Train shrubs to grow tight along wall

Espaliered plants are used for softening large blank spaces on walls or fences. To train espaliers, twigs and branches are bent when they are young and flexible to meet design requirements.

Carefully tie the branches in place with raffia or plastic tape. The ties should be secured loosely so the flow of water and nutrients through the stem is not constricted. Adjust ties during the remainder of the growing season as necessary.

• When planting a container, mix different heights of plants for a layered effect.

Try something different from the typical tall plant in the center with a ring of shorter plants around it. Include plants that will cascade over the edge.

Think of your containers as large, exuberant floral displays when choosing plants. Combine different sizes of containers in each group for a good effect. A simple design of only one variety of annual planted in each container can also be beautiful and have a dramatic effect in the landscape.

• There are not many ash trees left in the Chicago region because of the emerald ash borer. If you still have an ash tree, continue treating it every one to two years depending on the product you use. Otherwise, replace your ash tree with a different type of shade tree. I chose to remove the ash trees in my home garden and replace them with other tree species a few years ago.

• Watch for garlic mustard and star of Bethlehem weeds in your garden.

Garlic mustard has small, white flowers with four petals. It is a biennial, so it flowers in its second year and produces lots of seed. It is best to hand-pull flowering plants and discard them in the trash.

Star of Bethlehem is flowering in my garden now with attractive, six-petal flowers. It is best to carefully dig out the plants to reach as many of the bulbs underground as you can. Because this is a tough plant to eradicate, discard them in the trash. Plants I have dug out and left above ground in the hot weather have continued to grow and flower.

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