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Butterfly garden plants — host vs nectar plants explained
Butterfly garden plants split into host plants (where butterflies lay eggs) and nectar plants (adult food) — milkweed, zinnia, lantana and more.
Butterfly garden plants — host vs nectar plants explained
Most "butterfly garden" plant lists are really just nectar plant lists. They feed visiting adult butterflies for a few weeks and then the butterflies leave. A butterfly garden that actually supports a population — including the caterpillars no one wants to talk about — needs both host plants (where eggs are laid and caterpillars eat the leaves) and nectar plants (where adults feed). This guide separates the two categories for US and UK gardens, explains why monarchs need specifically milkweed and not just any flower, and flags the pet-toxicity issues several signature butterfly plants carry.
Try Growli: Photograph a caterpillar in your garden and Growli will ID the species and tell you which host plant it eats — so you can plant more.
The single biggest mistake in butterfly gardening
Butterflies have two life stages with completely different food needs:
- Caterpillars (the larval stage) eat leaves. They are usually fussy — monarch caterpillars eat only milkweed (
Asclepiasspecies); black swallowtail caterpillars eat plants in the carrot family (parsley, dill, fennel, Queen Anne's lace). Without the right host plant, butterflies cannot reproduce in your garden. - Adult butterflies drink nectar from a wide range of flowers. Adults are generalists; caterpillars are specialists.
If you plant only nectar (zinnia, butterfly bush, lantana), you get visiting adults from neighbors' gardens. If you plant only host (milkweed alone), you get caterpillars but few adults stopping by. The combination is the win.
Pet safety boilerplate: Two signature butterfly host plants — milkweed and butterfly bush — are flagged below for pet toxicity. The full toxic-plant list is at the ASPCA Animal Poison Control website; the emergency line is (888) 426-4435.
Host plants (where butterflies lay eggs)
Pick host plants by the butterfly species native to your region. The list below covers the most common North American garden butterflies plus UK-relevant species.
1. Milkweed — Asclepias spp. (monarch host)
The single most important plant for monarch butterflies. Monarchs lay eggs only on milkweed; caterpillars eat only milkweed; the cardenolide toxins in milkweed sap become the caterpillar's lifelong chemical defense (orange-and-black warning coloring tells predators "I taste terrible"). Choose regionally appropriate native species:
- US Northeast / Midwest: common milkweed (
A. syriaca), swamp milkweed (A. incarnata), butterfly weed (A. tuberosa) - US Southwest / California: showy milkweed (
A. speciosa), heartleaf milkweed (A. cordifolia) - US Southeast / Gulf: aquatic milkweed (
A. perennis)
Important: avoid tropical milkweed (A. curassavica) in southern US zones — it does not die back in winter, disrupts monarch migration and can spread the OE parasite. Stick with regionally native species.
Pet safety: ASPCA flags milkweed as TOXIC to dogs, cats and horses — contains cardiac glycoside cardenolides. Symptoms include vomiting, weakness, dilated pupils, seizures. Most pets avoid it because of the bitter taste, but the milky sap is irritating to skin and eyes — wear gloves when cutting.
2. Parsley, dill, fennel — Petroselinum crispum, Anethum graveolens, Foeniculum vulgare (black swallowtail host)
Black swallowtail caterpillars eat plants in the carrot family. Tolerate some chewing on your herb bed — those bright green caterpillars with black bands and yellow dots become some of the most striking butterflies in the US East. Pet safety: parsley and dill are non-toxic per ASPCA; fennel in large amounts can be mildly toxic to dogs and cats — usually mild GI upset.
3. Queen Anne's lace — Daucus carota (black swallowtail host)
The wild carrot ancestor; the same family as #2 above. Considered invasive in parts of the US Midwest — confirm local status before planting. Native cousin: golden alexander (Zizia aurea) is a better US Midwest choice. Pet safety: generally non-toxic.
4. Spicebush — Lindera benzoin (spicebush swallowtail host)
US Northeast woodland understory shrub with aromatic leaves and small yellow spring flowers. The only host for spicebush swallowtail caterpillars. Berries feed migratory birds in fall. Pet safety: not on ASPCA toxic list; generally regarded as non-toxic.
5. Sassafras — Sassafras albidum (spicebush + tiger swallowtail host)
Eastern US native tree with mitten-shaped leaves and stunning fall color. Hosts both spicebush swallowtail and Eastern tiger swallowtail caterpillars. Pet safety: sassafras root contains safrole — avoid letting pets chew bark or roots.
6. Passion vine — Passiflora incarnata (gulf fritillary + zebra longwing host)
Native US Southeast vine with extraordinary purple-white-yellow flowers. The host plant for gulf fritillary and zebra longwing butterflies. Cold-hardy to zone 6. Pet safety: Passiflora caerulea (blue passion flower) is mildly toxic; P. incarnata is generally regarded as low-risk but contains alkaloids — keep pets from chewing foliage.
7. Hops — Humulus lupulus (comma + question mark host)
Vigorous perennial vine used to brew beer; native to UK and naturalized across US. Host for several anglewing butterflies (commas, question marks). Pet safety: TOXIC to dogs per ASPCA — particularly the spent hops left after brewing can cause malignant hyperthermia. Keep dogs away from hop plants and any homebrewing waste.
8. Stinging nettle — Urtica dioica (UK red admiral + small tortoiseshell host)
The single most important butterfly host plant in the UK — red admiral, small tortoiseshell, peacock, and comma butterflies all lay eggs on nettle. Allow a clump in a corner of the garden where you can ignore the sting. Pet safety: mechanical sting hairs irritate skin; not chemically toxic.
9. Birdsfoot trefoil — Lotus corniculatus (common blue host)
UK-native legume; host for common blue butterfly and several skippers. Yellow pea-flowers self-seed in lean soil. Pet safety: large amounts can cause mild bloat in grazing livestock; not on common pet toxic lists for dogs/cats at garden quantities.
Nectar plants (adult butterfly food)
Nectar plants are generalists — many butterfly species will visit. The picks below have heavy butterfly traffic across most of the US and southern UK.
10. Zinnia — Zinnia elegans
Cheap, easy from seed, and one of the heaviest butterfly nectar producers in any annual. Tall single-flower forms (not double) get the most traffic. 'State Fair' and 'Cut and Come Again' are reliable beginner cultivars. Pet safety: non-toxic per ASPCA.
11. Lantana — Lantana camara
Cluster of small bright yellow-orange-pink flowers from spring to frost in warm zones; annual elsewhere. Magnet for swallowtails and skippers. Pet safety: TOXIC to dogs, cats and horses per ASPCA — contains liver-damaging triterpenoids. Symptoms include depression, vomiting, weakness; ingestion of green berries is the most dangerous. Avoid where pets graze.
12. Verbena — Verbena bonariensis
Tall airy purple flower clusters on wiry 4 ft stems. Self-seeds; one of the longest-blooming nectar plants in the garden. Pet safety: generally regarded as non-toxic; not flagged by ASPCA.
13. Coneflower — Echinacea purpurea
Native US prairie daisy; flat landing pad for swallowtails and fritillaries. Also a bee plant — covered in our bee friendly plants guide. Pet safety: generally non-toxic.
14. Pentas — Pentas lanceolata
Tropical bedding plant (annual in most US zones) with star-shaped pink, red, white or lavender flowers. Heavy hummingbird and butterfly traffic. Pet safety: generally non-toxic; not flagged by ASPCA.
15. Salvia — Salvia spp.
Tubular flowers preferred by swallowtails and skippers; covered in detail in our hummingbird plants guide. Pet safety: common salvias are generally non-toxic.
16. Butterfly bush — Buddleja davidii
Long honey-scented panicles in purple, white or pink from July to first frost. Despite the marketing, butterfly bush is a nectar plant only — not a host plant. Adults visit; caterpillars cannot eat it. Caveat: invasive in parts of the US Pacific Northwest and mid-Atlantic — confirm local status; consider native alternatives like buttonbush (Cephalanthus occidentalis) or sweet pepperbush (Clethra alnifolia). Pet safety: not on ASPCA toxic list.
17. Joe pye weed — Eutrochium purpureum
Native US perennial, 4–7 ft, with massive mauve flower heads in August–September. Heavy swallowtail traffic. Pet safety: generally non-toxic.
18. New England aster — Symphyotrichum novae-angliae
Native US aster with deep purple daisy flowers in September–October. Critical late-season fuel for monarchs heading south. Pet safety: non-toxic; not flagged by ASPCA.
19. Goldenrod — Solidago spp.
Spires of yellow flowers from August to October — peak migration fuel for monarchs and many other species. Pet safety: generally non-toxic.
20. Yarrow — Achillea millefolium
Flat-topped white, pink or yellow flower heads from June to September. Pet safety: TOXIC to dogs and cats per ASPCA — causes drooling, vomiting, increased urination.
A note on regional differences (US vs UK)
The US has roughly 750 native butterfly species; the UK has 59 resident species plus a handful of migrants. The split is dramatic:
- Monarch migration is US-specific. UK gardens see vanishingly few monarchs (a handful of stragglers blown across the Atlantic per decade).
- Swallowtail diversity favors the US. The UK has one swallowtail — the rare Norfolk-confined
Papilio machaon britannicus, which feeds on milk parsley (Peucedanum palustre), not the garden parsley that hosts US black swallowtails. - UK signature butterflies are nettle specialists. Red admiral, peacock, small tortoiseshell, comma — all need stinging nettle as host. A patch of nettle in a UK garden corner is the single highest-leverage host plant move.
For US planting, see the Xerces Society regional plant lists. For UK, the RHS "Plants for Pollinators" mark identifies vetted nectar plants.
How to plant for butterflies
1. Pair host and nectar plants in the same bed
Don't put milkweed in one corner and zinnias in another. Adult monarchs lay eggs on milkweed and nectar from milkweed and nearby flowers — a 6 ft mixed drift works far better than scattered single plants.
2. Choose sunny, sheltered spots
Butterflies are cold-blooded — they need 6+ hours of sun to fly, and prefer beds out of strong wind. South or southwest exposures with a fence or hedge windbreak are ideal.
3. Plant in drifts of 3–5 per species
Same rule as bee plants. Butterflies forage by sight; a clump of five zinnias gets exponentially more visits than five scattered ones.
4. Add a damp mud spot
Adult males of many species "puddle" on damp mud to extract salts and minerals. A shallow saucer of compost-rich wet soil refreshed daily provides this.
5. Skip all sprays
Even "organic" Bt (Bacillus thuringiensis) kills caterpillars. The whole point of a butterfly garden is to keep caterpillars alive. If you cannot tolerate any chewed leaves, butterfly gardening will frustrate you — accept some leaf damage as a sign the garden is working. For pest management without harming caterpillars, see our pests hub.
Try Growli: Photograph a butterfly visiting your garden and Growli will identify the species and tell you whether you have the right host plant for it to lay eggs.
Related articles
- Bee friendly plants — 20 picks pollinators actually visit — the bee-specific guide
- Hummingbird plants — 15 nectar-rich picks — for hummingbirds
- Types of flowers — 20+ annuals and perennials — the broader flower category overview
- Companion planting guide — combining pollinator plants with vegetables
- Pet-safe houseplants — indoor alternatives
- Pests hub — no-spray approach — pest management that does not harm caterpillars
Reviewed and updated by the Growli editorial team. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.
Frequently asked questions
What is the difference between host and nectar plants?
Host plants are where butterflies lay eggs and caterpillars feed — they are usually species-specific (milkweed for monarchs, parsley/dill for black swallowtails, passion vine for gulf fritillaries, stinging nettle for UK red admirals). Nectar plants are where adult butterflies feed and are generalist — zinnia, lantana, verbena, coneflower, salvia, butterfly bush all attract many species. A real butterfly garden needs both. Nectar alone attracts adults briefly; host plants keep the next generation.
What is the best plant to attract monarch butterflies?
Native milkweed (*Asclepias* species) is the only host plant monarch caterpillars can eat — pick species native to your region (common milkweed *Asclepias syriaca* in the US Northeast and Midwest, butterfly weed *Asclepias tuberosa* for drier soils, swamp milkweed *Asclepias incarnata* for moist soils). Avoid tropical milkweed (*Asclepias curassavica*) in the US South — it disrupts migration and spreads disease. Pair milkweed with nectar plants like zinnia, joe pye weed and late asters for adults.
Are butterfly garden plants safe for pets?
Most nectar plants are safe — zinnia, verbena, coneflower, pentas, butterfly bush, joe pye weed, aster and goldenrod are non-toxic per ASPCA. Milkweed, lantana, yarrow and hops are flagged toxic. Milkweed is the most important host plant for monarchs but contains cardenolides — symptoms in pets include vomiting, weakness, seizures. Plant milkweed where dogs cannot chew foliage, and never let pets drink from a vase of cut milkweed. See our [pet-safe houseplants guide](/blog/pet-safe-houseplants) for indoor alternatives.
Does butterfly bush actually attract butterflies?
Yes — it is one of the heaviest nectar producers in any flowering shrub. But it is a nectar plant only, not a host plant: adult butterflies visit, but caterpillars cannot eat the leaves. So butterfly bush feeds visiting adults but does not support a reproducing population. Also note buddleia is invasive in parts of the US Pacific Northwest and mid-Atlantic — consider native alternatives like buttonbush or sweet pepperbush in those regions.
Can I have a butterfly garden in a small space?
Yes — even a 4x4 ft bed or three large containers can support butterflies if you pair one host plant with two nectar plants. A container milkweed plus a zinnia clump and a salvia will reliably attract monarchs and skippers. In the UK, a corner patch of nettle plus a pot of verbena bonariensis covers most of the resident garden butterfly species. Density beats square footage — pollinators find concentrated plantings more easily than scattered ones.
What attracts butterflies but not bees?
Honestly, very little — most butterfly plants also attract bees and other pollinators, which is good for the garden. Butterflies prefer flat landing pads (zinnia, lantana, verbena, coneflower) and tubular flowers with moderate-length nectar tubes that match their tongue length. They are more attracted to pink, red, orange and yellow than bees, which prefer purple and blue. But almost any single-flower nectar plant will get both bee and butterfly traffic — see our [bee friendly plants guide](/blog/bee-friendly-plants) for the bee-specific picks.
Why are caterpillars eating my plants — is that a problem?
If they are eating host plants, no — that is exactly the point of a butterfly garden. Monarch caterpillars on milkweed, black swallowtail caterpillars on dill or parsley, swallowtail caterpillars on spicebush — all expected and desired. Plant extra so you have plenty for both you and the caterpillars. If the caterpillars are eating plants you wanted to keep pristine, you can move them by hand to a host plant elsewhere, but the simpler approach is to grow extra parsley and dill specifically for caterpillars.
When should I plant butterfly garden plants?
Spring after last frost for most annuals and tender perennials (zinnia, lantana, verbena, pentas). Native perennials like milkweed, joe pye weed and asters can be planted in spring or fall — fall is often better for establishment because the roots grow while top growth is dormant. Direct-sow zinnias, sunflowers and cosmos as soon as soil reaches 60°F. See our [garden soil preparation guide](/blog/garden-soil-preparation) for bed prep timing.