Host Plant Care Guide

Dill

Annual (all zones)

Direct sow in spring. Grows quickly; plant in succession every 2–3 weeks for a continuous supply. Caterpillars can strip a plant fast, so grow plenty.

Fennel

Zones 4–9

Plant away from tomatoes and peppers (allelopathic). Bronze fennel is especially ornamental. Caterpillars love both leaf and flower heads.

Parsley

Zones 5–9 (biennial)

Slow to germinate; soak seeds overnight before planting. Biennial -leave it in the ground over winter to flower in year two, which also feeds adult butterflies.

Common Milkweed (Asclepias syriaca)

Zones 3–9

Spreads by rhizomes -give it space or contain with a root barrier. Cut back after first bloom to encourage fresh growth monarchs prefer.

Butterfly Weed (Asclepias tuberosa)

Zones 3–9

Does not spread aggressively. Stunning orange blooms. Slow to emerge in spring -mark its location so you don't accidentally dig it up.

Swamp Milkweed (Asclepias incarnata)

Zones 3–6

Great for rain gardens or pond edges. Pink blooms July–August. Cut back tropical milkweed varieties in fall to encourage migration behavior.

Lemon

Zones 9–11 (container elsewhere)

In colder climates, grow in containers and bring indoors in winter. Caterpillars mimic bird droppings -look carefully before pruning.

Key Lime

Zones 10–11 (container elsewhere)

More cold-sensitive than lemons. Grows well in large containers. Thorny branches -wear gloves when pruning.

Purple Passionflower (Passiflora incarnata)

Zones 6–10

Hardy native; dies back to roots in winter in zones 6–7. Vigorous grower -provide a trellis or fence. Stunning flowers also attract bees and hummingbirds.

Maypop (Passiflora incarnata)

Zones 5–9

Same species as purple passionflower, regional name. Spreads by underground runners. Edible fruit is a bonus for wildlife.

Tomato

Annual (all zones)

Hornworm caterpillars are large and hard to spot. Check the undersides of leaves. If you find one, consider moving it to a wild tobacco plant rather than destroying it -it'll become a beautiful moth.

Wild Tobacco (Nicotiana rustica)

Annual (all zones)

A great dedicated host plant to grow alongside your vegetable garden so hornworms have an alternative to your tomatoes.

Common Mallow (Malva sylvestris)

Zones 4–8

Self-seeds readily; great for naturalizing a border. Blooms most of the growing season. Also a food source for adult Painted Ladies.

Hollyhock (Alcea rosea)

Zones 3–8 (biennial)

Biennial -plant two years in a row to always have blooms. Stately background plant at 4–6 feet tall. Painted Lady larvae love the leaves.