Think your garden’s ready to rest now that autumn’s here? Think again

IN EARLY JULY, much of Atlantic Canada had an unwelcome visitor: Arthur, a post-tropical storm that left his calling card in a swath across the region. Fortunately, there wasn’t as much damage to property as say, Hurricane Juan, but because trees were in full leaf, they took a beating. Many properties had branches or trees break off and land on gardens, lawns and, in some cases, the roofs of buildings.

Shortly after that, I started receiving emails from people wondering if they could plant in July. The short answer: Of course! And, for those of you wondering, you can keep right on planting now in September and into October. I have a few tips to help ensure a successful transplanting, and if you follow those, you should have success in adding a late-season show to your garden’s lineup.

Late summer and early autumn are great times to plant perennials, trees and shrubs. The soil temperatures are warm, as are the days—though not as hot as during high summer—and nights are cooler.

There’s usually more soil moisture available since there’s more precipitation (though hopefully not torrential rains from hurricanes), lessening the need to water as often.

The other advantage of planting in late season is that you can look at your garden’s colour palette, determine what it’s missing for late-season colour and add plants accordingly. Then you’ll be able to enjoy your new treasures as the season winds down and you get ready for bulb planting, which can be done, as we’ve discussed before, right up until the ground freezes hard, around Christmas or New Year’s.

Normally, you shouldn’t bother planting annuals in late summer unless you can get late-blooming varieties that have been started locally over the past few weeks and aren’t completely root-bound. If you try planting from seed, you’re unlikely to get flowers before frost. What you can do, if there’s a local nursery selling them, is buy large containers of late season annuals—dwarf sunflowers, zinnias, marigolds, celosia, fall chrysanthemums, grown in midsummer for just such a purpose—one last hurrah of colour.

If you’ve been deadheading your perennials faithfully over the summer, some will keep flowering until there’s a hard frost, or they’ll have a rebloom that isn’t as profuse as the first, but still lovely. Some daylilies, for example, are rebloomers and will keep flowering until frost or snow stops them.

Choosing healthy plants

Often you can get great sales on late-season supplies of shrubs, trees and perennials, as not all nurseries have a lot of space for winter storage of leftover stock. You’ll often find the plant equivalent of scratch-and-dent sales for further reductions, but be careful about buying damaged plants.

If you’re a skillful gardener and know what you’re looking at and what to do about a particular problem, you can probably bring around a tree with a broken limb or a perennial in need of transplanting, but you need to be able to judge whether a plant is redeemable or should be made into compost.

There are a few things you can look for. Make sure that what is growing in the pot is actually the species you want. I’ve seen “sale areas” where there are weeds growing in pots, the actual perennial having died.

Leaves should be clean and free of obvious blight problems (mould, spots, dying foliage).

If some leaves are chewed or tattered, check for insect infestation. It could be that leaf damage is due to wind or to a pot being knocked over, or there may have been leaf-cutter bees taking pieces away for their nests. None of these things will be fatal to a plant. Look for clusters of aphids on tender new growth or on flower buds (for example, on roses).

If possible, check the rootball of the plant. Roots growing out the bottom of a pot is not the sign of a healthy plant, but sometimes the plant outgrows its pot within a summer growing season and just needs to be planted out or transplanted to the next size pot.

Slide the plant carefully out of the pot and look at the roots, which should be firm, white or yellowish in colour, and not completely filling the pot. If roots are brown, mushy, smelly or black, leave the plant there—it might not look dead yet but it’s well on its way to that great greenhouse in the sky. If the plant is root-bound, and you really want it, you can take it home and fix it by teasing the root ball before planting. More on that shortly.

Trees and shrubs: avoid trees with two leaders (two branches that are trying to be the main branch of the tree) as this can lead to a brittle tree prone to breakage unless pruned properly.

If limbs have been broken off, check to make sure they’ve been pruned cleanly as close to the trunk or to another branch as possible. There’s no need for “wound dressing” to be painted over such breaks: the tree or shrub will heal naturally over time. If the broken area is decaying and spreading towards the main branch, leave the plant there.

Caring for your new treasures

If possible, put your new plants in a shaded area until you’re ready to plant. If you bring them home on a hot summer’s afternoon, don’t plant right away—give them a drink and wait for cooler temperatures.

The best transplanting time is right after or during a rain, or on an overcast day when there’s less chance of heat stress, especially if you’ve had to tease the rootball.

You can tell if a plant is rootbound or potbound—its roots will all be growing in a thick mat, round and round, within the confines of the pot. Teasing the roots stops them from growing round in a circle, and not spreading out and down like they should.

Some of those trees and shrubs that were blown over by Arthur had roots growing in a tight circle, exactly as they had been when planted, whether five or 25 years ago. To tease the roots, use a sharp knife, secateurs or scissors to cut into the matted roots, breaking them. Don’t worry. Once planted, those roots will stretch out in all directions, and the plant will be healthier for such treatment.

One reason that plants, especially shrubs and trees, often don’t survive their first season in a new garden is that they haven’t been watered adequately. Growing plants need water, lots of it, especially when they are first put into the ground after having lived in a container for months or even years.

Just because some perennials and grasses are listed as “drought tolerant once established,” that doesn’t mean you plant and leave them to nature’s watering. Water well, not often, is the mantra of success for newly planted specimens, since it’s better to water deeply once a week than to water sparsely every day.

You want the roots to grow down deep into the soil, helping establish the plant so that in future years it can deal with less water, and can withstand winds without blowing over.

One final reminder

You can prepare the ideal site, bring home a healthy-looking plant, plant it properly and care for it correctly, and still sometimes it will die. It happens. It might not be as hardy as its tag says, or it might have had some pest attack it before or after you brought it home, or a late spring cold snap might take it out after it survived all winter. It really does happen to every gardener, sometimes yearly (I’m waving my hand, here!). Please don’t be discouraged—you can always plant something new.