Crocus

Questions about crocus

Does crocus need sun or shade?

Crocus grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).

It wants ordinary well-drained soil, of average fertility, and little watering once settled.

What zones does crocus grow in?

USDA zones 3 to 8. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °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 crocus flower in my zone?

In zone 5 it flowers late March to mid April. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.

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 crocus be planted?

4 in (10 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.

It grows 5 in (12 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many crocus 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 eight in two groups.

Is crocus poisonous to dogs and cats?

Yes: mild toxicity to dogs and cats. May cause mild stomach upset if eaten. This is the spring crocus, not the highly poisonous autumn crocus (Colchicum).

Is there a pet-safe plant like crocus?

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

• Striped squill: the same job in a bed, the same size and the same flowering time; blue, not purple.
• Grape hyacinth: the same job in a bed and the same size; flowers mid April to early May, blue, not purple.

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

What can I plant to hide crocus'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 crocus look like in winter?

Crocus 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.