May 30, 2013
Xeriscaping: Drought resistant gardening

Sempervivum makes a super filler for strawberry jars. This jar has been preserved for several seasons by burying it in a trench for the winter months.
As the invited guest speaker, I sat back to enjoy a lively discussion on public plantings at a rural horticultural society meeting. The efforts of the volunteers were to be commended. Hundreds of schoolchildren were organized into teams, directed by the enthusiastic members of this society. Boulevards, public gardens and the entrances to a new nature trail had been planted with drought tolerant perennials, grasses and shrubs, in a one-day blitz.

Tonight they were arranging for the maintenance and watering of these beds, at least for this season, until they became established and somewhat self-sufficient. Without accessible water nearby, these rural volunteers were committed to driving long distances and lugging water from their homes, to ensure the success of their projects. I was impressed by their dedication — larger, urban groups often beg unsuccessfully for volunteers (where the gardens are much closer to home).

Water is a precious resource. We often hear of the plight of the drought stricken American states such as California and Washington where xeriscaping (gardening with drought-tolerant plants) has been elevated to both a science and an art form.

Here in Niagara we have become aware of the dangerously low water levels of our surrounding lakes and rivers. We must all become more aware of conserving water, particularly after it has been treated for human consumption. Barring paving the lawn and painting it green (my father-in-law's favourite plan), what can we do? A few simple practices can help the home gardener maintain a beautiful garden while saving precious water, time and effort.

First, install a rain-barrel. Last summer, we installed a large plastic barrel below one of the downspouts on the back of our house. Surprisingly, it was filled to capacity after one healthy rainfall. Fitted with a screen on top (to keep out debris), a child and pet-proof barrier (for safety) and a hose for the convenient filling of watering cans, it kept a constant supply of chemical-free, warm water at hand for watering containers, hanging baskets and newly planted seedlings. As an added bonus, the grass below the downspout is no longer waterlogged for days after a storm.

Second, mulch the garden containers. A layer of shredded bark, wood chips, cocoa beans or even grass clippings will help to conserve precious moisture in the soil.

Have doubts? Try this simple test. Cover a small patch of garden with a layer of mulch. Leave a patch of garden by its side open to the elements. After a week, pull back the mulch and push your finger into the soil below. In all likelihood, you cannot push your finger into the non-mulched soil at all. See how much moisture is retained in the mulched side? The soil remains cooler under a mulch cover, as well.

A planting of Salvia 'Victoria' and Heliotropium 'Marine Lemoine Strain' proved to be very drought resistant in the author's garden.

Achillea adds colour to a dry garden.

Four bamboo canes were used to fashion this simple trellis, which is set in a clay container that is painted to look like old stone. Helichrysum petiolare is trained up the trellis, creating an unusual backdrop for this display of xeriscape containers, ideal for a sunny deck or balcony.
Mulches will keep the weed population to a minimum. The weeds that do appear can usually be pulled fairly easily, since their roots are not cemented in the dry soil. Weekly hoeing and cultivating are all but eliminated. When it rains, the valuable water will more easily percolate into the soft mulch cover (rather than quickly run off the hardened soil crust). It will also prevent mud from splashing up and disfiguring your favourite perennials just as they are at their peak. Ground covers such as sweet woodruff, perennial geraniums, ajuga and thyme (to name but a few) can act as living mulches once established in the garden. I have found a combination of both living and dry mulches to be very effective (and beautiful) in my own garden.

Last, but not least, plant suitable annuals and perennials for your site. The importance of this simple principle cannot be stressed enough. Choose drought-tolerant plants whenever possible, particularly if watering will be difficult or improbable. For example, do not set water and shade loving impatiens in the full sun, leaving them to bake. Without dedicated watering they will suffer terribly. Rather, try planting portulacas (equally colourful plants that love hot, dry conditions) instead. They will reward you with tropical, hot colours with very little (if any) watering required.

The same holds true for your hanging baskets and planters. Choose the plants that will suit the location you have in mind. How many homeowners have come home to find their lush hanging baskets, filled with sunny impatiens or tuberous begonias shriveled up past recognition after leaving them in the care of an non-gardening teenager or neighbour while away for a couple of days.

For a carefree and drought tolerant container, try the following combination of plants in a strawberry jar (suitable for a hot, sunny location): Sempervivum (hens and chicks) 'Sanford Hybrids' and 'Cobwebs' (great for kids), Santolina and Armeria maritima (thrift) 'Splendens'. Plant one plant in each of the side planting holes of the strawberry jar. Top it off with Festuca glauca (blue fescue) 'Elijah Blue'. This jar will require watering weekly vs. daily (the typical watering required of most strawberry jars.

Other suitable plants for dry containers include Dianthus gratianopolitanus (cheddar pinks); Thymus x citriodorus (lemon thyme) 'Gold Edge' and 'Silver Queen' are particularly effective; Echiveria; and Acaena caesiiglauca (sheepburr), with its delicately serrated blue leaves.

Xeriscaping at work
I was recently presented with a challenge. Could I design a colourful, low maintenance garden for the front raised bed at the public library? Sounds fairly easy, but there were a few catches (as usual).

The garden consisted of a raised bed, 18-inches deep by 24-feet long, standing about two feet above a busy sidewalk. The wide wooden surround was naturally used as makeshift seating for passersby.

Facing west, the garden sat in full sun for the better part of the day. To complicate matters, the hoses used by the library to irrigate the surrounding gardens did not reach this bed. Consequently, it was watered by hand once a week, relying on rainfall for any additional water. Every spring the garden would start out with a fresh blanket of impetuously chosen annuals. Given the hot, dry summers we have recently experienced, the planting languished by mid-summer. It was doomed to fail from the outset — the garden had not been planted with these desert-like conditions in mind.

With water meters being currently being installed locally, this garden could be a mini-showcase for the benefits of xeriscaping (gardening with drought-resistant plants) for visitors to the library.

My plan was to create a memorable gathering spot for visitors, by selecting a pleasing combination of colourful, scented, drought tolerant plants. They should look good for a long period, and require very little maintenance over and above the weekly watering. Last, but not least, there was the $100 budget to consider.

The plan
To create fountain-like anchors of sturdy foliage, three Hemerocallis 'Stella d'Oro' (daylilies) were planted equidistantly along the length of the bed. These golden daylilies are routinely included in public gardens for a good reason: they bloom almost non-stop from May to October (later in mild autumns). These dwarf daylilies average 30-45 cm (12 to 18 inches) tall and spread to a comfortable clump about 45 cm (18 inches) wide. They will not bully any of the other perennials for space.

This created four large planting sections to be filled. Starting at the northern end of the garden, a group of five Gaillardia x grandiflora 'Dwarf Goblin' (blanket flower) were planted. This under-used perennial blooms almost continuously in my own garden from early June until it is blanketed by snow. The brightly coloured, daisy-like flowers have red petals, brushed with yellow tips. Their compact habit (12-inches tall) and blanketing form make them well suited to this raised bed. Left to their own devices, they will bloom their hearts out all summer long. An occasional trimming of seed heads refreshes the plants, but is not required for continuous blooming.

Achillea 'Summer Pastels' (yarrow) was chosen to fill the next section. This is a seed grown mix of various yarrows, in a charming pastel mix of pink, salmon, lemon and creamy white. Yarrows are well suited to hot, dry locations and tolerate poor soils well. This compact variety averages 45-60 cm (18 to 24 inches) tall, with a spread of 60 cm (24 inches). This All American Award winner blooms from June to September.

Shades of blue were introduced with Salvia nemerosa 'May Night', another award winning selection (1997 Perennial Plant of the Year). Low mats of sturdy, grey-green foliage support dense spikes of deep violet-blue flowers. These showy plants average 18 to 24 inches in both height and eventual spread. Salvias are well suited to dry, sunny gardens. They are fairly drought tolerant once established. Catalogues suggest they will bloom from June to July. In my own garden, I have found them to be very tidy, bushy plants that cover the soil well (keeping weeds to a minimum). Given a good haircut after the first flush of bloom was over in late July, they responded with fresh foliage and bloom within a few short weeks. This plant remained tidy and colourful well into late fall.

The final quarter of the garden (the sunniest, and driest section) was filled with Lavandula angustifolia 'Blue Cushion' (lavender). Lavender originates in the Mediterranean region and prefers a sunny, well-drained site. This dwarf variety, averaging 40 cm (16 inches) tall, will offer memorable scent to visitors to the garden. The deep blue spikes of flowers appear over a long season. A light shearing in August will encourage a second, long-lasting flush of bloom by early September. Even out of bloom, the grey-green, needle-like leaves are fragrant and tidy looking. To prepare for planting a dry garden, I would suggest working some organic material such as compost or well-rotted manure into the garden soil. This will help to retain moisture, as well as nourish the young plants. The young plants should be deeply watered at planting time. A mulch cover of wood chips will help keep the weeds to a minimum. It will also help to retain valuable moisture while the root systems become established.

Theresa M. Forte is a garden consultant specializing in perennial borders, based in Niagara Falls, Ont.