Each season has its own particular tasks
IN A COUNTRY with so many different climates, seasonal border maintenance is tricky to write about. Nevertheless, we will attempt some general guidelines. For a large part of the United States and southern Canada, the major chores come when shorter days and cooler temperatures signal the end of the gardening season; in warmer areas, whether dry or humid, they may usher in the gardening year, and so the yearly maintenance schedule will need to be adjusted. We’ll begin by looking at the somewhat less onerous tasks of spring and summer.
Perennials with evergreen foliage, such as epimediums and hellebores, will show their flowers to better advantage if you prune away the foliage, even if it hasn’t been damaged by cold. This also benefits larger, marginally hardy evergreen plants such as Romneya coulteri and Melianthus major. If not cut back just as new growth starts, the old woody stems become decrepit, looking their worst in mid- to late summer and making an unpleasant contrast with the new growth. The much hardier Perovskia atriplicifolia is another example: if left unpruned, the old stems flop about, their woody bases subject to torsion stresses and disease-inviting injuries.
Opposite: No, it’s never fun, but staking needs to be done at the right point in a plant’s growth cycle, if it’s going to be effective. In other words, don’t wait too long. Many more recent peony cultivars have been bred for strong stems as well as floral beauty, and are less in need of staking. Above: Using small, early-blooming “marker plants” in the border can be a useful way to indicate the position of later-emerging perennials with tender new growth, such as peonies and trilliums.
If you didn’t apply mulch in fall, now is the time to do so (but take into account the caveats mentioned in the section on fall maintenance, below). Just remember that if you have self-sowers in the border, such as annual candytuft, violas, and poppies, not to mulch heavily in areas where these plants are wanted. You can always leave a few patches of ground free of mulch until after the self-sowers have germinated. If your scheme is informal, create three to five irregularly shaped drifts to give a more naturalistic impression.
Most perennials that flower later in the year (for us, after the summer solstice), such as asters and many ornamental grasses, can now be successfully divided, if you don’t put it off too late. If a plant such as a border phlox has reached a height of five or six inches before you’ve had a chance to divide it, pinch back one-half of the top growth and thin the number of stems to help offset transplant shock. Not all plants respond well to this treatment—do some research.
The more you control insects at this time of year, the less you’ll have to deal with them later. Of course, this rule applies to “stay at home” bugs as opposed to those that fly in for a visit. For example, over the past decade, various kinds of cutworms have been wreaking havoc in our gardens, often starting in late winter. Because they have no natural predators in our area, we need to stay constantly vigilant to prevent them from coring out the emerging shoots of lilies and other treats.
If a certain plant is attacked repeatedly year after year, consider removing it, or take a look at its neighbors, which might be sheltering the culprit. We once removed a Luzula sylvatica from near a Daphne xburkwoodii whose buds were being devoured, and the damage ceased.
Deadheading should begin now, especially with the large-flowered bulbs.
Aside from weeding, pinching back and staking are the main maintenance activities at this time of year. Over the years we’ve gravitated away from plants that need staking and toward plants that aren’t as prone to flopping, or that flop in a graceful way. Doing a bit of research on how a plant grows in its native habitat, or how it was created or hybridized, can help you determine whether a plant will need extra care or not.
Grooming and deadheading of spring-flowering plants should continue. If those last few lingering tulips clash with the summer color scheme, off with their heads! At this point, they’re better appreciated in a vase. Push drying bulb foliage under adjacent plants, and remove flowering tree detritus from fresh foliage and shoots.
Throughout the summer we like to remove yellowing foliage and spent flower heads that aren’t intended for fall or winter display. Even if it registers only in the subconscious, plants with large amounts of nasty-looking foliage early in the season can make an otherwise healthy garden seem tired or neglected. The spent petals of large flowers such as peonies and roses may cause fungal problems in other plants if they lodge among wet foliage. If you hate deadheading, consider adding plants that bear smaller flowers, or petals that easily disintegrate; that way, you can spend time grooming the more demanding plants without having to worry about the others.
Regular watering may be critical now, and so it pays to give some thought to whether you will have the time, and ability, to provide enough water. A plant’s size and resistance to disease can both be adversely affected by an uneven water supply, quite apart from the aesthetic drawbacks of toasted plants. It’s better to give the border infrequent but deep soakings versus a quick drink that doesn’t reach down into the root zone. If watering is proving to be an intractable problem for you, consider altering your planting scheme to one that’s more drought tolerant, or find ways to improve the conditions in your border (for example, better soil, mulch, a small tree to provide shade, or an irrigation system).
With regard to feeding, we generally liquid-feed any border denizen that has been recently transplanted. There are myriad products on the market—just be sure to follow the directions. Otherwise, we rely on the mulch that’s been applied earlier to feed the garden throughout its active growth cycle. Overfertilization, in whatever form, produces growth that is too lush and prone to wind and rain damage.
Opposite: When planting bulbs in the fall, think about how to combine them with the foliage of emerging perennials to create exciting, early-season combinations. Above left: Many evergreen perennials, like this hellebore, benefit from having their old foliage removed in early spring to make way for new leaves and flowers. Above right: This cat’s-cradle arrangement is an easy, attractive, and effective way to stake perennials.
LATE SUMMER/EARLY FALL
By this point in the gardening year, the chores shouldn’t be overwhelming. As soon as the leaves on the trees and shrubs begin to show their autumnal tints, you can ease up on the grooming. Now, when the cycle of life is returning to the earth, is the time to let the garden slow down, and to take pleasure in ripening seed heads and fruits. With colchicums, asters, and the like taking their curtain calls, it’s a good time to do a critique of the border and plan improvements for next year’s performance.
If the border has suffered through a summer drought, continue watering into the fall, since a stressed plant will not overwinter well. Otherwise, begin to cut back on water, as plants that remain in active growth late into the season can be damaged by an unexpected cold snap.
In our garden (in the maritime Pacific Northwest, USDA Zone 8), the main cleanup begins when we can no longer stand to look at certain deciduous perennials. Given our mild autumns, this can occur well before our first killing frost. Out come the hand pruners, cutting away unsightly dying foliage. Don’t worry about harming the plant—at this point in its life cycle, it’s ready to call it quits anyway.
Evergreen perennials are another story, however. For a beginning gardener, it can be hard to figure out which plants are truly evergreen and which merely “act” evergreen in areas with a mild climate. When in doubt, don’t prune! It’s much better to let the plant keep its foliage, which may afford an extra bit of winter protection.
If you’ve chosen your plants wisely, your border may only need a minor fall trimming. Many seed heads not only look good, but also provide food for wildlife. This might not be practicable in areas with wet winters, however, as heavy rains have a way of turning many plants to mush. Yet another reason to do a thorough fall cleanup is if you have a large number of plants that are prone to fungal infections during their active growth cycle, such as herbaceous peonies.
When you cut plants back, be sure to leave a bit of stubble in order to indicate where their crowns are. Two to three inches is sufficient. Be careful, however, with plants such as garden phlox (P. paniculata) and the larger growing grasses (such as miscanthus), whose rigid stems can present a danger if you cut them at an angle rather than parallel with the ground. More than once we’ve stabbed ourselves during cleanup.
Fall is also the time to renew any faded plant labels. We usually bury most of the label, leaving a portion aboveground. If they’re too far out of the ground, wind, crows, frost heave, and errant visitors can scatter them; bury them completely, and you may never see them again.
Woody plants may need attention in the fall, but before you start wielding the loppers, familiarize yourself with each plant’s behavior with regard to bloom and foliage and branch growth, as well as with any idiosyncracies it might have. Maples and birches, for example, are best pruned either in the fall or after the first flush of summer foliage has hardened in mid- to late June. If pruned in late winter or spring, the plants will most likely bleed horribly, which is not only ugly but can also lead to infection. If pruned in late summer, they may put on a spurt of late growth that will be tender going into winter.
Evergreens should also get a look-over in the fall, especially in areas that experience heavy snowfall. Long, horizontal growth may be shortened to reduce the likelihood of snow and ice damage, but be sure to bone up on the plant in question first to make sure that your efforts won’t be counterproductive or harmful.
With certain stipulations, fall is a good time to mulch the border. One consideration is accessibility—if you’ve left most of the plants standing, you’ll probably want to wait until spring. Also, in mild, damp climates, mulch that’s applied in the fall can trap moisture, leaving certain plants more prone to rot or disease. If you’re worried that your mulch may hold excess water, try a lighter, fluffier material. Heavy barnyard manure is definitely going to retain more moisture than a finely ground product based on wood chips, let alone grit, gravel, or other nonabsorbent materials.
Another consideration is that summer warmth, when trapped by autumn mulch, can exacerbate frost heave in early winter, just when divisions and transplants are at their most vulnerable. It’s usually best to let the soil chill before mulching. However, there’s also a danger if mulch is applied to frozen ground in early spring, especially if the border contains lots of early-blooming bulbs—hearing the crunch of a tender growing point underfoot is never pleasant. There’s no easy answer to this question; you need to balance considerations of climate against the needs of your plants.
In a border with “hungry” soil, it’s advisable to apply a nutritive mulch every year for at least three years. Be careful, though—overfeeding will cause perennials to grow rampantly, which will mean more frequent dividing and staking. Furthermore, not all plants want to be grossly fed. Trees and shrubs, in particular, may react by producing abundant weak growth that is more prone to splitting and cracking when weighted down by rain, snow, or ice.
Opposite: If unsightly, dying foliage bothers you the way it bothers us, you’ll want to do a thorough fall border-grooming. Above left: On the other hand, if you’ve chosen large numbers of plants that look good even when dead, you can leave them standing. Above right: The effect of an early-winter frost can also be pleasing, but bear in mind that the border may well look sorrier come February.
It can be useful to add some “marker plants” to the border. Certain perennials with delicate growing points, such as herbaceous peonies and trilliums, leave no tell-tale stubble or remains, and hence are easily stepped on before they come into full growth. But if the location of their crowns is indicated by marker plants that either die down early or are low in habit (and tolerant of summer shade), then there’s much less chance that you’ll inadvertently crush a choice specimen. In our own gardens, we’ve chosen marker plants that have their main season of interest in the winter, such as snowdrops, Cyclamen coum, Primula vulgaris, and Primula juliae. Whatever plants you choose for this purpose, be sure that they won’t interfere with the growth of their main-season companion as it is coming into its own.
In an established border, plants may need to be divided and restrained, or you may wish to propagate them. In a climate where frost heave is frequent, this should probably be done sooner than the actual full cleanup. Irises, peonies, and other plants that come into flower during the first half of the growing season are usually best divided in early autumn. The soil should still be warm, and with adequate moisture there will be enough root growth to anchor the divisions before frost heave becomes too serious. If you’re in doubt about when to divide what, do some research.
If you’re planning on adding bulbs to your border, check to see how far various perennials have spread during the past growing season. A vigorous aster, for example, won’t be a good companion to a long-lived bulb that has a blunt growing tip, such as a hyacinth. Slow clumpers, such as Cimicifuga ramosa, often make the best neighbors, since they don’t need dividing very often and will cohabit with bulbs for years with little problem.
If you’re going to be planting bulbs, you might as well get creative. Smashing combinations can be created with spring-blooming bulbs and the emerging foliage of perennials, especially those with shocking new growth, such as Valeriana phu ‘Aurea’, Hosta fortunei ‘Albo-Picta’, and Iris pseudacorus ‘Variegata’.
Animals and insects can wreak havoc during the dormant season. In areas of heavy snowfall, the trunks of woody plants may be prone to girdling by tunneling rodents. If you suspect rodent activity, it’s wise to place wire mesh guards around the trunks of young trees and shrubs. Also, if you plan to mulch in the fall with a light, fluffy material, be sure to put the guards in place before you mulch—light mulches are easy for critters to tunnel through. Don’t forget to remove the guards in spring, or at least to allow for the new season’s growth.
In milder climates, slugs, snails, and aphids are but some of the pests that can build up to intolerable numbers. Using the mildest chemical forms of control, iron phosphate and insecticidal soaps, can help decrease these numbers.
If there’s any remaining cleanup, do it now—you’ll want to have a pleasing stage for the spring display to come.
Of course, this is also the time of year when fall plant catalogs arrive, and on a cold day nothing can be more pleasant than being tempted by new offerings. However, remember that you need to have room for the plants you’re tempted by. We’ve found it’s helpful to mark the plants you want, set the catalog aside for several weeks, and then revisit it. Reality checks aren’t easy, but, unless you have the luxuries of unlimited space and a bottomless pocketbook, they are necessary. H