Taming the Unruly Perennial Garden: Late-Summer Rescue Strategies

Rekindle Your Love for the Late-Summer Garden

By late summer, many perennial gardens look ragged: bare spots where Oriental poppies faded, globe thistle and sedum splayed open, weeds like creeping Charlie invading the lavender. It's tempting to retreat indoors. But with a few strategic moves, you can restore order and set the stage for a better next year.

In some gardens, Solidago rugosa (rough-stemmed goldenrod) is a thug—spanning five feet in three seasons. Yet its feathery foliage adds delicate texture and its flowers shine in late summer. Regular division keeps it in check.

Identify Friends and Foes

Over the years, most gardeners accumulate a hodgepodge of perennials. Among them are "thugs"—rampant self-sowers and aggressive spreaders that make a mess and don't play well with others. If you have a wild area where they can run, fine. Otherwise, remove them. Thugs I've gradually eliminated include:

• Helianthus angustifolia (perennial sunflower)
• Macleaya cordata (plume poppy)
• Anemone vitifolia (grape leaf anemone)
• Oenothera speciosa (evening primrose)
• Physostegia virginiana (obedient plant)
• Convallaria majalis (lily-of-the-valley)
• Artemisia ludoviciana (Silver King artemesia)
• Lysimachia clethroides (gooseneck loosestrife)

Conversely, well-behaved perennials that don't spread, need no staking, resist pests, and are long-lived include:

• Hemerocallis (daylilies)
• Baptisia australis (false indigo)
• Astilbe
• Dictamnus (gas plant)
• Doronicum (Leopard's bane)
• Allium senescens
• Coreopsis verticillata (threadleaf coreopsis)
• Salvia superba
• Sedum 'Autumn Joy'

Baptisia australis

Set Some Boundaries

Define garden vs. non-garden space with permanent edging—plastic, metal, brick, or stone. Then mulch the designated garden area to surround desired plants and smother weeds. Fall is ideal for installing edging. Twenty-two years ago, I put heavy-duty flexible plastic edging around my perennial, vegetable, and cutting gardens. It still keeps grass out and saves hours of labor.

Seating Assignments: Move Plants to Better Spots

This back-of-the-border set (from left: Rudbeckia laciniata, Helenium autumnale, Silphium perfoliatum) shares color and flower form, and two are similar height. They'll be moved to new sites where they can stand alone.

Few plants in my garden started in their current location. Moving plants is the only way to discover what works best where. Late summer, when plants are fully mature, is the best time to plan moves—you can see height, leaf shape, texture, bloom time, and color. Walk the garden, jot observations, mark plants to move with survey flags. Once weather cools, cut them back, transplant, and water well for a couple weeks so roots establish before freeze.

Fresh Blood: Add Distinctive Features

Exceptional gardens have distinctive features—wooden pergola, well-placed sculpture, colorful birdhouses, unusual specimen tree. These elements:

• Serve as organizing principles to plant around, giving beds a sense of place and purpose.
• Draw the eye through the garden (and away from imperfections).
• Provide a unique signature present every day of the year, in bloom or under snow.

The new walk is flatter and wider, with an area near the entrance for a bench and lots of pots.

The original stone walkway was too narrow and uneven.

I'm often too close to my own 22-year-old garden to see the whole picture. Gordon Hayward's book Your House, Your Garden helped me understand how people move through a garden and how to play up distinctive features. It revealed that my poorly defined front walkway was a missed opportunity. Three pallets of stone and five weekends later, the front of my house had an entirely different, pulled-together look.

Late summer is a time to savor your garden—it's too hot to do much else! Grab a cool drink, take a stroll, and invite a gardening friend for fresh eyes. When the weather cools, you'll have fun projects to keep you busy until the ground freezes.