What to do in your garden in July
Daylilies These heat-loving perennials come in every shade of apricot, lavender, orange, pink, purple, red, and yellow. Choose from hundreds of varieties, including miniatures or flowers with contrasting centers, ruffled edges, and broad or narrow petals. Consider trying one or several from the long-blooming Starburst series: yellow-and-red 'Black-eyed Stella'; yellow 'Happy Returns' and 'Stella de Oro'; and red 'Pardon Me'. Daylilies grow best when the soil has been amended with plenty of organic matter, and produce the greatest bloom when given adequate water (don't allow the soil to go dry).
Add heat lovers Many perennial flowers drop their buds and stop blooming during July's high temperatures, but you can perk up your garden with heat-loving flowers. For irrigated beds, plant compass plant (Silphium laciniatum), coreopsis, ox-eye sunflower, purple coneflower, rudbeckia, and Shasta daisy. In dry gardens, grow Blackfoot daisy, blanket flower, chocolate flower (Berlandiera lyrata), golden aster (Heterotheca villosa), and pinnate prairie coneflower (Ratibida pinnata).
Start morning glories Sow seeds of these fast-growing, heat-loving annual vines next to fences and trellises for showy, trumpet-shaped flowers later this summer. To speed up sprouting, nick each seed with toenail clippers and soak in water overnight before sowing. Look for Ipomoea cultivars that come in a range of colors including cherry rose and white ‘Rosita’; reddish 'Scarlett O'Hara'; ruffled magenta 'Sunrise Serenade'; and tricolored lavender, magenta, and purple Early Call mix.
Try sedums Plant wherever you need instant color that returns year after year. All sedums have handsome succulent foliage and bloom clusters late in the season that persist through the winter as dried flowers. Popular 'Autumn Joy' is the gold standard, but new varieties come out every season. 'Frosty Morn' and 'Lajos' have variegated foliage; 'Black Jack', 'Lynda Windsor', and 'Purple Emperor' have burgundy to purple foliage; 'Stardust' has white flowers.
Care for containers Monitor soil moisture twice daily. When the soil is almost dry, water the container until it leaks out the drainage holes (test to make sure the soil is thoroughly moist). Add a few drops of liquid fertilizer to the water whenever temperatures exceed 80°. Rotate containers frequently so that sunlight reaches all sides evenly (for heavy pots, set them on stands with casters).
Deadhead flowers When flowers start to fade, snip off individual blossoms or cut spikes and clusters back to a new bud or healthy leaves. When the whole plant looks unkempt, cut stems down to basal foliage. Don't deadhead flowers on varieties grown for their attractive seed heads, such as Baptisia, bear's breech, butterfly weed, gayfeather, and sea lavender. When insects, powdery mildew, or rust damage the following plants, cut them down to the ground: columbine, cranesbill, hollyhock, lady's-mantle, lamb's ears, Shasta daisy, and summer phlox.
Green up lawns Bluegrass goes dormant and turns brown when temperatures regularly exceed 90°. If your community allows you to keep your grass green in summer, temporarily increase irrigation to every other day. If patches turn brown, set a sprinkler in that area to apply extra water. You can also stop fertilizing, raise the mowing height to 3 inches, and mow more frequently to prevent leaf scorch. If allowed to go dormant, bluegrass will generally green up again in late summer.
Divide irises Divide bearded irises while they are semidormant, about six weeks after they finish blooming. Use a spading fork to dig up the entire clump, and snap or cut off each leaf fan, leaving 3 to 4 inches of the thick horizontal rhizome attached. Then trim leaf fans back to 6 inches. Amend the soil with 4 inches of compost and a handful of fertilizer. Dig a shallow basin and set in the rhizomes, leaf fans pointing out, in a circle. Cover all roots that extend downward from the rhizome and bury the rhizome with a shallow layer of soil.
Prevent fertilizer burn Use care when applying either liquid or granular fertilizer when daytime temperatures exceed 90°, so you don’t badly scorch the foliage or, in severe cases, kill the plant. Apply fertilizer on cloudy days early in the morning, late in the day, or when rain or cool weather is forecast. Follow label directions exactly and don’t use more than the recommended amount. If rain doesn’t come, water well and rinse liquid products off foliage.
Water All landscape plants, including lawns and xeriscapes, require careful monitoring of soil moisture during prolonged hot and dry spells. Once a week, check soil every few feet throughout your property with a moisture monitor, available from most garden centers and home improvement stores. If soil is dry several inches deep, water more often until weather cools. Allow xeriscapes to dry out thoroughly between waterings.
Slugs and snails These pests hitchhike into your yard as eggs on nursery stock. Look for gray slugs and brown snails around compost bins and irrigated parts of the garden, especially early in the morning, in the evening, and on cool, overcast, or rainy days. Destroy slugs and snails or put them in a bag and toss them in the garbage. To attract and drown them, sink a shallow dish of beer in the soil around favorite plants; clean regularly.
More: Plant a showy coleus
Plant a showy coleus
'Henna', a striking new coleus, is a must-have for the summer garden. It grows 2 feet tall and 16 inches wide, and can fill a medium-size pot all on its own. But in lightly shaded beds and pots, its scalloped leaves ― splashed with copper and lime ― pair well with trailers such as chartreuse Lysimachia nummularia 'Aurea' or Ipomoea batatas 'Marguerite'.
Grow it beside bronze Carex flagellifera 'Toffee Twist' and terra-cotta-colored calibrachoa. Pinch off flower spikes as they develop, and water regularly through the warm months. –Julie Chai