Tall larkspur

Questions about tall larkspur

Does tall larkspur need sun or shade?

Tall larkspur grows in full sun (6 or more hours of direct sun a day), part sun (4 to 6 hours of sun, including some afternoon sun) and part shade (2 to 4 hours of sun, mostly in the morning).

It wants ordinary well-drained soil, rich in organic matter, and a good soak in dry spells.

What zones does tall larkspur grow in?

USDA zones 5 to 8. It is hardy to zone 5, which means it survives winter nights down to about −10 °F (−23 °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 tall larkspur flower in my zone?

In zone 5 it flowers mid July to late August. 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 tall larkspur be planted?

18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.

It grows 5 ft (150 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many tall larkspur plants do I need?

At 18 in apart, set out in staggered rows:

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

In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.

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

Is tall larkspur poisonous to dogs and cats?

Yes: severe toxicity to people, dogs, cats and horses. All parts, especially the young growth and seeds, are highly poisonous if eaten.

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

Is there a pet-safe plant like tall larkspur?

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

• Culver's root 'Fascination': the same job in a bed and the same flowering time; 6 in wider, lavender, not blue.
• Feather reed grass 'Overdam': the same job in a bed; 12 in shorter, flowers late June to mid September.

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

Do deer eat tall larkspur?

Mostly not. NC State lists it as resistant to deer and rabbits. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.

What flowers after tall larkspur?

Tall larkspur is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:

• Japanese anemone: from mid August to early October, 3 ft tall, to stand in front of it and cover its fading stems.
• Garden chrysanthemum: from mid September to late October, 24 in tall, to stand in front of it and cover its fading stems.
• Sedum 'Autumn Joy': from mid August to mid October, 24 in tall, to stand in front of it and cover its fading stems.

What does tall larkspur look like in winter?

Tall larkspur dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.

Is tall larkspur good for bees and butterflies?

Tall larkspur is visited by bees, butterflies and hummingbirds.

It is native to the United States.