Ten low-maintenance perennials

The plants suggested here are hardy, easy to grow, beautiful and very rarely have insect or disease problems. However, they are not native to the Ottawa area. Enjoy them in your garden, but please do not let them invade our natural areas! Please visit our native plants page for other options.

Achillea filipendulina (Asteraceae or Compositae)

Fern-leaf Yarrow

Achillea filipendulin

Achillea filipendulina

These clump-forming Yarrows bloom in early summer. The leaves are fern-like and aromatic. The flowers form flat-topped heads normally in shades of yellow though there are some cultivars that are pink, peach or red. Cultivars vary in height from a few inches to five feet tall and are used in perennial borders and meadows. After they bloom, cut the stems down to the ground.

  • Grow them in a sunny spot in evenly moist, fertile soil.
  • They do not need fertilizing, instead mulch annually with compost to maintain soil moisture and fertility.
  • They may get powdery mildew disease (August usually) when grown in poor, dry soil.
  • Divide the clumps every few years otherwise they become too large

Artemisia sp. (Asteraceae or Compositae)

Artemisia, Wormwood, Silver-Lady Lavender, Silver or White Sage

Artemisia sp.

Artemisia sp.

Artemisias are easy to grow in a hot, dry, sandy location and like many heat and drought-tolerant plants most have silver-grey foliage (fernlike, finely cut, silvery-white leaves with a hairy coating covering the leaf surface). The small, inconspicuous flowers are wind pollinated. There are many cultivars that differ in height, intensity of silver colour and leaf form. There are many species in cultivation, including Absinth, and the culinary herb Tarragon. Artemisia schmidtiana 'Silver Mound' is the most popular one used in Ottawa, it forms a 30 cm (12") x 30 - 45cm (12-18") mound, used as an edging plant in the border.

The leaf colour helps to tie the border together, adds an attractive contrast to dark green plants and, compliments pink, red, bronze and blue plants in the garden. They are also used in large mass plantings

  • Needs full sun to keep the colour strong and the growth sturdy.
  • Grows readily in any soil that is not wet, but prefers a dry, sandy, soil.
  • Should not be fertilized as plants become more greenish and spread too rapidly.
  • Regular division in spring or early September helps keep the spreading plants in check.
  • Cut 'Silver mound' back to 5cm (2") when it begins to bloom in mid to late June otherwise it flops open.

Astilbe (Saxifragaceae)

Astilbe

Astilbe

Astilbe

Astilbes originate in China and Japan but there has been a great deal of hybridization since the 1920's. Astilbes are considered the Queen of Flowers for moist shade, they are very low maintenance and free from problems. They produce dense, weed-proof groundcover and attractive flowers. Spike-like or soft, feathery, plume flowers rise above lacy dark green leaves; the many cultivars provide a long blooming time. Choose plants by size, flower colour and shape, and blooming time.

A. x arendsii: blooms from June- August, heights range from 55 - 100cm ( 22" - 3') flowers are red, pink, cream, white or lilac,

A. chinesis: this ground covering Astilbe blooms August - Sepember, height is 30 cm (12"), flowers are pink, salmon, lavender, purple, and magenta.

A. glaberrima saxatilis: a rockgarden plant at 10 - 20 cm (4 - 8"), blooming in July - August, shell-pink flowers

  • Partial shade in ordinary moist soil - full sun in very moist soil
  • Fertile, evenly and continuously moist soil
  • Top-dress with well-rotted manure/compost (2.5 - 5 cm) every fall
  • Divides easily in spring, as the new growth appears, plants can be lifted and divided or moved even in flower (if they are well watered)

Echinacea purpurea (Asteraceae or Compositae)

Purple Coneflower

Echinacea purpurea

Echinacea purpurea

This plant, native to the eastern United States, grows in grassy areas and open woodland meadows. The herbal remedy Echinacea comes from E. angustifolia. Flowers bloom above the rough, course leaves, which form a dense clump. The daisy flower head has a prominent hard, bristly, brown cone surrounded by drooping purple-pink petals. Echinaceas bloom from July - September. Purple Coneflower is an important plant for the summer border and for naturalizing meadows and wild-gardens. It grows to 75 - 120 cm (30 - 48 ") tall.

Rudbeckia, Black-eyed Susans, Cone-flower or Gloriosa Daisy, are similar to Echinacea in form, and requirements except that the bloom is bright yellow instead of purple.

  • Full sun
  • Ordinary well-drained garden soil, drought-tolerant
  • No fertilizer needed
  • Staking is needed in very rich, moist soils
  • Deadhead old flowers, seed heads can be use in dry floral arrangements.
  • Divide the clumps in spring. Seeds germinate easily and grow quickly.

Euphorbia polychroma (or E. epithymoides) (Crassulaceae)

Cushion Spurge

Euphorbia polychroma

Euphorbia polychroma

It is in the same family as Poinsettia and in fact it is the coloured bracts that give the plant its bright greenish-yellow colour in late spring (in Ottawa when the tulips bloom). In the spring it grows rapidly into a neat mound about 30 - 45 cm (12 - 18"), high having smooth, 5 cm (2") long leaves. The stems grow a little longer after the flowers fade forming a green mound, which turns red in the fall. All spurges produce a milky sap from broken leaves or stems, which may be irritating to the skin. Interplant it with spring flowering bulbs and perennials, at the base of a rock garden or with shrubs. Other spurges grown in Ottawa are:

E. griffithii: 50 - 90 cm (20 - 36") flame-orange bracts turn red in fall.

E.myrsinites: a succulent, prostrate, 15 - 20 cm (6 - 8"), blue leafed, evergreen rock garden plant with yellow coloured bracts in spring.

  • Full sun
  • Well-drained to dry soil, very drought-tolerant
  • Avoid fertilizing otherwise plants become floppy
  • Careful division in early spring (try to avoid damaging the fleshy roots)

Ornamental Grasses (Poaceae or Graminae)

Ornamental Grasses

Ornamental Grasses

The grass family contains about 6,000 species. The cereal crops are Grasses. They are highly evolved, wind-pollinated plants used for their long, thin foliage (may be brightly coloured) and upright form. The look and sound when they blow in the wind is very appealing. In the late summer they have feathery flowers at the top of the stems, which remain for months. Grasses range from 15 cm - 4 m (6" - 4 yd.) tall. Depending on size they can be specimen plants, container plants, groundcovers, mass planted or accents in the garden. Control their width to about 2/3 height. Clump forming grasses are not invasive. Grasses create a casual garden style, having full sensory impact in late summer and fall. .

  • Full sun
  • Ordinary garden soil. Most species are tolerant of dry soil but some are adapted to wet soil.
  • Does not need fertilizer
  • If it is grown for winter effect, cut them down in very early spring before new growth starts. Cut other grasses in late fall.
  • Best to divide in the spring just as the new growth starts, but many grasses can be divided in early September.
  • Hardy to Zones 3 - 5 (cultivar dependant)

Invasive Grasses- Do not plant

  • Arundo donax: Giant Reed
  • Bromus inermis 'Skinner's Gold"
  • Elymus racemosus (Leymus): Lime Grass
  • Glyceria maxima 'Variegata": Manna Grass
  • Miscanthus sacchariflorus 'Robustus': Giant Silver Grass
  • Phalaris arundinacea: Ribbon Grass
  • Spartina pectinata 'Aureo-marginata': Cord Grass

North American Grasses

  • Andropogon gerardii, A. scoparius: Blue Stem Grass (rare natives in the Ottawa area)
  • Bouteloua gracilis: Mosquito Grass
  • Carex grayii, C. muskingumensis: Sedge (C. grayii is native to Ottawa)
  • Chasmanthium latifolium: Sea Oats
  • Panicum virgatum: Switch Grass
  • Stipa tenuissima: Feather Grass

Showy Seed Heads

  • Calamagrostis: Feather Reed Grass
  • Chasmanthium: Sea Oats
  • Descampsia: Tufted Hair Grass
  • Erianthus ( Saccharum): Plume Grass
  • Miscanthus: Miscanthus, Eulalia
  • Moliina: Moor Grass
  • Panicum: Switch Grass
  • Pennisetum: Fountain Grass
  • Stipa: Feather Grass

Drought-Tolerant Grasses

  • Andropogon: Blue Stem Grass
  • Bouteloua: Mosquito Grass
  • Erianthus: Plume Grass
  • Festuca: Fescue
  • Phalaris: Ribbon Grass

Dry, well-drained Soil

  • Elymus racemosus
  • Festuca: Fescue
  • Helictotrichon: Blue Oat Grass
  • Pennisetum orientale: Oriental Fountain Grass
  • Sesleria caerulea: Blue Moor Grass
  • Stipa: Feather Grass

Damp soil

  • Acorus: Sweet Flag
  • Carex: Sedge
  • Chasmanthium: Sea Oats
  • Descampsia: Tufted Hair Grass
  • Glyceria: Manna Grass
  • Luzula: Wood Rush
  • Milium: Golden Grass
  • Miscanthus: Miscanthus
  • Molinia: Moor Grass
  • Panicum: Switch Grass
  • Pennisetum: Fountain Grass
  • Phalaris: Ribbon Grass
  • Spartina: Cord Grass

Hemerocallis hybrids (Liliaceae)

Daylily

Hemerocallis hybrids

Hemerocallis hybrids

Daylilies have been popular since the 1930's. In the spring, grass-like leaves emerge forming a clump. The leaves have a keel down the length in the middle. The leaves range in length from 30 - 60 cm (1 to 2') and are 2.5 cm (1") wide. Open, lily-like flowers bloom from late May - late August, with the peak period in July. The flowers open one at a time from the top of a leafless stem, each lasting one day. Daylilies come in a wide range of colours: yellow, orange, peach, apricot, and rust. They are grown in the border, as a groundcover, mass planted in hard to look after areas, and in large containers. The dense foliage will smother many weeds.

  • Full sun, (some pale colours prefer afternoon shade).
  • Well-drained, ordinary soil. High organic content recommended. Tolerant of drought and neglect.
  • No fertilizing needed
  • Divide anytime, best in early spring or early fall
  • Cut back the flower stems after blooming
  • Cut foliage down in the fall

Ligularia sp. (Asteraceae or Compositae)

Ligularia or Golden Ray

Ligularia sp.

Ligularia sp.

Ligularia is a long-lived, easy-to-care-for plant when grown in cool, moist, fertile soil. Large glossy leaves mound over the soil at the base of the plant. They bloom yellow/orange daisy flowers singly or on spikes, in late summer - early fall. These tall, dramatic plants can be 3 feet across, more in rich soil. Large leafed plants create a bold tropical effect. Plant them as accents, specimens, beside ponds and streams. They always attract attention!

L. dentate:

'Desdemona': Leaves dark purple underneath, bright orange daisy-like flowers.
Grows to 90 - 120(3 - 4').
'Othello': Leaves brownish, blooms slightly earlier than 'Desdemona'.
Grows to 90 - 120 cm (3 - 4').

L. stenocephala:

Leaves deeply toothed, small yellow flowers on narrow, glossy purple-black,
upright flower stems.
Grows to 120 - 180 cm (4 - 6').
Cultivars include 'The Rocket' and 'Sungold'

L. wilsoniana:

Tall spikes of yellow flowers in mid-summer. Grows to 150 - 180 cm (5 - 6')

  • Full sun in wet soil, light shade is better in hot areas where the soil is not wet.
  • Best in a rich, moist soil, but will grow quite well in regular soil
  • No need for fertilizing.
  • Spring division when needed (seldom). Plants take a couple of years to establish

Paeonia hybrids (Paeoniaceae)

Garden Peony

Paeonia hybrids

Paeonia hybrids

Paeonia hybrids

Paeonia hybrids

Peonies have been cultivated in China for centuries. In the late 1700's they were introduced to the rest of the world and have never lost their popularity. They are beautiful, easy to grow and very long lived. Peonies are a focal point in the border when they bloom, and after they remain an attractive shrub-like mounding plant. The Bomb and Double types are the most commonly used Peonies but because the flower heads are very heavy they need staking. Japanese, Anemone and Semi-double types are easier to care for in the garden because the flowers stay up without staking.

Peonies form large, bushy, mounding plants, 75 - 100 cm (30 to 40") x 100cm (3'), with shiny, divided leaves that change colour in the fall to yellow or red. Single flowers form at the top of the stems, (above the mounded leaves) with other buds growing below but usually they do not open. Peonies come in pink, red and white and bloom from late May to mid-June. Ants eat the sticky material on the bud, but this does not help the flowers to open.

Hot humid weather increases the possibility of Botrytis blight. Cut out the affected leaves and stems (they become brown and die back). This is not a common problem and is a sign that the plants are not growing in proper conditions

  • Full sun or light shade.
  • Deep, fertile, well-drained loamy soil
  • An application of sulphate of potash in early spring will help keep the flower stems stronger.
  • Divide the woody crown, (10 - 15 years) in early fall (late August early September in Ottawa). Pieces should have 2 or 3 buds (pips, or eyes) and a good size piece of root to do well. When planting new plants it is important to place the buds at the same depth in the soil as they were at before. Deeper planting will delay flowering. It may take 2 or 3 growing seasons for peonies to develop and flower well again.
  • Deadhead flowers to create a neat dome shaped plant that will be a background to other flowers.
  • Staking is often needed for double cultivars. It should be done before flowering in early spring otherwise the stems may fall and break
  • Cut the stems down to a few cm in late fall and top-dress with 2.5 - 5 cm (1 - 2") of well-rotted compost or manure.

Sedum sp. (Crassulaceae)

Stonecrop

Sedum sp.

Sedum sp.

Sedums are succulent plants adapted to dry conditions. The thick fleshy leaves store water. Low mat forming species often have a wide variety of leaf and flower colour, and are excellent for rock gardens, or groundcovers even on hot, dry slopes. Taller species have beautiful fall colour, attract pollinators and give wonderful colour in borders. All sedums are nice in containers.

S. acre: 8 cm (3"), yellow leaves in spring, turning green, followed by yellow flowers in late summer
S. album:
10 cm (4"), green leaves turn red-maroon in fall, flowers either white or pink
S. anacampseros:
15 - 25 cm (6 - 10"), round blue leaves, purple flowers in late summer
S. cauticola:
10 cm (4"), blue leaves, pink flowers in late summer-late fall
S. cyaneum:
10 cm (4"), blue leaves, rose-pink flowers starting in early fall
S. divergens:
10-15 cm (4-6") globe shaped green leaves, yellow flowers in summer. Native plant.
S. ewersii:
15 cm (6") blue round leaves, rose pink flowers in late summer
S. kamtschaticum:
15 cm (6") Moist soil. Scalloped leaves, yellow or gold flowers in summer
S. oreganum:
15 cm (6") Thick leaves, yellow flower. Native plant
S. reflexum:
15 cm (6") Blue needle-like leaves, yellow flowers.
S. sieboldii:
15 - 20 cm (6 - 8"),blue scalloped leaves, pink flowers in late fall.
S. spathulifolium:
10 cm (4"), rosette of fleshy leaves, yellow flowers in summer.
S. spurium:
15 cm (6") mat forming, often variegated leaves, with pink, red or white flowers.
S. telephium x spectabile
'Herbstfreude': 45-60 cm (18-24") This is the most popular border sedum. Autumn Joy sedum flowers are small but are in large flat-topped heads above the foliage, they start off cream-green and gradually turn from pink, to a deep, bronzy-mahogany red from September - October.

  • Full sun, (partial shade for some cultivars)
  • Well-drained, ordinary soil. Very drought-tolerant
  • No fertilizer needed
  • Divide anytime, best in early spring. Very large plants that need staking should be divided
  • Cutting back stems in spring if you like to see the flower heads poke through the snow

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