Container plants can transform outdoor space

Adrian Higgins

THE WASHINGTON POST – King Louis XIV famously grew orange trees in the wooden boxes known as Versailles planters, but you don’t have to be rich, regal or into powdered wigs to enjoy the luxury of growing plants in pots.

From the smallest city balconies to expansive suburban backyards, containers and the plants they hold have the ability to transform any outdoor space and take the garden joyfully from summer to fall.

The container garden can be as exuberant or elegantly subdued as you like, and much of the creative fun is in matching the pot or planter with the plant effect you desire. The options are broad, and visits to the terraces of public gardens will offer plenty of inspiration.

WHY CONTAINERS

Whether you’re growing annuals, tropicals, herbs or anything else, there are many good reasons to turn to containers. Plants raised in pots expand the presence of the landscape and garden to the patios, terraces and walkways immediately around the home. You can create sculptural focal points where they’re needed and bring colour and texture into otherwise empty areas.

Container plantings also draw butterflies, hummingbirds and other pollinators, and they generally enliven the outdoor living space at a time when other areas of the garden have receded after spring.

For those in urban spaces, the container may be the only way to introduce eye-catching plants, including herbs and veggies, to your world. (If your piece of the outdoors is an elevated balcony, make sure containers are secured and remain within weight limits.)

Lastly, the right container, in size and form, can project a sculptural quality that gives a space an aura of elegance.

CONTAINER TYPES

Pots and planters are available in many materials and shapes, but a couple of principles apply to all of them. First, the larger the container, the less the stress on the plants, because soil moisture and temperatures will be more even. Second, the container must drain, unless you’re growing pond plants. And resist the urge to place a saucer beneath a pot; doing so will lead to wet soil and root rot.

Larger pots are harder to handle and are more expensive than smaller ones, but a single large pot or a grouping of three, say, will have a presence that a clutter of small pots lacks.

If you’re putting more than one plant in a pot, use a container at least 19 inches across, said Margaret Atwell, who creates the terrace containers at the US Botanic Garden.

Mass-produced terra-cotta pots are affordable and handsome enough. Plastic versions retain moisture longer, but you may feel as if the world already has enough plastic. Glazed clay pots can complement a colour scheme, if you’re planting with one in mind.

Other materials abound. Some containers and planters are wooden – the half barrel being the obvious example – and others are concrete or reconstituted stone. Some of the most stylish containers are made of a resin mix and resemble stone, lead or other natural materials.

The Victorians liked their cast-iron urns and pots, but beware of metal containers. In hot regions, such as the Mid-Atlantic, a metal container, especially a dark one, can get too toasty in a sunny location and cook the plants. One way to mitigate this is to line the container with bubble plastic. Another would be to place it in a shadier location and plant accordingly.

Another factor to watch is narrow necks. If the opening is smaller than the rest of the container, root growth will make it difficult to remove plants in autumn.

Mass merchandisers and independent garden centres are convenient sources of containers, and, of course, the Internet is a boundless emporium. (It can be difficult, though, to grasp the dimensions of a pot from an online image.) For high-end containers, you can spend several hundred dollars – or even more than a thousand – but, with care, they can last for many years.

Several national home-decor retailers, such as RH, Pottery Barn and West Elm, stock outdoor planters. In addition, antique, reproduction and contemporary containers are available from Pennoyer Newman, Detroit Garden Works and Seibert & Rice. Authentic Versailles planters handmade in France are available from AJF Design.

SOIL MIXES

Don’t use soil from the garden in pots; it’s too dense and will become saturated, which leads to root rot. Potting mixes typically contain peat moss; limestone to buffer the acidity of the peat moss; humus; and perlite. Harvesting sphagnum peat moss from bogs has become an environmental concern, and peat-free mixes are available. Or you can make your own mix with finished, screened compost, sharp sand and some garden loam. Some gardeners add fine pine-bark mulch and chicken grit.

The amount of potting mix needed grows exponentially with pot size, and larger pots can easily gobble up whole bags. Because seasonal plants don’t require particularly deep soil, you can save on potting-mix costs by filling the bottom third or half of a big container with something else. Chunks of plastic foam used to ship TVs and the like can be used (but not foam peanuts, which become a pain to extract when the pot is emptied). Atwell uses wood chips as a bottom filler. I like to use pea gravel topped with filter fabric, which stops soil from washing through. This renders the pots heavy (and secure), so do the soil work after you have placed the pot where you want it.

Leave an inch or so between the soil line and the rim of the container to allow for more efficient watering.

PLANT OPTIONS

All six of our featured summer annuals and perennials – elephant ear, coleus, lantana, calamint, rudbeckia and echinacea – have a place in the container garden.

If you’re going with annuals and tropicals, the formula of thriller, filler and spiller still holds – that is, an upright starring plant (thriller), a plant cascading over the lip (spiller) and something to occupy the rest (filler).

Atwell recommends going to a nursery and perusing the whole array of plants as candidates for the container combination. “Look at everything, even the houseplants, even vegetables and herbs, and look for things that have interesting leaves, colours, patterns and textures,” she said. “It could even be a shrub.” Some of the most appealing and enduring container plantings don’t lean too heavily on flower ornament.

Jennifer Williams of the Brooklyn Botanic Garden said she often has a colour palette in mind when putting together combos, and she limits the foliage and blooms to four or five colours. One theme might be lemons and limes, another silver and gold.

It helps to first know the light conditions of your container location. Partial shade gives plants some respite from the full-on afternoon sun (and reduces watering needs).

In constant shade, flower display will fall off, so go for foliage effect alone with such plants as ferns (hardy or tender), asparagus ferns, caladiums, philodendrons and coleus, to name a few. In thinking of colour, Atwell said, don’t forget that a combination can be in shades of green, including lime green.

Herbs are an obvious choice for containers, because most of them like hot summers on the dry side. They’re happier in free-draining containers than in garden beds, and they’ll still need regular watering.

With care, many vegetables will grow happily in containers and are surprisingly attractive. Some of my favourites are Swiss chard, parsley, trailing and bush tomatoes, peppers and eggplant (along with trailing nasturtium). In spring and fall, you can add various cool-season leafy greens, including mustard greens, lettuce, chervil, cilantro, arugula and kale. Such veggies also can be incorporated into traditional combinations.

Williams would add sorrel, lovage and strawberries to the list. She also likes to use basils and points out that the gardener doesn’t have to worry about them bolting in a pot. “It doesn’t have to be about the food. You can let your basil flower, and it’s going to bring butterflies and bees, and you can use it as a cut flower in your house,” she said.

Fruit bushes and trees are also grown in containers – the choices include citrus, pomegranate, blueberry, bananas and figs – but you’ll need a protected winter environment for most of those.

Another approach is to plant just one kind of annual, tropical or even perennial or ornamental grass in a container, which elegantly avoids some of the busyness of a traditional combo of annuals. Tender and half-hardy decorative salvias, such as Mexican bush sage, pineapple sage and little-leaf sage, make great container specimens all the way to October.

FEEDING AND CARE

What’s the price of all this instant and movable beauty? Watering. Most containers will need a deep drink daily during the hottest weeks of the year.

You know the pot has been thoroughly soaked when water drains from the bottom. Try to water the soil rather than the foliage, and do so before plants show any significant wilting.

Use a watering can or a soaker wand attached to the garden hose. The jet from a regular nozzle is too strong. I’ve seen setups with drip emitters and tubes; however, I wonder whether they deliver enough water, and besides, they make the container look as if it’s in intensive care.

Water your pots even when it rains. Containers are not sufficiently watered by nature, even in summer deluges. Your finger is the best tool for gauging soil moisture. Your eye is the next best tool; look for leaves that are flagging.