Blue allium

Questions about blue allium

Does blue allium need sun or shade?

Blue allium grows in full sun (6 or more hours of direct sun a day).

It wants dry, sharply drained soil, of average fertility, and little watering once settled. Once settled in, it stands drought.

What zones does blue allium grow in?

USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).

Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.

Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.

When does blue allium flower in my zone?

In zone 5 it flowers early June to late June. As a summer flower it moves about half a week for every zone: earlier where it is warmer.

Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.

How far apart should blue allium be planted?

4 in (10 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 6 in (15 cm), so a group knits into one patch.

It grows 20 in (50 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many blue allium plants do I need?

At 4 in apart, set out in staggered rows:

• 107 to fill 10 square feet (about 1 m²)
• 31 for a single row 10 ft (3 m) long
• 343 to fill a 4 × 8 ft bed on its own

In a mixed border, plant it as handfuls of five or seven, in the gaps between other plants.

In the bed above, the planner used seven in one group.

Is blue allium poisonous to dogs and cats?

Yes: moderate toxicity to people, dogs, cats and horses. Like all onions, it can damage red blood cells in dogs, cats and horses if eaten. Eating the bulbs in quantity can also upset a person's stomach.

Rated from NC State Extension. Where references disagree, the more cautious rating is used.

Is there a pet-safe plant like blue allium?

These come closest to doing what blue allium does, and no toxicity is recorded for them:

• Triteleia 'Queen Fabiola': the same job in a bed, the same size, the same flowering time and the same colour.
• Grape hyacinth: the same job in a bed and the same colour; belongs at the front, not in the middle, 14 in shorter.

Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.

Do deer eat blue allium?

They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.

What can I plant to hide blue allium's leaves after it flowers?

A bulb's leaves have to be left to yellow for about six weeks after flowering, to feed next year's flowers. Plant it among perennials that come up late and spread wide, and they grow over the leaves as they fade:

• Lady's mantle: 18 in tall and 24 in wide, in flower late May to early July.
• Catmint 'Walker's Low': 24 in tall and 2½ ft wide, in flower mid May to mid September.
• Garden chrysanthemum: 24 in tall and 24 in wide, in flower mid September to late October.

What does blue allium look like in winter?

Blue allium is underground: it dies back after flowering and waits as a bulb until spring. Mark where it is, so a fork does not find it first.

Is blue allium good for bees and butterflies?

Blue allium is visited by bees and butterflies.