The question "what should I grow to attract butterflies to my garden?" You don't have a simple answer, for a variety of reasons. Many butterflies are specialists in fairly strict habitats, limited to, say, grasslands or chalk. Many of these butterflies are rare, but even the relatively common ones are unlikely to visit your garden unless you live next door to their preferred habitat.
When it comes to caterpillar food plants, here are a few you might consider growing:
- Holly and ivy: Holly blue eats both and is relatively common.
- Brassicas: As every gardener knows, large and small whites eat cabbage and other cultivated brassicas, whether they want it or not. Both also eat nasturtium (Tropaeolum majus)
- Crucifers: A wide variety of wild and cultivated crucifers (especially garlic mustard, honesty, and lady's robe) are eaten with the orange tip and the white streaked with green.
- Herbs: Various garden butterflies (small and large, skipper, brown meadow, gatekeeper, and spotted wood) eat wild grasses. If you leave the grass long, there is a chance they will reproduce in your garden.
- Sorrel - Small coppers are not common in gardens, but if they do visit, the introduction of a little sorrel (Rumex acetosa) into a patch of long grass can persuade them to reproduce.
And here are a few you probably shouldn't:
- Nettles: The larvae of many of the more colorful garden butterflies (red admiral, small tortoise shell, coma, and peacock) eat nettles, but all the evidence shows that deliberately growing nettles for them is a waste of time.
- Thistles: food plant of the painted lady, but who wants to grow thistles? Alder and buckthorn bleed
- Sulfur is a butterfly that often visits gardens, but it is a great investment to grow any of these large shrubs in hopes of persuading them to breed.
When it comes to nectar, most butterflies are generally opportunistic; they will take nectar from wherever it is available. One of the best sources is buddleia, and in fact, buddleia is so popular with butterflies that it's tempting to think you don't need to grow anything else. But it's interesting to consider why Buddleia is so good. It has three things going for it:
- Produces a lot of nectar
- Its deep flowers are accessible only to insects with long tongues.
- Its flowers are grouped together so that once a butterfly lands it can easily find plenty of nectar.
But some other plants do all of these things too, for example Verbena bonariensis. And some have mass blooms and a lot of nectar, but flowers that aren't that deep, which for some butterflies is a positive bonus. All butterflies have relatively long tongues, but some are longer than others, and Buddleia flowers are too deep for keeper and stained wood. The ice plant (Sedum spectabile) is good for these two, as are most members of the daisy family (Asteraceae). In fact, about a third of all the plants that have been recorded as butterfly nectar are daisies.
One plant that qualifies as a butterfly favorite because of its large volume of nectar is the bramble. You may not be willing to tolerate the bush in your garden, but with its nectar, berries, and dense, thorny cover for nesting birds, it really is the closest you can get to a 'one-stop shop' for wildlife. .
Daisies, and many of the other plants mentioned, provide plenty of nectar in mid to late summer, but not much early in the year. Some of the best butterfly plants to cover this period are forget-me-nots, snowdrop, primrose, aubrieta, wallflower, blackthorn, willow, and violets.
Annuals rarely produce the volume of nectar that butterflies need, so with few exceptions, the best nectar plants tend to be perennials, biennials, or herbaceous shrubs. While the color of flowers is a poor guide to what butterflies like, a high proportion of butterfly favorites are blue, purple, white, or yellow (avoid bright red).
Butterflies, much more than bees, like to be warm, so they grow on nectar plants that are in a sunny, sheltered location. And to make it easier for the butterflies to refuel without having to fly very far, they grow nectar in large blocks.