A knee-high clump of wispy leaves, dotted with flowerheads of violet blue, purple with a white eye, or bright yellow: that is centaury (Centaurea sp.). It fears neither drought nor chalky soil, so it brings bloom to beds, pots, rocky terrain and edges — as long as it gets full sun and drainage.
| Botanical name | Centaurea sp. |
|---|---|
| Common name | Centaury |
| Family | Asteraceae |
| Type | Perennial |
| Bearing | Clump |
| Height | 8 to 40 inches (20 to 120 cm) |
| Planting density | 3 to 8 plants per sq. yard (m²) depending on the species |
| Exposure | Full sun |
| Soil | Any type, as long as well drained |
| Flowering | Late spring to early autumn depending on the species |
Centaury is a type of perennial that includes plants that are very different. It doesn’t fear drought, nor does it particularly hate chalky soil. Centaury is excellent to bring blooms to hard-to-flower soil types.
Centaury loves full sun and doesn’t complain much about the type of soil, as long as it drains well.
The larger the plant variety when mature, the farther apart they must be planted. When these rules are followed, there won’t be any planting trouble at all for Centaurea.
The genus covers plants that are very different, from knee-high perennial clumps to tall annuals for cutting. These are the ones you are most likely to find on a garden-centre bench or in a seed catalogue.
| Variety | Flower colour | Height | Flowering season | Best for |
|---|---|---|---|---|
| ‘Black Ball’ | Deep maroon-black | 28–32 in (70–80 cm) | Early summer to late summer | Cut flowers and dried posies |
| ‘Blue Boy’ | Deep cornflower blue | 30–36 in (75–90 cm) | Early summer to early autumn | Cutting and annual meadow mixes |
| ‘Alba’ | Pure white | 18–24 in (45–60 cm) | Late spring to midsummer | Cooling down a hot-coloured border |
| ‘Amethyst in Snow’ | White petals, deep violet centre | 16–20 in (40–50 cm) | Late spring to midsummer | Front of a sunny border |
| ‘John Coutts’ | Rose-pink with pale centre | 18–24 in (45–60 cm) | Early summer, again in late summer if cut back | Dry, sunny borders |
| ‘Gold Bullion’ | Blue over chartreuse foliage | 12–16 in (30–40 cm) | Late spring to midsummer | Foliage contrast in beds and pots |
This is very simple: the only care it needs is deadheading to trigger new blooming. At the beginning of spring, cut the clump back to remove dead foliage and any portions that might have been damaged by frost.
Two options are most effective to multiply centaury: dividing the clump or collecting and sowing seeds.
To divide your centaury, pull it out with a spade and then chop the root ball in half. After that, plant each of the portions as if it were a new plant.
Centaureais a perennial that self-sows abundantly. If you aim to propagate it, you can simple unearth natural seedlings and transplant them elsewhere.
Slugs and snails are likely to devour young sprouts. Setting up a barrier will help solve the problem. Centaury also tends to be vulnerable to powdery mildew. If ever you notice some on a few leaves of your plant, feel free to cut it back completely and then water regularly until new growth reappears.
Centaury will love growing in flower beds, pots, rocky terrain and edges. The best species to pair it with depends on what role it plays in the landscaping.
Centaurea pairs well with perennials that might have similar blooming and leafage: sage, lavender. The bright yellow of a Sedum acre can also work marvels when it’s right next to any of the types of centaury. Just the same for Pennisetum which, when it blooms, seems to chat with the flowers of Centaurea montana as if they were best friends.
This very original candidate has bright yellow flowers, it’s also one of the tallest types of centaury since it reaches 4 feet tall (1.2 meters).
Its cute purple flowers with a white center, and pubescent gray colors make it one of the most beautiful species of centaury.
Perhaps the most common garden centaury of all, it bears violet blue flowers with thin, wispy petals.
Also exists in a pure-white blooming cultivar called ‘Alba’.
