1. LOCATION AND SIZE
Butterflies prefer gardens that are in full sun. The bigger the garden, the more variety of plants can be grown. However, small gardens or ‘patches’ are important too.
2. ABOUT THE PLANTS
Butterflies (and other pollinators) will come readily to flowering plants and shrubs. However, some plants are preferred because of their nectar value and ease with which the nectar can be extracted. Native plants provide a better source of nectar than introduced plants. Also, some native plants are the preferred food for the caterpillar stage after the eggs are laid on the plants. These plants are known as larval hosts.
This does not mean that introduced plants do not have value. However, due to hybridisation and general alteration of plants grown for the garden centre trade, some introduced species are of no value. For example, flowers that have been bred to develop ‘double’ flowers (ones that look like pompoms, so some dahlias, zinnias and marigolds for example) as the butterflies find it difficult, if not impossible, to extract nectar from these. (See full plant list here)
Plants that have large flat topped flowers (umbels) like milkweeds, fleabanes, tickseeds, and herbs like dill, all provide good landing places for butterflies as well as being good nectar sources. Flat faced single flowers like old-fashioned marigolds, zinnias and daisies are what to look for in non-native species.
Growing a diversity of flowering plants will increase the attraction of your garden to butterflies. It is important to have plants that flower during late spring, summer and fall. Some butterflies will only be obviously in one of the seasons (called ‘flying time), few will fly over all three seasons. It is also preferable to group several plants of the same type together rather than one plant here, another there.
Choosing your plants carefully to ensure a good and appropriate mix of natives and non-natives not only makes for a more attractive garden, but will be the most attractive to butterflies. It is also important to note that many plants that gardeners consider weeds are, in fact, of major benefit to butterflies. For example, Asters and Goldenrods are amongst the best nectar and larval plants so please consider leaving these on your boundaries should they self-seed there, or even within your butterfly garden!
3. OTHER CONSIDERATIONS
Butterflies engage in an activity known as ‘puddling’. They require a damp spot in the garden where they can drink and extract vital minerals derived from the soil. Most bird baths are too deep for butterflies to drink safely, in fact they are in danger of drowning. This means you should ensure a visible damp spot in the garden.
Another requirement is some flat stones located in a sunny spot. Butterflies need the warmth to keep active so they will land on these stones to absorb heat. Leaf litter or piles of brush provide overwintering refuge for the eggs, chrysalis or larvae of some butterflies and other pollinators. If you must rake up your leaves in the fall, leave a pile behind in a corner of your yard.
Butterflies and their larvae (caterpillars) are susceptible to insecticides, even those called ‘natural’. It is important, therefore, to restrict (or eliminate) their use in and around a butterfly garden.