Malcolm McDowell Woods

Natural Gardner

By - Aug 1st, 2009 12:01 am

basilThe August garden is a lush garden and it’s time to sit back and enjoy the fruits – and vegetables and flowers – of your labor.

Give yourself credit for your successes – and consider what might be improved. Are there bare spots in the landscape? Has perennial-provided color disappeared? Use your garden log and camera to document what worked well, and get ideas for improvements such as relocating plants, dividing perennials, adding new plants or upgrading your lawn.

You can see how your garden fared but it’s very enlightening to visit a botanical garden and discover what worked for professionals. Boerner Botanical Gardens (BBG) in Whitnall Park is a great resource in our own backyard. During August and early September, Friends of BBG offer Wednesday evening garden walks focusing on roses, test garden show stoppers (future garden center selections), herbs, season perennials and more. Call 414-525-5650 or visit For information on BBG hours, fees and directions, call 414-525-5600.

Further afield, visit Olbrich Botanical Gardens and Allen Centennial Gardens in Madison, Rotary Botanical Gardens, Janesville, and the Green Bay Botanical Garden. Gather ideas and information on a fun late-summer outing.
Seasonal pick-ups

Does your garden look a bit tired? Energize containers and flower beds with new additions. You may have things on hand to move temporarily. For example, improve a container with a heuchera (coralbells), small hosta or other perennial; replant them later for winter. Before long, garden centers will offer such cool-weather annuals as winter pansies, flowering kale and mums to brighten your landscape. Cold-hardy pansies are real winners, blooming now and again in spring. In a bulb garden, they help mask declining foliage after bulbs bloom.

As we move into late summer:

• Check plants frequently for dryness, especially hanging baskets and containers; they may need daily watering – even twice daily if it’s especially hot and/or windy.
• Fertilize containers weekly.
• Deadhead faded flowers.
• Prune back leggy plants by one quarter to one-half, cutting just above a bud or set of healthy leaves.
• Add a layer of mulch around plants to keep roots cool and moist.
• Keep monitoring all plants for pests and fungal diseases.
• Check phlox and monarda (beebalm) for white powdery mildew; you may later relocate them to areas with more sun and better air circulation or replace with more resistant varieties.
• Snapdragons, garden pinks (dianthus) and French marigolds can languish in hot weather; if this happens every year, plant in a cooler location next year or choose heat-tolerant plants such as moss roses, zinnias or gazanias.

Prepare for fall and spring

Propagate especially attractive annuals including coleus, geraniums, wax begonias, fuchsias and herbs. Take a 6” cut from a healthy stem, remove any flowers and the lowest set of leaves. Dip tip in rooting hormone and place in potting soil, vermiculite or perlite. Treat cuttings as houseplants.

Divide iris, hostas and peonies in late August and September. Don’t divide Siberian iris, astilbes or delphinium until spring.

Cut iris back into a fan shape about 6” long. Dig out the rhizomes and replant healthy ones just below the soil. Split hostas with a sharp edged tool and plant so the crown (site where roots and stem join) is even with the soil surface. Peony rhizomes should be planted with the buds (eyes) 2” below the soil. Protect from fluctuating winter temperatures with mulch.

Start salvaging tender bulbs in September. Tuberous begonias, caladium, calla lilies, cannas, dahlia and gladiolas can be stored in dry peat moss or other materials. Garden expert Melinda Myers provides a helpful storage chart in her book Month by Month Gardening in Wisconsin (see

Tropicals such as hibiscus and oleander should be moved indoors by early October. You can prune them to fit interior spaces and place in a south-facing window or under artificial light. Isolate containers for several weeks to prevent insects in your house. Spray with insecticidal soap if needed.

Many gardeners like to over-winter plants such as geraniums, begonias and fuchsias. Keep them in containers, place in a sunny location and treat as houseplants. Isolate containers for several weeks first.

I treat my favorite geraniums and abutilon (flowering maple) as houseplants but do have a cool, dry fruit cellar for additional bulb and plant storage. To store geraniums, I shake dirt off the roots, remove most leaves and place plants in paper bags marked with their color. In spring, I pot up healthy ones and move them to a sunny window. This year I stored some fuchsias and angel wing begonias in their containers in the fruit cellar. I cut them back, put the containers on trays of fine gravel and watered monthly. In March I moved them to a sunny location and resumed regular watering and fertilizing.


Hybrid tea roses prefer a spring planting but hardy shrub and landscape roses can be planted through early fall. You can over-winter miniature and tree roses by moving them inside to a sunny location.

Generally limit pruning to dead, damaged or diseased canes. Do not prune climbers or ramblers in the fall or you will eliminate their spring bloom. Check UWEX and other resources for winter protection guidelines.

Trees, shrubs and lawns

Late summer/early fall is a great time to add shrubs, trees or sod as cooler temperatures allow them to establish healthy root systems. Avoid pruning that can stimulate late-season growth and don’t prune sub shrubs such as Russian sage or butterfly bush; wait until late winter/early spring when they are dormant.

Check your lawn and provide help as needed, including re-seeding thin or bare spots. If more than half of a lawn’s green color consists of weeds, replace it! Don’t fertilize established lawns until September. For helpful lawn/turf information, check UWEX and other resources.

Is Creeping Charlie your personal challenge? The best time to apply a broadleaf herbicide or weed killer is after a hard frost; spot treat areas to reduce the amount of chemicals.

If you have moss or mushrooms, increase sunlight by having a certified arborist thin tree canopies. You can also add organic matter to the soil and choose a shade tolerant grass and/or groundcover.
Bulbs, bulbs, bulbs

October signifies bulb planting to many people – but you can plant until the ground freezes. To avoid premature sprouting, don’t plant before early October.

Be creative and add new varieties such as winter aconite whose cheery yellow blooms appear very early. Introduce bulbs to additional areas such as perennial beds where they provide early color. If you start new beds, work organic matter into the top 8-12 inches of soil before planting.

Fluctuating winter temperatures can damage bulbs; if you choose especially expensive or tender types or plant late, add a layer of mulch. Protect bulbs from squirrels by placing screening over the bed. Another no-cost idea is to save the thorny branches when you prune your roses and lay these over the bulbs.

A veggie cornucopia

August and September are payoff time for vegetable growers. However, this is the time when hot and humid conditions promote insect or disease problems; so keep monitoring plants.

This is the time you can:

• Plant seeds for short season crops such as lettuce, greens, spinach and onions. But check maturation time to assure a harvest before the first killing frost; remove excess plants so remaining seedlings thrive.
• Protect maturing melons and vine crops from rot; place mulch or downturned plastic lids under the fruit.
• Keep mature-appearing tomatoes on the vines for a few extra days to enhance flavor.
• Dig and pot chives and parsley by September to take indoors.
• Take 3-4” cuttings of oregano, rosemary, sage, etc. Dip tips in rooting mixture, pot in vermiculite, perlite or potting soil and keep as houseplants in sunny spots.
• Move larger rosemary or sweet bay plants inside (by October.)

Once the garden is put to bed, you can enjoy a well-deserved break – but if you want to think ahead, you can find helpful and fun resources to spark your creativity. Check the winners of All America Selections on or visit the Chicago Botanic Garden site that includes both a plant and problem search.

The University of Wisconsin Extension provides information on many topics including insect and disease problems. Resources include:

• InfoSource:
• UWEX publications to purchase or download:
• Wisconsin Garden Facts:
• Milwaukee County UWEX:
• Milwaukee County Horticulture Helpline at 414-256-4664, Monday through Wednesday from 9 a.m. to noon.
• UWEX Horticulture Center at BBG, daily from 10 a.m. to 2 p.m. until September 30.

Overwhelmed with a bountiful harvest?

Share it with Harvest for the Hungry or a local food pantry. Another idea is to enroll in Practical Produce on October 3, a class offered by Friends of Boerner Botanical Gardens to provide information on picking, preparing and preserving fresh produce. Call 414-525-5650.

-Peg Fleury

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