You can do things in the garden to help butterflies and bees almost all year round, but a crucial period is in early spring.
In March the first queen bees and adult butterflies emerge from hibernation, stimulated by rising temperatures. But it’s a precarious time as a warm day can wake them up, but this could easily be followed by snow and ice. There are relatively few native plants in flower so early, but three of the most important are Dandelions, Primroses and Willows. Dandelions are treated as weeds by many gardeners, but they are vital sources of nectar to fuel queen bees and butterflies. Willows trees and shrubs can provide nectar too, but are also a really important source of pollen. Queen bees need to collect this pollen, which they store in their nests to feed their future offspring. Nectar is like a sugary drink, giving insects the energy they need to fly.
Gardeners can also help by planting more garden-variety plants, which may not necessarily be native to most of the UK but which are nonetheless useful for insects. Plants like Muscari, Early-flowering Heathers and Lungwort are available in all garden centres and are perennials, meaning they will come back year after year.
By around May the queen bees will have established their nests. Most bumblebees nest underground in cavities, often using old mouse nests. They may also nest under sheds or loose paving slabs, under decking or in compost bins. Some species such as the Tree bumblebee always nest above ground though, and can take over bird boxes. At this stage the queen remains inside the nest, but will have a small number of worker bees which collect pollen and nectar to help grow the nest.
Things will be happening in the butterfly world too: the first white butterflies will appear. Most of those will have spent the winter as a pupa with a hard shell which the caterpillar will have attached to a hard surface like a fence or the stems of shrubs. This final stage of their life cycle sees them emerge as adult butterflies, ready to mate and lay their eggs. The caterpillars of the most common white butterflies lay their eggs on plants in the brassica family. This includes many of the cultivated types like cabbage, broccoli and kale. I grow those plants under netting to prevent the butterflies from laying their eggs on them, but I also grow extras and just plant them in the flower border, where the butterflies are welcome to have them.
I also grow several typical garden plants which happen to be in that brassica family; Honesty and Dame’s Violet are very easy to grow from seed, and last year I noticed that Orange-tip butterflies had laid their eggs on Dame’s Violet in my garden. You can tell Orange-tips from other eggs, as they are laid on the flower stalk close to the flower, and are orange or yellow. Other white butterflies mostly lay their eggs on the leaves. If you’ve got a damp grassy area in the garden, you can plant it up with Cuckoo-flower, which is one of the favourite plants of Orange-tip and Green-veined White butterflies.
As we head toward mid-summer there are countless plants which will be in flower, and in great profusion. Whatever type of garden I’m working with, I always try to include alliums. Alliums are loved by bees especially, and you can see them covered in buzzing bumblebees at this time. There are so many types of allium; you can plant those with tall flower stalks in the borders, but if you’ve only got planters or window boxes you can use smaller varieties. Chives are a type of allium, are very easy to grow, and are useful in the kitchen. Another useful culinary plant is Nasturtium. Nasturtiums have beautiful large flowers with long spurs filled with nectar. You’ll see bumblebees with longer tongues, such as the Garden Bumblebee, reach inside and get a drink to help them on their way. Nasturtiums are also caterpillar food for those white butterflies too, especially the Large White and Small White whose caterpillars chomp away on the leaves. Any leaves which aren’t eaten can be used in salads, and the flowers are edible too! Just check them for eggs or caterpillars first, before you tuck in though.
I love growing herbs, and it happens that many of them are also useful for insects. One of the first to flower is Rosemary, which is soon followed by chives, marjoram and thyme. My favourite varieties of thyme are those called ‘lemon thyme’, with leaves that are heavily-scented liked lemons, and flowers which butterflies and bees enjoy. All of those plants are fairly drought-tolerant and are suitable for planters and pots in sunny places, but you will have to remember to water them at least once a week, even if it rains.
Mint is another useful herb, and there is an incredible array of varieties with differently-scented leaves. There are mints that smell of lavender, orange, apple and even chocolate! Almost all require soil which doesn’t dry out, so they’re best grown in large planters with no drainage holes, or in flower beds or around ponds. They can be quite vigorous and spread out a lot, so if you grow them in a pot sunken into the soil it can help contain them. All produce spikes of small flowers which are visited by bees and butterflies. Catmint is another excellent plant for insects with longer tongues, but isn’t actually a mint so we can’t eat it.
Mints begin to flower in the latter half of summer, and by then many bumblebee colonies will be reaching their largest size, with up to 400 bees in some nests. Around this time, the queen will begin to produce new queens or male bees but she can only do this if the nest is large enough and has enough food. So providing ample nectar and pollen at this stage is vital for the success of the nest. A little-known fact about bumblebees is that they have smelly feet – when a bee visits a flower it leaves a scent from their feet which other bees can detect, so they know there’s little or no food left inside. This helps them avoid wasting time with empty flowers, and really shows how important it is to have a lot of plants blooming at this time so there’s enough to go around.
Garden butterflies too will be peaking, with some of the large, colourful species like Peacock, Red Admiral and Small Tortoiseshell visiting gardens. These species mostly lay their eggs on Nettles or Thistles. If you are happy to have those plants in your garden then that will help those butterflies to reproduce, but even if you don’t have Nettles or Thistles you can at least help the adults by growing nectar-rich plants.
In August through to September there are still plenty of plants flowering. Sea Holly is a favourite of mine, and will grow in dry places or in flower beds. Phlox is a typical cottage-garden plant which can flower from July through to September, keeping the garden colourful well into late-summer. Regular Phlox plants are often used by butterflies and moths especially, as they have long thin tongues which can reach inside the deep flowers. There’s also an annual plant called Night-scented Phlox, which is easy to grow from seed and is very attractive to moths in the evening, when its scent can fill the area around it. Plant if close to your house to get the full benefit of the scent.
By October most bumblebee nests will be finished or close to finishing. Nests only survive a single season, and by autumn the old queen, all the workers and all the males will have died naturally. The only ones to survive at the new queens, which will have mated with males from different nests. They will bury themselves in loose soil and spend the winter underground. They can survive temperatures down to minus 19 degrees Celsius by producing a kind of natural antifreeze in their bodies!
The fates of butterflies vary a lot between the species. Some spend the winter as adult butterflies, hiding in the hollows of trees, in sheds, or even coming into homes. They will slow down while it’s cold, and resume activity in spring or on warm winter days. We also have some species such as the Painted Lady which leave the UK in winter. Each year, Painted Ladies migrate from Africa through Europe and up to the Arctic Circle and back. This usually happens over six generations, with no one butterfly doing the entire journey. In late summer they should be flying south again, so having lots of late-summer nectar-rich plants such as Sedum and Fuchsia will help fuel their journeys. Sedums are succulent plants and can survive a lot of drought so they are excellent options for planters and window boxes. Fuchsias can be grown as large shrubs which can be planted as hedging and in borders, or as small shrubs with trailing stems that look good in hanging baskets.
From November onwards there’s not a lot to do in the garden, and you can help butterflies and moths by generally doing as little as possible. Many of them will be living as caterpillars or pupae attached to plants, so leaving the dead vegetation there through the winter will help them. You can plant bulbs though, and Muscari, Allium and Hyacinth are all good options. Then all you have to do is wait until Spring when your garden will be busy with insects again.