Native cacti in the garden.
Three species of cactus are native to the Canadian Prairies. They are found on uncultivated clay loam, or rocky or sandy soils, and are very common on dry, windswept hillsides. All are low-growing perennials with succulent fleshy stems that are covered with spines. Flowers are large, petals many, in two or more series. Stamens are numerous. Cactus is often found growing amongst prairie grasses such as Spear Grass (Stipa comata Trim & Rupr.) and Blue Grama (Bouteloua gracilis (HBK.) lag.).
Cacti can fit into a landscaped garden in an elevated rock garden or on a well-drained slope.
Mamillaria vivipara (Nutt) Haw./ Pin-Cushion or Ball Cactus
A cushion-like cactus seldom over 5 cm (2") high. Several of these globose plants often grow together forming a mat. The brilliant purple coloured daisy-like flowers appear about the middle of June and continue blooming until the first part of July. The fruit are pale green berries, becoming brown when ripe. The berries are sweet with a very bland flavour. The early settlers often used these berries for making jam.
Opuntia polyacantha Haw./ Prickly Pear Cactus
Their pear-shaped jointed stems are covered with sharp spines. Stems are prostrate growing, often forming dense clumps. Flowers have large waxy petals; brilliant lemon yellow to pinkish orange in colour. Flowers appear about a week later than the Ball Cactus. The fruit is a soft, sweet, flavourful, edible berry.
Opuntia fragilis (Nutt) Haw./ Brittle Prickly Pear Cactus
A low-growing decumbent cactus found in large mats. The "pear" segments are white and woolly and are smaller and rounder than O. polyacantha. The segments stick to ones clothing and to animal fur. They are moved to new places and root easily. Flowers open in late June and early July. The petals are pale yellow and are about 5 cm (2") broad. The fruit is an edible, soft and sweet flavourful berry, round to ovate, 2.5 cm (1") long.
Cacti do extremely well in a desert or semi-arid grassland environment. They need full sun and well-drained soil. They are the hardiest of plants and they can withstand strong winds and drought. They are winter hardy without protection of a snow cover and they tolerate sun and intense radiant heat during the summer months.
The easiest way to propagate them is by division or detaching the pads and putting them in sandy, clay-loam or rocky soil. Plant segments root quickly and plants become established. Cactus can also be propagated by seed. Harvest the fruit in the fall. Plant seeds right after harvesting. Seeds germinate intermittently after several weeks to six months or even a year. Seedlings are fragile so it is best to space the seed so one doesn't have to transplant the small plants. Seeds are available from several internet Web sites or watch for them at your local seed exchange.
Gwen Jamieson works at Agriculture Canada's Cereal Research Centre in Winnipeg, Manitoba. Her interests include wildflowers and perennial gardening. Colour photos, page 102.