated with heavy clay will be a good foundation for your future garden.If your property is under construction for a new patio, sidewalk or driveway, consider installing a PVC pipe sleeve beneath the concrete, pavers or asphalt. This tube will make it easy to install future irrigation or lighting. Paths and patios built with a sand base need to be top-dressed with additional sand occasionally to fill in between the joints. This will keep the bricks stable. Take care when using a leaf blower that you do not blow out the sand. New brick or paver work will need a couple of top-dressings as rain settles the sand between the joints. The heavy rainfall in spring and early summer may have exacerbated drainage problems in your garden. Installing drain pipe (usually called drain tile) can help in certain situations where soils are too wet.Adding a drain will not help your soggy conditions, though, if it does not move the water out of the saturated area. The drain should be installed in the lowest area of the garden and it must slope evenly to a place where the water can flow away. The soil above the drain should not be compacted or heavy clay, which would prevent rainwater from soaking down to the drain. If you have catch basins as part of an existing drainage system, be sure to clean debris out of them on a regular basis. Installing a dry well by digging a hole and filling it with gravel will not help with drainage, because the water that collects in the well has nowhere to go.LawnsEstablished bluegrass lawns need 1 inch of water a week to continue to actively grow and stay green throughout the summer. To determine how long it takes your sprinkler to deliver the equivalent of 1 inch of rainfall, set out a coffee, tuna or other shallow can with straight sides and time how long it takes to fill with 1 inch of water. Water deeply once a week rather than lightly several times a week. This promotes a deeper root system that will help the grass stand up to stress. If your soils are heavy and water begins to run off after a long period of sprinkling, you may need to split watering into a couple of sessions per week. Be consistent with your watering practices: Either water on a regular basis all summer or let your grass go dormant during hot, dry periods. Mowing your lawn at a height of 3 inches or taller will also help the grass withstand stress and keep out weeds.ŸTim Johnson is director of horticulture at Chicago Botanic Garden (chicagobotnic.org). 22421501If pruning in late summer on spring-flowering shrubs, such as this lilac hyacinth, watch out for flower buds or you will cut down on next year’s blooms.Chicago Botanic Garden 15691039Early morning is a good time to pick Japanese beetles off plants; drown them in a container of diluted detergent.Chicago Botanic Garden