How To Choose Perennials

Six basic perennials for colour from spring to fall

While perennial plants will reappear in your garden year after year, unlike annual plants which flower all summer, perennials only bloom for a limited period of time. However, by choosing your perennials carefully, you can enjoy a stunning flower display from spring until fall. Here are six essential perennials to get you started. With the wide choice of cultivars available in each of these six basic plants, any colour scheme is possible.

Tall Bearded Iris (flowers May to June)
Bearded iris are dry-land plants that need a sunny location and well-drained soil. In planting, the rhizomes (growing point) should be set just below the surface of the soil. To get a bigger clump faster, plant them closer together. After flowering, the flower stems should be cut back but the leaves must be left to manufacture food for the plant until fall. Before winter the foliage should be cut back to within a few inches of the ground and all dead leaves removed. Since iris are very hardy, no winter mulch is necessary; it is best to keep them free of all material which might tend to hold moisture and induce rotting.

Peonies (flowers May to June)
Peonies are long-lived plants that will continue to flower for generations. They need never be disturbed, although if moving them becomes necessary, the large clump should be reduced to sections with three to five eyes. A large clump moved whole would most likely cease flowering. Plant peonies no more than two inches deep, with eyes into the soil.

Daylilies (flowering in July and August)
Daylilies are the heart of the mid-summer perennial garden, flowering non-stop through the heat of July and August. They have a fabulous colour range — apricot, bronze, crimson, gold, lemon, mahogany, maroon, orange, pink, purple, red, violet and yellow. Each lily-like flower lasts only a day but they are continuously in bloom over many weeks. Daylilies are large, wide plants that need at least three feet of space. Plant eyes exactly 1 1/2” deep, top of crown, 3” deep.

Oriental poppies (flowering in June and July)
Oriental poppies colour the garden in June and in September they grow a new basal rosette of leaves. Poppies do best in well- drained soil in full sun or partial shade. To plant poppies, set the root straight down into a planting hole, deep enough that the crown is covered by at least three inches of soil. After June’s giant blooms have faded, the flower heads should be removed and not allowed to form seed. The foliage then dies down and can leave a void in the border. Mulch around the plant for winter protection but do not cover the rosette.

Delphiniums (flowering in June and July, re-flowering in September)
These plants are essential to any perennial border. They need rich, well-drained soil; incorporate well-composted manure in the planting mix and add a mulch or top dressing of compost annually. Delphiniums are best planted in groups of threes. Leave three of the best shoots at approximately 15 cm in height, these delphiniums will produce better flowers on the remaining spikes. Grown like this, the plants are strong enough not to require staking unless they are in a windy spot. After the main flowering period has passed about mid-July, cut some stems to the first leaves and others right to the ground. The plant will then re-bloom in August and September.

Tall phlox (summer phlox) (flowering in August and September)
Tall phlox are invaluable for continuing the summer-long display of colour in the perennial border. Use a lavish hand with these brilliant flowers, choose a few kinds and plant them in irregular drifts for best results. There are a variety of colours from which to choose, many with a contrasting eye. Choose from all the pink ranges (peach pink to salmon and rose), pure white to whites with a colored eye, orange red to scarlet, and mauve to mulberry purple.

This information is provided by Landscape Ontario Horticultural Trades Association, one of the most vibrant associations of its kind in North America, comprised of over 2,000 members, nine sector groups and nine local chapters. Visit to find a professional member near you.