Echinacea is of interest as either a beautiful flower, or as an extract that boosts the immune system. This Entry focuses on the flower aspect.
In the winter of 1804, while exploring the western US, Meriwether Lewis found that the Narrow-leaf coneflower made 'an excellent poultice for swellings or soar [sic] throat'. This was Echinacea angustifolia, one of nine species of Echinacea. All nine species contain the medicinal extract. This Entry hopes to help you grow the plant for its blossoms.
Home gardeners tend to prefer E. purpurea, as it is easier to transplant. (The other Echinacea have deep tap roots, but E. purpurea does not.) If, as many gardeners do, you buy potted Echinacea at a garden centre, you will appreciate this difference. The blossoms can be light purple to pink, or white. The flowers have spiny centres, usually at least an inch wide, with petals radiating out from the edges. They are held aloft on thick stems that can be between 18 and 36 inches tall. They start blooming in early July, and can be induced to repeat blooming if you deadhead (remove spent blossoms). The aroma of the spiny centre is sweet, and attracts many types of bees and butterflies, and even hummingbirds.
Another advantage of E. purpurea for a gardener is that it can readily be grown from seed. It's more readily grown from seed than the other Echinacea species. An alternative to planting them in the ground is growing them in planters or pots, which need to be large enough to accommodate their roots. A five-gallon planter (20 litres) is the smallest size that can be recommended for the beginner. If the soil is good and the light is adequate, the only remaining factor will be keeping the plants from drying out. In a rainy summer, this will not be a problem, but dry ones come along sometimes. It will not hurt if you add a little water every day, assuming that excess water can drain through holes in the bottom of the pots. Sometime in April, or even March, you can set out pots or planters in a sunny spot on your windowsill, put potting soil in them, press Echinacea seeds into the soil (a quarter of an inch (half a centimetre) of soil can go over the seeds), and water a bit every day. The seeds will start growing shoots after eight or nine days, and should get enough water so they don't dry out. In late May they can safely be put outside. By mid-June you can dig holes in the ground and carefully remove the contents of the pots and plant them. For more tips on growing, check out h2g2's handy gardening tips. To position Echinacea plants in your garden, read h2g2's principles of landscape design.
E. purpurea does not produce blossoms in its first year, as it lacks the root structure to support them. Once the plants are well-established, though, the roots will likely spread out and sprout additional stems, which will bear more and more blossoms.
So far, we have been talking about the 'species', or original form of Echinacea. A robust industry has developed around special forms of the plant. Some, like the PowWow cultivars, are close enough to the original to be grown from seed. They can even bloom in their first year, if your growing season is long enough. They can also self-seed, though their progeny may not breed true.
Others, like the Sombrero series, are hybrids. They will not self-seed, except in very rare circumstances. The methods by which the colours are developed for these hybrids can be complex, and there isn't the space to discuss this. Nonetheless, the gardener may like the colour of one of these hybrids, and want to buy it as a potted plant.
Just about every year, new cultivars of Echinacea are introduced, so this Entry cannot claim to be comprehensive. If you like this type of plant, plan to visit your favourite garden centre around late June, to see what is available.
Whether to remove spent blossoms or not is up to the gardener. An argument can be made that the seeds and other seed head parts will provide food or nesting materials for birds. It may be an aesthetic judgment, as some people like the appearance of seed heads. In any event, whatever the birds don't eat may sprout the following spring, assuming that the cultivars have produced viable seeds. After winter is over, new growth will likely come up from the roots in April or May. If you have picked a favourable spot for your Echinacea, you may be rewarded with years of blooms.