Italian arum

Questions about Italian arum

Does Italian arum need sun or shade?

Italian arum grows in part shade (2 to 4 hours of sun, mostly in the morning) and shade (less than 2 hours of direct sun, or bright dappled light). It is one of the few that also put up with deep shade.

It wants soil that stays evenly moist, rich in organic matter, and a good soak in dry spells. It copes with soil that stays wet.

What zones does Italian arum grow in?

USDA zones 5 to 9. It is hardy to zone 5, which means it survives winter nights down to about −10 °F (−23 °C).

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

When does Italian arum flower in my zone?

In zone 5 it flowers early May to late May. 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 Italian arum be planted?

12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 16 in (40 cm), so a group knits into one patch.

It grows 16 in (40 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.

How many Italian arum plants do I need?

At 12 in apart, set out in staggered rows:

• 12 to fill 10 square feet (about 1 m²)
• 11 for a single row 10 ft (3 m) long
• 38 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.

Is Italian arum poisonous to dogs and cats?

Yes: severe toxicity to people, dogs, cats and horses. All parts, especially the berries, contain crystals that cause burning and swelling of the mouth and throat if chewed. The sap can irritate skin.

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

What can I plant instead of Italian arum?

Italian arum is listed as invasive in parts of North America, so the planner never uses it. These do the most similar job, and are native:

• Fawn lily 'White Beauty': the same job in a bed; 6 in shorter, 7 in narrower.
• Jack-in-the-pulpit: the same size and the same flowering time; an accent, not a bulb layer, green, not cream.
• Woodland phlox: the same flowering time; a drift, not a bulb layer, 4 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 Italian arum?

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.

Will Italian arum spread?

It spreads sideways, by runners or roots; the risk of it taking over is high. Spreads by seed carried by birds and by small tubers that break off when it is dug, and is very hard to remove. Listed as invasive in the Pacific Northwest and the mid-Atlantic states, and regulated as a noxious weed in Washington State.

It is listed as invasive in parts of North America, and the planner never chooses it.

What can I plant to hide Italian arum'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:

• Hosta: 18 in tall and 2½ ft wide, a recorded partner, in flower mid July to mid August.
• Lady's mantle: 18 in tall and 24 in wide, in flower late May to early July.
• Bleeding heart: 2½ ft tall and 24 in wide, in flower early May to early June.

What does Italian arum look like in winter?

Italian arum 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.