The Ornamental Garden in July

Despite July’s sultry temperatures, the sunny border should look spectacular this month as the sizzling hot colors of daylilies, coneflowers, zinnias, marigolds, coreopsis, garden phlox, and much more light up the landscape.

HOW TO PLANT A CONTAINER GARDEN

If tending a large garden is not your idea of a fun way to spend your spare time, perhaps a container garden is more your speed.   One of the most popular approaches to creating a container garden is the “thriller, filler, spiller” method – something for height, something to fill in the middle, and something to spill over the side of the pot.   Although easy to create, they do require some careful planning and maintenance to keep them looking attractive all summer long.  Here are a few pointers that might help:

• Containers. Many people fail to select a container that is large enough or deep enough.  As the plants grow, their roots need enough room to move down into the soil inside the pot to take up nutrients and water.  As the roots fill up the pot, the soil dries out faster.
• Plant Choices. The sky is the limit when it comes to plant choices for container gardens. Just keep in mind that, in general, drought-tolerant plants work better in container gardens than moisture loving plants, particularly if the container is in a sunny location.  Drought-tolerant plants are better equipped to handle the drier soil and intensified heat of a container garden.  If your container will be in a shady spot, then choose plants that can tolerate shady conditions.
• Color Choices. Keep the color palette fairly simple with two or perhaps three colors. More than that can look really busy at best and chaotic at worst.  One of the easiest approaches is to use two shades of the same color, such as lavender and purple or pink and rose.  Another easy approach is to use complementary color combinations:  orange and blue, yellow and violet, or red and green.  And don’t forget to think about your use of foliage and how it will harmonize with the flowering plants.   Consider the color of the container and how it will impact your palette.
• Proportions. Now, about those thrillers, fillers, and spillers.  One of the easiest ways to ruin a container garden is to disregard the concept of proportion.   Among other things, this means keeping in mind the mature size of all the plants in the composition.  A “thriller” is the vertical element of the composition and should be in proportion to the height of the container. In other words, a general ratio to strive for is one-third container to two-thirds plant height.   “Fillers,” particularly those with a mounded or rounded shape, provide the horizontal interest in the composition and balance out the overall effect. They should gracefully fill in the space between the thriller and the rim of the pot.  A “spiller” grounds the composition, tying it to the container.  Spillers look best if allowed to cascade gently or trail gracefully toward the outer bottom of the pot. If it sprawls too aggressively, it can look like an escapee creeping across your patio.
• Cultural Requirements. Last but not least, take into consideration the cultural requirements of a container garden. Choose plants that have the same or similar cultural requirements for sunlight, nutrients, and water.   As plants mature, they soak up water more readily.  Monitor moisture DAILY.  If the container is in full sun, you may need to water twice daily.  Just don’t overwater.  Also, because all the plants are competing for nutrients in the limited amount of soil in a container, it’s wise to use time-released fertilizers when the container is originally planted and then foliar fertilizers thereafter, as needed.

If you are interested in more information on container gardening, the University of Illinois Extension Publication on Container Gardening may be of interest to you.

HOW TO KEEP THE SUMMER GARDEN LOOKING FRESH AND INVITING

As any gardener knows from experience, July’s heat and humidity can dampen our enthusiasm for working in the garden.  However, a good strategy is to work in the cool hours of the morning or evening.  Just 10 or 15 minutes a day maintaining your garden can make a huge difference in how it looks and performs.  Here are a few suggestions (for new gardeners) or reminders (for seasoned gardeners) for keeping your garden looking perky and well maintained despite the heat:

• Deadhead spent blossoms. A few minutes per day spent deadheading results in a neater appearance of the garden in general.  For many plant species, deadheading triggers the production of more blossoms.
• Trim plants of old, tired, or tattered-looking foliage or damage caused by pests or disease. Large-leaved plants, such as hostas, look much perkier if you trim off the leaves that have suffered heavy slug damage.
• Treat foliar diseases as soon as you spot them. Don’t wait until the plant is completely ruined. With this spring’s wetter-than-normal weather, you can expect more fungal diseases in the garden.
• Speaking of plant diseases, try to select disease-resistant plant varieties when possible. For example, garden phlox (Phlox paniculata) and bee balm (Monarda) are two plant species that are highly susceptible to powdery mildew.  However, a number of cultivars or selections show very good or excellent resistance, according to published plant trial data.  To learn more, check out the following on-line publications:  North Carolina State University Publication on Mildew Resistant Garden Phlox and the Chicago Botanic Garden’s plant evaluation findings on A Comparative Study of Phlox Paniculata Cultivars and Monarda and Powdery Mildew Resistance.
• Selectively cut back or shear plants that have finished blooming to spur fresh new growth and perhaps some re-bloom as well. For general information on perennial plant care, see the Virginia Cooperative Extension’s (VCE) publication 426-203 on the culture, maintenance and propagation of Perennials.  For the new gardener who would like more detailed information on perennial plant maintenance, Tracy DiSabato-Aust’s book on The Well-Tended Perennial Garden is a useful, well-organized resource on the subject.
• Stake or cage taller perennial species to keep them from flopping over or collapsing. Plants fall over for many reasons, including too much weight from flowers, too much moisture, too much shade, or overly rich soil.  A number of plants may simply be cut back, pinched, or sheared to keep their height under control without loss of blooms.  Goldenrod, asters, balloon flower, tall daisy species, catmint, and boltonia fall into that category.  Other plants should not be cut back but staked or caged instead to avoid damaging flower buds.  Lilies, hollyhocks, foxgloves, and Crocosmias fall into this latter category.
• Pinch back fall-blooming perennials, specifically chrysanthemums and asters, prior to mid-July to keep their overall dimensions under control and to prevent them from setting buds before fall.
• Neatly edge flower beds and replenish mulch as needed. This is one of the simplest and most effective ways to make your garden look fresh and inviting.
• Monitor moisture levels. In the absence of adequate rainfall, provide supplemental water to plants as needed.  Infrequent deep watering is generally best for established plants.  This encourages them to send their roots deeper into the soil, which helps them become more drought tolerant.   Plants that are becoming established in the landscape should receive about an inch of water per week.  Newly installed trees and shrubs may require more water, particularly during their first year or two in the ground.
• Select plants with glossy foliage, which always look fresh no matter how muggy the weather is. Consider shrubs such as holly species, glossy Abelia, Camellia, or Calycanthus floridus (Carolina Allspice).  Perennials with glossy foliage include Bergenia (pigsqueak), Chelone (turtlehead), Asarum (wild ginger), some Heuchera (coral bells) species, and some hosta species.  A couple of annuals with glossy foliage include wax begonias and Madagascar periwinkle.
• Keep the garden from looking crowded and overgrown. Dividing some of those overgrown perennial clumps and thinning them out will improve the overall appearance of your garden.  While fall is preferable for dividing most perennials, some may be safely divided in summer in the absence of a drought.   If you do attempt to divide your perennials in the summer, choose a cool, cloudy or overcast day to do it.  Water the plants deeply the day or evening before so that they are well hydrated.  Dig them up, divide them, and plant the divisions right away so that the roots don’t dry out.   Give the divisions some protection from the sun while they become established.   Keep them well watered for the remainder of the summer.

WATER-SAVING TECHNIQUES DURING SUMMER

Rainfall is often sparse at this time of year.  Lack of adequate moisture stresses our gardens, causing many of our plants to wilt, develop brown edges on the leaves, or simply die.  Flowers may fail to appear or they may fade more quickly in the absence of water.  Drought-weakened plants tend to be more susceptible to disease and insect damage.  Even if your plants do survive drought conditions this summer, they may not be as hardy once winter arrives.  Trees and shrubs, in particular, may take years to recover from a drought.   To help your landscape plants thrive despite summer’s hot, dry weather:

• Water plants in the cooler, early morning hours so that the water will soak into the ground rather than evaporate into the air.
• Water plants deeply, giving them about an inch of water per week. Avoid sprinkling plants from overhead.  That just moistens the top of the soil but it doesn’t put water down at the root level where it’s needed.
• Use drip irrigation or soaker hoses under the mulch to water slowly and deeply at the base of each plant. If you don’t have drip irrigation, use a hose with an adjustable nozzle or a watering can to deliver water only at the base of each plant. Don’t water the foliage.
• Use a 2 to 3-inch layer of mulch to help hold moisture in the soil and to help protect plant roots from the summer heat.
• Group plants together that have the same requirements for sunlight and moisture.
• Consider replacing water hogs with drought-tolerant plants.
• Keep flower beds weed-free. Weeds compete with your ornamental plants for the moisture in the soil.
• Deadhead your flowering plants to prevent them from expending energy setting seed.
• Avoid fertilizing plants during a drought. That merely encourages the plants to develop more foliage.  Needless to say, the more foliage, the more water is needed to support the plant.  Another reason to avoid using fertilizer is because it needs to be watered in.  If it is not watered in, it can build up in the soil and damage plant roots.
• Capture water from your roof, using rain barrels or cisterns.
• Amend the soil with plenty of organic matter to improve moisture retention as well as provide nutrients to the soil and stimulate beneficial worm activity. If you do this in the spring, your plants will be better prepared to withstand drought conditions throughout the summer.

For more information on the subject, see VCE Publication 426-713 on Creating a Water-Wise Landscape.

WHAT’S OLD IS NEW AGAIN

If you’re the “cutting edge” type of gardener eager to try the latest hot new plant, the garden centers certainly won’t let you down.  Every year, plant developers compete with one another to see who can come up with the snazziest new color combination or hybrid.  Running counter to this trend is a resurging interest in what we think of today as “old fashioned” plants such as hollyhocks, four o’clocks, sweet peas, sweet William, heliotrope, ageratum, and sweet alyssum.  In addition to growing these plants for their nostalgic value, they are worthwhile incorporating into our gardens because they are generally hardy, dependable, and trouble-free.  Another plus is that many of them have pleasant fragrances that have been bred out of some of our modern-day hybrids.  While it’s always interesting and fun to see what’s new out there in the world of horticulture, just how many “new and improved” bi-color petunias do we really need anyway?

IT’S A BUG-EAT-BUG WORLD OUT THERE!

Keeping insect populations under control is one of the biggest challenges gardeners face at this time of year.  In general, insects fall into two camps:  beneficials or pests.  Here are two examples of commonly found insects that are seldom seen during the day but play a significant role in your garden after dark:     

• Ground Beetles are the unsung heroes in the battle against garden insect pests. Of this huge family of insects, approximately 2,500 species may be found throughout the United States.  Most ground beetles have shiny, sometimes iridescent, black, blue-black, brown, or green hard shells on flattened bodies with narrow heads.  They are equipped with large mandibles that they use to capture their prey.

  

  These nocturnal creatures feed at night and hide during the day under mulch, leaves, rocks, boards, or logs.  They have wings but seldom fly, opting instead to scamper quickly away when disturbed.  Both the adult and larval forms of ground beetles have voracious appetites and prey on a variety of insect pests, including asparagus beetles, cabbage root maggots, Colorado potato beetles, corn ear worms, cutworms, slugs, and snails.  They prey on both soil-dwelling pests as well as plant and tree pests, including Gypsy moth larvae, squash vine borers, tent caterpillars, and tobacco bud worms.  If you are really curious to know more about this beneficial insect, perhaps you’ll find the North Carolina State University’s publication on Ground Beetles useful.

• Earwigs are considered to be either beneficial insects or pests or both, depending on your point of view. Anatomically, they are one of the stranger-looking insects in the garden.  Large pinchers emerge from the tips of their abdomens giving them a ferocious look.  In truth, they are generally harmless to humans. Mostly nocturnal creatures, they feed on plants at night and hide during the day in moist, dark places, such as mulch, soil, plant debris and under rocks and boards. They are considered a nuisance insect because they feed on the flowers and foliage of a wide range of plants, leaving irregular holes or ragged edges.  The damage they cause is similar to that of slugs and snails.  Despite their destructive eating habits, earwigs do have some useful qualities.

  

  They are omnivorous and help break down organic matter in compost piles.  More importantly, they are natural predators of aphids, mites, nematodes, insect larvae, slugs, snails, and other slow-moving insects.  In turn, natural predators of earwigs include birds, toads, and insect predators.  If the earwig population is out of control in your garden, place a rolled up newspaper, bamboo tube, or short piece of old garden hose on the soil near your plants just before dark.  The earwigs will crawl inside during the night. The next morning, shake out the accumulated earwigs into a bucket of soapy water.  For more information on this peculiar-looking insect, see VCE publication 3101-1527, Earwigs.