The Ornamental Garden in July

  • By Pat Chadwick
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  • July 2016-Vol.2 No.7
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July is the month when our ornamental gardens are usually at their peak.  It’s also the month that we feel the full force of summer heat and humidity.  As you tackle your gardening chores, take precautions to avoid heat stroke and sunburn.  Work in your garden early in the day — the earlier, the better.  Drink plenty of water to stay hydrated, wear a hat and sunglasses, and use plenty of sunscreen.  Give yourself an occasional break from your labors to enjoy your garden.

Maintain Your Ornamental Beds

  • Deadheading – Spend a few minutes each week deadheading spent blossoms.  Yes, I know it’s hot outside and the humidity makes your hair do weird things.  But you’ll congratulate yourself later when your garden continues to bloom while more complacent neighbors’ gardens fizzle out.
  • Watering — As temperatures soar this month, it’s particularly important to monitor moisture levels in the garden, especially for newly planted trees, shrubs, and perennials.
  • Weeding – This is one of those never-ending chores that most ornamental gardeners detest. But here’s why it’s important:  Weeds have an amazing capacity for self-preservation.  For example:
    • Oxalis (Yellow wood sorrel) – This particularly prolific annual weed is highly successful at reproducing itself.   It looks innocent enough with its cute little yellow flowers and clover-leaf shaped foliage.  But when those flowers give way to seed capsules, that’s when this bad boy literally springs into action.  As the seed capsules dry, they explode, throwing the seed several feet away.
    • Ragweed – This summer annual produces an amazing quantity of seeds in late August through September.  One plant can have between 30,000 and 62,000 seeds.  Should any of those seeds become buried in the soil, they can remain viable for decades.
    • Horse Nettle – This perennial weed reproduces by seed as well as by an extensive root system.  If you dig it out of your garden (rather than use an herbicide), it’s important to remove all of the roots.  Any root fragments left in the soil can remain viable for years and will wait patiently to sprout until growing conditions are ideal.
    • Crabgrass – A summer annual, this weed certainly qualifies as one of the top ten nuisances in both the lawn and the ornamental garden.  It germinates from mid-spring to mid-summer and reproduces by setting seeds and by rooting at the lower joints.  To control it, dig it out by the roots and make sure you get every bit of the plant.


Tackle these and other weeds when they are small, easy to pull, and less likely to require an herbicide to control them.

Dry Flowers for Arrangements

Consider preserving some of your flowers for dried flower arrangements. Air drying is the easiest and cheapest method for preserving plant materials. For best results:

  • Cut the stems when the blossoms are either still in bud or are partially open. They will continue to open as they dry. If you’ve never dried flowers before, you may need to experiment to determine the optimal time to cut them.
  • Cut the flowers close to the base of the plant so that the stems will be as long as possible.
  • Remove the foliage from the stems.
  • Loosely gather the stems into small bunches and secure them with twine, ribbon, or a rubber band.
  • Suspend the bunches upside down from a coat hanger, hook, or clothesline in a warm, dry place out of direct sunlight with plenty of space between them for air circulation.
  • Allow the bunches to dry for two to six weeks, depending on what is being dried.


Drying flowers successfully is easy but requires patience while you learn which technique works best for your specific needs.  In addition to being air dried, plant materials may be pressed, embedded in desiccants of various kinds, and even dried in a microwave oven. For a good description of the methods that can be used to dry flowers, see Clemson Cooperative Extension publication HGIC 1151, “Drying Flowers,”

Control Potential Mosquito Breeding Sites

With escalating concerns these days about mosquito-borne diseases, it’s more important than ever to eliminate potential mosquito breeding habitats in the landscape.  Inspect your property, including house gutters, for standing water, and drain any you find.  Don’t forget to check for water in saucers under house plants.  If you have a birdbath, wading pool, or outdoor pet water bowls, replace the water in them every other day or so.  In addition to breeding in standing water, mosquitoes may also lay their eggs in soil that frequently floods or stays moist, such as ditches or low areas in meadows.  They need only a tablespoon or so of water in which to lay their eggs.

Consider using plants around your home that naturally repel mosquitoes.  Some suggested plants include rose-scented geranium, lemon balm, catnip, southernwood, allium, nicotiana, marigold, lemon thyme, peppermint and lavender.

Encourage Fireflies in Your Garden

Consider yourself fortunate if you have fireflies (lightning bugs) in your yard.  They are some of the good guys of the insect world.  Their larvae eat mites, slugs, snails and soft-bodied insects, including their larvae.  But firefly populations are dwindling, possibly due to the use of chemicals on lawns, pesticide use, light pollution, and habitat destruction.  If you want to attract more fireflies to your garden, here’s how:

  • Tackle the light pollution problem by either dimming exterior lights or turning them off when they are not needed.  Fireflies communicate with one another via light signals. Porch lights, street lamps, and garden lights can interfere with those signals.
  • Incorporate a good variety of shrubs, grasses, and perennials into your landscape to provide habitat for insects.
  • Leave an area of high grass around the perimeter of your yard.  Male fireflies fly but the females generally do not.  Female fireflies rest on tall blades of grass and shrubs and wait for the males to come to them.
  • Use pesticides judiciously. Keep in mind that chemicals intended to destroy insect pests are sometimes non-selective and make no distinction between good bugs and bad bugs.

Monitor Perennials for Disease

A highly contagious viral-like plant disease to be on the alert for is aster yellows.  It is caused by a phytoplasma, a tiny organism that is spread from plant to plant by sucking insects such as leaf hoppers. This disease affects more than 300 ornamentals, vegetables, and weeds.  It is characterized by chlorosis (yellowing of the leaves while the veins remain green), extreme leafy growth, and deformed flowers that often remain green or sometimes exhibit tufts of green foliage within a blossom or in place of a blossom. Some annuals and perennials affected by aster yellows include aster, coneflower, coreopsis, cosmos, chrysanthemum, petunia, snapdragon, marigold, and zinnia.  Other than selecting plants that are immune to the disease, there is no effective cure for it. Remove the entire plant to prevent this disease from infecting other plants in your garden.  The aster yellows phytoplasma organism will not survive once the plant dies.

Cut off the first flowers of lavender

After lavender finishes blooming, the flower stems may be cut back to tidy the plant and encourage re-blooming.  The easiest way to do this is to gather a clump of the spent blossoms in one hand and snip them off with the other hand.  This is much faster and less tedious than trimming one blossom at a time.  Just avoid cutting down into the woody part of the stem.

Lift and Divide Irises

July through September is the best time to divide irises. First, cut back the foliage to about one-third of its height. Using a spade or digging fork, lift the entire clump out of the ground. Carefully snap off the younger rhizomes from the original one.  You may need to use a sharp knife for this purpose, in which case, dip the knife in a 10% bleach solution between cuts. Each rhizome should have roots and a fan of leaves.  Plant the rhizomes at or just below the soil level about 18 to 24 inches apart.  Discard the old rhizome.

Pinch Back Chrysanthemums and Asters

If you’ve been pinching back your chrysanthemums and asters, do it one last time, no later than mid-July.   Do not pinch them back after that point.   Otherwise, the plant will not have time to set buds for this growing season.  Pinching these plants back helps keep them from splaying open in the middle and also delays bloom time until later in the growing season.

Root Cuttings of Houseplants 

July is a good time to root cuttings of non-woody house plants, such as geraniums, coleus, and fuchsia.   Make cuttings about 4 inches long.  Trim off the bottom leaves and insert the cuttings about a third of their length into moist potting medium.  Roots should develop in about four weeks.

Repot or Stabilize Large Houseplants

If they are not planted in the right pot, tall, leafy houseplants such as Ficus trees have a tendency to blow over when subjected to windy or stormy weather conditions.  A heavier pot with a wide base provides better stability than a pot that tapers toward the bottom.   Another trick is to put a brick or rock in the bottom of the pot for extra weight. Be careful not to make the pot so heavy that you have trouble moving it back indoors at the end of summer.

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