Perennials for Sandy Soils: A Toronto Master Gardeners Guide

Perennials such as blue spirea (Caryopteris) – shown here in two foliage variations – and purple Russian sage (Perovskia) can make dramatic additions to the well-drained, sandy garden. Photo: Helen Battersby

Perennials are plants that renew themselves each year from their hardy roots. Although there are woody perennials, such as trees and shrubs, the plants most people refer to as perennials are herbaceous plants that die back to the ground at the end of the growing season and re-emerge each spring to grow and bloom.

Perennials are playing an increasing role in our gardens, often taking over from mass plantings of annuals in both private gardens and public spaces. They offer excellent value as you only have to plant them once for years of enjoyment. Perennials provide an amazing variety of both flowers and foliage. There is a range of sizes to suit any site. Perennial plants add drama to the garden in every season. From early spring to late fall they continually change the appearance of the garden as different plants come into bloom. Those with decorative seed heads or a lasting framework continue to provide interest into winter.

Uses

A current trend in gardening can best be described as the “Mixed Border.” All varieties of plants, that is, trees, shrubs, evergreens, flowering bulbs, annuals, grasses, wildflowers, herbs and perennials are combined in one border to create a pleasing design. In this way, colour and interest is provided for all four seasons, including our Canadian winter. Plan to include spring blooming perennials with spring bulbs and flowering shrubs, and fall blooming perennials with ornamental grasses.

Many of the perennials for sandy soil also make a great addition to mixed container plantings. If you plan to attempt to over-winter the perennial in the container, then select plants at least two zones hardier than ours (Toronto is zone 6).

Characteristics of Perennials for Sandy Soils

Sandy soils can be hot, dry and poor in nutrients. Sandy soils are fast draining and, therefore, dry out quickly. Most plants do not tolerate wet feet, so this aspect is a plus for many plants. However, it can also mean that sandy soils can be too dry for some plants. The key to success is to plant perennials which can tolerate or even thrive in these conditions. Ideal candidates for sandy soils are plants, such as Achillea (Yarrow) that prefer poor, dry soils and are heat tolerant.

Although most of the metro Toronto area has clay soils (nutrient rich and slow draining), sandy soils are found in the Beach, East York, Etobicoke and in cottage country. Growing drought tolerant plants is a good strategy for areas where watering of gardens may be restricted or where gardens may only be watered on weekends, as in cottage country.

Most of the perennials that thrive in hot dry sandy situations require full sun, which means a minimum of six hours of direct late-morning or afternoon sun. Plants that will tolerate dry shade, or semi shade conditions, have also been included below.

Considerations Related To Choice

Within a genus (family) of plants it is important to realize that not all species or cultivars have the same cultural requirements. For example, although most Artemisias are heat and drought tolerant, Artemisia lactiflora (White Mugwort) prefers a moist site. Before choosing other cultivars from the same genus, check the plant label for soil and moisture requirements or consult one of the references listed below.

General Care and Maintenance

Cultural Conditions

It is important to choose plants that match your growing conditions to minimize maintenance and maximize plant performance. Although some perennials thrive under hot, dry conditions, keep in mind that most perennials do best with one inch of water per week. Many perennials do fine in average, well-drained soil. But improving the soil before planting will ensure that the perennials perform well for years in the garden. It will also allow for a wider variety of plant choices.

Before planting new perennials, you should amend dry sandy soils with 10 to 15 cm of organic material, such as moistened peat moss, composted manure, compost, or leaf mould. This will add nutrients and improve the ability of the soil to hold moisture. When adding organic material, do not dig the amendment into the soil. This will disturb the soil profile, established over many years by every-present soil microorganisms. Instead, top dress the planting area with the organic material, and let the worms and other tiny creatures do their work. Slow-release organic fertilizers, like bone or blood meal, or granular fertilizers, are best added when soils are being prepared. Remove all weeds before planting.

Using a product containing mycorrhizal fungi (a fungus that occurs naturally in the soil) at planting time, will enhance the development of the roots, reduce transplant shock, and result in a sturdier healthier plant.

A 2-3” layer of organic mulch will keep the soil cool and moist, reduce water requirements and lessen weed germination. As well, it improves soil structure and feeds the plants when it breaks down. Shredded bark, compost, and pine needles make good mulches.

Newly planted perennials, even those that are drought tolerant once established, need to be watered at planting time. Then, water every week for the first two weeks and during periods of drought. For the first year, all perennials will benefit from regular watering so that they can become successfully established. Most borders thrive best with a minimum of one inch of water per week. Monitor and pull out weeds as they germinate and while still young to prevent them from setting seed.

Deadhead perennials to prolong bloom or, alternatively, allow attractive seed heads to stand over the winter. Tidy up the plants in the fall by removing unsightly foliage. During spring cleanup flowers stalks should be cut just above the ground.

Pests and Diseases

Monitor your plants regularly for potential problems. For aphids and spider mites, spray with water. Always dispose of diseased foliage in the garbage, not the compost pile. Look for perennials that are noted for pest and disease resistance.

Recommended Species/varieties/cultivars

Full Sun
  • Achillea millefolium “Paprika” or “Terracotta” (Common Yarrow) – hardy to Zone 2; 18 – 30” tall; September bloom
  • Achillea millefolium “Moonshine” (Common Yarrow) – hardy to Zone 3; 18 – 24” tall; October bloom
  • Antennaria dioica “Rubra” (Pink Pussy Toes) – hardy to Zone 1; 4 – 6” tall; June bloom; evergreen
  • Anthemis tinctoria “Sauce Hollandaise” and “Wargrave Variety” (Golden Marguerite Daisy) – hardy to Zone 2; 12 – 18” tall; August bloom
  • Arabis alpina subsp. Caucasica “Snowcap” or “Rosea” (Rock Cress) – hardy to Zone 3; 6 – 8” tall; June bloom; evergreen
  • Armeria maritima “Dusseldorf Pride” (Common Thrift) – hardy to Zone 2; 4 – 6” tall; June bloom; evergreen
  • Artemisia “Huntingdon” and “Powis Castle” (Wormwood) – hardy to Zone 5; 2 – 3’ fall
  • Asclepias tuberosa (Butterfly Milkweed) – hardy to Zone 4; 2 – 3” tall; August bloom
  • Aurinia Saxatilis “Citrina” (Perennial Alyssum) – hardy to Zone 3; 8 – 12” tall; June bloom
  • Baptisia australis “Purple Smoke” (False Indigo) – hardy to Zone 4; 3 – 4’ tall; June bloom
  • Buddleia davidii “Potter’s Purple” and “White “Profusion” (Butterfly Bush) – hardy to Zone 5; 4 – 8’ tall; October bloom
  • Carlina acaulis subsp. simplex bronze form (Friendly Thistle) – hardy to Zone 3; 12 – 18” tall; July bloom
  • Caryopteris x clandonensis “Worcester Gold” and “Longwood Blue” (Blue Spirea) – hardy to Zone 5; 2 – 3’ tall; October bloom
  • Coreopsis verticillata “Moonbeam” (Thread-leaved Coreopsis) – hardy to Zone 4; 12 – 18” tall; September bloom
  • Delospersma nubigenum (Yellow Ice Plant) – hardy to Zone 3; 2 – 4” tall; June bloom; evergreen
  • Dianthus x allwoodii “Bath’s Pink” and “Mountain Mist” (Border Pinks) – hardy to Zone 3; 8 – 12” tall; July bloom; evergreen
  • Echinacea purpurea “White Swan” and “Magnus” (Coneflower) – hardy to Zone 3; 30 – 36” tall; October bloom
  • Eryngium planum “Sapphire Blue” (Blue Sea Holly) – hardy to Zone 4; 24 – 30” tall; August bloom
  • Gallardia x grandiflora “Mandarin” or “Goblin” (Blanket Flower) – hardy to Zone 2; 20 – 24” tall; September bloom
  • Lavandula augustifolia “Munstead” (Lavender) – hardy to Zone 4; 12 – 16” tall; August bloom
  • Liatris spicata “Floristan Violet” or Florisan White” (Blazing Star) – hardy to Zone 2; 30 – 36” tall; September bloom
  • Limonium latifolium “Sea Lavender / Statice) – hardy to Zone 2; 24 – 30” tall; August bloom
  • Linum perenne “Blue Sapphire” (Blue Flax) – hardy to Zone 2; 10 – 13” tall; August bloom
  • Lychnis coronaria “Angel’s Blush” (Rose Campion) – hardy to Zone 3; 2 – 3’ tall; August bloom
  • Nepeta racemosa “Walker’s Low” or Nepeta “Dropmore Blue” (Catmint) – hardy to Zone 2; 12 – 16” tall; September bloom
  • Oenothera fremontii “Lemon Silver” (Evening Primrose) – hardy to Zone 4; 4 – 6” tall; August bloom
  • Origanum laevigatum “Herrenhausen” (Ornamental Oregano) – hardy to Zone 4; 1 – 2’ tall; October bloom
  • Papaver nudicaule “Flamenco” or “Champagne Bubbles” (Iceland Poppy) – hardy to Zone 2; 12 – 18” tall; October bloom
  • Penstemon barbatus “Elfin Pink” or Prairie Dust” (Beard-tongue) – hardy to Zone 3; 12 – 24” tall; August bloom
  • Perovskia atriplicifolia (Russian Sage) – hardy to Zone 4; 3 – 5’ tall; October bloom
  • Phlomis tubersoa “Amazone” (Sage-leaved Mullein) – hardy to Zone 2; 3 – 4’ tall; August bloom
  • Phlomis fruticosa (Jerusalem Sage) – hardy to Zone 5; 2 – 4’ tall; July bloom
  • Phlox douglasii “Crackerjack” or “Rose Cushion” (Moss Phlox) – hardy to Zone 2; 2 – 4” tall; May bloom; evergreen
  • Potentilla thurberi “Monarch’s Velvet” (Red Cinquefoil) – hardy to Zone 4; 12 – 16” tall; September bloom
  • Ratibida columnifera (Prairie Coneflower) – hardy to Zone 2; 2 – 3’ tall; September bloom
  • Salvia x sylvestris “Caradonna” or “Mainacht” (syn. “May Night”) (Perennial Sage) – hardy to Zone 3; 18 – 20” tall; July bloom
  • Salvia verticillata “Purple Rain” (Whorled Sage) – hardy to Zone 3; 16 – 18” tall; August bloom
  • Santolina chamaecyparissus (Cotton Lavender) – hardy to Zone 6; 12 – 18” tall; July bloom; evergreen
  • Scabiosa columbaria “Butterfly Blue” (Pincushion Flower) – hardy to Zone 4; 12 – 18” tall; October bloom
  • Tanacetum niveum “Jackpot” (Snow Daisy) – hardy to Zone 3; 12 – 18” tall; October bloom
  • Thymus “Doone Valley” (Thyme) – hardy to Zone 4; 2 – 4” tall; August bloom; evergreen
  • Verbascum “Helen Johnson” (Mullein) – hardy to Zone 3; 30 – 36” tall; August bloom
  • Veronica prostrata “Aztec Gold” or “Trehane” (Speedwell) – hardy to Zone 4; 4 – 6” tall; June bloom
  • Veronica whitleyi (Whitley’s Speedwell) – hardy to Zone 3; 2 – 4” tall; June bloom; evergreen
 Part Sun – Part Shade
  • Aster divaricatus (White Wood Aster) – hardy to Zone 3; 18 – 36” tall; October bloom
  • Eupatorium rugosum “Chocolate” (Boneset) – hardy to Zone 5; 3 – 4’ tall; October bloom
  • Euphorbia myrsinites (Donkey Tail Spurge) – hardy to Zone 5; 6 – 8” tall; June bloom; evergreen
  • Eurphorbia polychroma (Cushion Spurge) – hardy to Zone 2; 12 – 18” tall; June bloom
  • Gaura lindheimeri “Whirling Butterflies” or “Siskiyou Pink” (Butterfly Gaura) – hardy to Zone 5; 3 – 4’ tall; October bloom
  • Hermerocallis “Happy Returns” or “Apricot Sparkles” (Daylily) – hardy to Zone 2; 12 – 16” tall; September bloom
  • Iberis sempervirens “Snowflake” (Candytuft) – hardy to Zone 3; 8 – 10” tall; June bloom
  • Persicaria affinis “Dimity” (Dwarf Fleeceflower) – hardy to Zone 3; 6 – 8” tall; August bloom
  • Pulsatilla vulgaris “Papageno” (Pasque Flower) – hardy to Zone 2; 6 – 12” tall; May bloom
  • Sedum (Herbstfreude Group) “Herbstrfeude” (syn. “Autumn Joy”) or “Purple Emperor” (Stonecrop) – hardy to Zone 2; 1 – 2’ tall; October bloom
  • Sempervivum “Purple Beauty” or “Thayne” (Hens and Chickens) – hardy to Zone 1; 2 – 4” tall; August bloom; evergreen
  • Stachys byzantina “Helene von Stein” or “Primrose Heron” (Lamb’s Ears) – hardy to Zone 3; 12 – 18” tall; evergreen
  • Symphytum ibericum (Yellow-flowered Comfrey) – hardy to Zone 4; 8 – 12” tall; July bloom
  • Teucrium chamaedrys “Summer Sunshine” (Germander) – hardy to Zone 4; 6 – 8” tall; August bloom; evergreen
Part Shade – Shade
  • Lamiastrum galeobdolon “Hermann’s Pride” (False Lamium) – hardy to Zone 2; 10 – 12” tall; June bloom; evergreen
  • Pachysandra terminalis “Green Sheen” (Japanese Spurge) – hardy to Zone 3; 6 – 8” tall; May bloom; evergreen
  • Vinca minor “Atropurpurea”, “Illumination”, or “Sterling Silver” (Periwinkle) – hardy to Zone 3; 4 – 6” tall; May bloom; evergreen
  • Waldsteinia ternata (Barren Strawberry) – hardy to Zone 3; 4 – 6” tall; April bloom; evergreen

References

Valleau, John. Perennial Gardening Guide. Abbotsford, British Columbia: Valleybrook International Ventures Inc., 2003.

DiSabato-Aust, Tracy. The Well-Tended Perennial Garden, Planting and Pruning Techniques. Portland, Oregon: Timber Press,1998.

Heritage Perennials  https://www.perennials.com

Date revised: January 2012

For printable version, click:  Perennials for Sandy Soil – A Toronto Master Gardeners Guide

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