Foodplants for Butterflies and Moths

What would you think about if I asked you for good foodplants for butterflies and moths? Buddleja? Verbena bonariensis? Hebe?
It’s true – they’re all great nectaring plants, and non-native to the UK. So why should I bother with native plants if I want to encourage butterflies and moths?

Well, many native plants are very good sources of nectar, of course. Hemp agrimony, knapweed, honeysuckle, wild marjoram and field scabious spring immediately to mind. These are all attractive and in some cases long flowering wildflowers. As nectar plants are they as good as the ornamentals? It’s a far from straightforward question and not my topic here!

Celastrina argiolus
Holly Blue on Holly leaf
Where native plants incontrovertibly DO win is as foodplants for caterpillars. British caterpillars, by and large, need British plants to munch. This can, of course, extend to cultivars, which explains why cabbages are regularly written off. There are exceptions too; I offer up nasturtiums (from South America) in my veg patch as a sacrifice to happy Small White caterpillars.*

At this point gardeners say they have a nettle patch for caterpillars. Well yes – good foodplant but not enough on their own. Atropos Publishing has a good guide which shows which species of butterfly and larger moth depend on which foodplant. Urtica – nettles – have 35 associated caterpillars. It highlights the difference between imported plants and native. Buddleja are a good example; the book lists only 3. This is very different to a native plant – field scabious has 14.

Grasses too are good larval foodplants, which is one of the reasons why we encourage people to sow meadow mixes rather than just wildflowers. Cocksfoot, for example (although not ideal for a meadow), comes in as supporting 35 different types of caterpillar.

Trees and hedge species are even better. Sometimes they have almost exclusive or totally exclusive relationships with individual plants. I think of Yellow Brimstones and Buckthorn, Purple Emperors and Oak, Brown Hairstreak and Blackthorn. The king of all our plants is the Oak; according to the book, both oaks support over 120 types of moth and butterfly caterpillars. It’s said an oak tree will lose around half its leaves to insects in an average year.

Which are the top five foodplants? They’re all native trees or shrubs:
English and Sessile oaks (Q. robur and petraea)
Willows (Salix spp.)
Birches (Betula spp.)
Hawthorn (Crataegus spp.)
Blackthorn (Prunus spinosa)

*and thence happy blue tits etc.etc.

Native And Exotic Plants In The Garden

Robin Lane-Fox wrote a bad tempered piece in last weekend’s FT about “exotic” v. “native” plants in the garden. He’s a respected plantsman, and so I wasn’t surprised to read he was against using native plants in the garden. I’m entirely sympathetic to this view; we are all masters and mistresses of our own gardens, and should do with them whatever we most enjoy. What did surprise me, however, is that he repeated the mantra that our wildlife was oblivious to the difference between (plain) native plants and attractive exotics. It’s true that disease threatens many of our “native” tree species. Sadly we would do well to think about alternatives for planting schemes. When we do, it would also be advisable to source them from UK nurseries so that a raft of new diseases doesn’t reach our shores. Improved biosecurity and more UK grown plants may be rare Brexit dividends.

Plants for Pollinators
It’s also right that “exotic” plants can be at least as beneficial to some wildlife as “native” plants – in some cases more so. Many bees, butterflies and other pollinators benefit from the longer and different flowering periods. There’s also the heavy nectar production of some attractive exotic flowers. We sell a fantastic seed mix from Flowerscapes which illustrates this. However – and this is a big but – it’s wrong to think of plants purely as providers of pollen and nectar. Even if we did there are bee species which are oligoleges – i.e. they feed from a specific plant genus or even single plant species.

Plant Food
I imagine there are no Brimstone butterflies in the doubtlessly beautiful Lane-Fox garden. Brimstone larvae dine exclusively on the leaves of one of our dullest looking shrubs, Buckthorns*. Many moth and butterfly larvae have similarly exclusive or nearly exclusive relationships with other native plants as do many thousands of insects. This includes the Blackthorn so disliked by Mr Lane-Fox.  Quercus robur – that’s the English oak, not your imported tat – supports up to 400 different species of herbivore insects in the UK. This kind of dependence is true of amphibians and mammals – no boring old hazel, no boring old dormice.

My own garden is less ornamental and more nature reserve, but that’s what gives me pleasure. It’s a smorgasbord of natives and exotics, vegetables and fruit trees. It’s also full of the munching, buzzing, swimming things which can’t survive in the surrounding farmland.

*Our bees also seem very partial to Purging Buckthorn‘s inconspicuous little flowers.

Planting Native Hedges: Why and How To

We forget why and how to plant a native British hedge. We take them for granted. They’ve got a history going back to the bronze age, making them one of the oldest man made features in the British landscape. Native plants make a good, fast growing privacy hedge which is recommended for security. They’re also beautiful things and a fantastic resource for wildlife and foragers. Mixed hedges using native species are easy to recreate and manage, and I’m always surprised that more folk don’t go for them.

Why a Native Hedge?

Our native hedge plants seem to me to be a bizarrely under-utilized resource in urban environments in particular. Perhaps people associate them with unruly mixed hedges, when they want a clean and tidy look. In which case, why not suggest a clipped single species? These plants can be as architectural as yew or box; use Hawthorn, for example. Like Blackthorn, a great security barrier but beautiful in spring, and fruitful in autumn.

For summer colour, completing all year round interest, punctuate with our native Honeysuckle, Lonicera periclymenum, or Dog rose, Rosa canina. To my mind, though, the more species in a hedge the better, if for no other reason than increasing its associated biodiversity. Structurally mixed hedges look sounder to me as well; you need a good mix of suckering species like Blackthorn and Hazel to continue to give it a good thick base.

This means a traditional hedge is excellent for security. If native hedges have kept cows and sheep out for hundreds of years, they’ll deal with people too! Hawthorn and Blackthorn – the clues are in their names – make impenetrable barriers. Hawthorn’s synonym – “Quickthorn” – also tells you how fast it will grow

Native hedge plants make good visual screens too. Beech and Hornbeam keep their leaves in hedges, and additionally to Yew, Holly and Privet are also evergreen.

Wildlife

As with all our native plants, common hedge species have unique relationships with our native fauna. When they think about the food that they provide most people think about the berries for birds and small mammals – and larger mammals like gardeners! There’s a largely unnoticed community of animals further down the food chain, however, which depends on a hedge for other forms of sustenance.

Our butterflies and moths have unique relationships with our native plants, many of which you can include in a hedge. The Yellow Brimstone, for example, lays its eggs on Buckthorn, on which its caterpillars feed exclusively. Brown Hairstreak has a similar relationship with Blackthorn.

Think of the number of plants in a native hedge and you can imagine the volume of pollen and nectar even a short length will produce, as opposed to individual plants. The mix of species also ensures a long flowering period – there’s rarely a time when something isn’t in bloom. Hereabouts it’s the Blackthorn blossom in early spring which saves the honey bees from starving, and at the end of the season the ivy in autumn lets them stock up for winter on warm autumn days. Different flowers attract different pollinators, so a mixed native hedge will support a whole range of them.

Plants like blackthorn and hawthorn provide fantastic shelter for invertebrates, small mammals and birds. Hedges are handy corridors for wildlife too, and offer relative safety for animals while they move about. One of the issues exercising the conservation lobby at the moment is the fragmented nature of biodiversity hotspots, which need to be joined up. Hedges can be a pretty good way to do it, at least on a small scale. Animals don’t just use them as “wildways”, but also as navigation features. Bats use them to find their way across the landscape, for example, and bumblebees fly by them too.

Starting a Hedge

It couldn’t be easier to start a native hedge – after all, these are our British plants, so it should be easy to grow them! Before you start, prepare the ground by weeding or spraying off a strip about a metre wide. If you have livestock, thin about whether it would be best to wire the hedgeline before or after you plant your new whips. Don’t under-estimate the width your hedge will grow to.

Find a good quality supplier of British plants. There are plenty online, but do look carefully – please source your plants from a British nursery. Some of the large scale hedge renovation over the last 20 years has used plants from all over Eastern and Western Europe. There are lots of reasons to use hedge plants with British provenance. Some suppliers are either coy about provenance or infer it, so ask.

You’ll need 5 plants per linear metre to create a stockproof staggered double thickness hedge. We usually recommend 50cm between rows. That’s not to say your hedge must look like that. You might not have enough room for two rows of plants, for example, although the thicker the hedge the better from the point of view of wildlife. Some folk want a really thick, triple thickness hedge (7 plants a metre). If you wanted something optimal for a “wildway” you could plant rows up to 1m apart.

Most woodland nurseries sell a “conservation hedge mix”, which is a good diverse default mix for the agnostic and will qualify for grants. It’s suitable for a wide range of situations and soils and consists of species widespread across the UK. If there are species in it you don’t want or species you particularly do, the nursery will usually happily tweak it for you. We don’t suggest using Blackthorn in a hedge next to a lawn, for example, because it suckers freely. On the other hand, you do want some suckering species, like dogwood and hazel, to help thicken up the hedge. Alternatively you might want a more formal single species look – a hawthorn hedge looks good, for example.

Most farmers buy the smallest size plant on offer, which is often 40-60cm. Personally I’d stretch to the next one up, say 60-90cm, which is the size we used in the picture. They’re still pretty small whips, which are easily planted and quick to establish. There is no point buying anything bigger as you’ll end up with a hedge with no bottom.

The whips will be bare root as they’re much easier to transport and will take much better than pot grown. They’re consequently delivered from November while they are dormant. They should arrive in special packaging, so will sit in the shed/garage quite happily for several days. If you’re not planting them for a longer period, heel them in somewhere.

When you do get around to planting your whips the key thing is to keep the wind drying their roots out. I march around with the whips in a bucket of water. The other big issue is frost; don’t try sticking them into frozen ground. They’re easy to plant, particularly if you have a two person planting team. One of you needs to open a slit in the ground with a spade and the other just pops a whip in and treads around it. If you have rabbits or deer you will also need the ubiquitous plastic spiral and cane. These will also help support and generally protect the young hedge plants. The wretched things aren’t biodegradable, however, so if you can fence in your hedge instead that’s a better option.

Management

Laid Hedge

First off, you MUST keep the base of your native hedge clear of weeds. The whips don’t need to compete with perennial weeds while they are getting established. If you don’t use a mulch then you’ll have to weed or spray for a couple of years.

Once established – after a couple of years – removed hedge guards and canes if you have used them.

Without plant management, in a few years’ time you’ll have a different problem to deal with. Although we’ve pretty much arrested the decline in the length of hedges in the UK, they’re beginning to turn into rows of small trees. Left unattended your native hedge will go vertical, which is less helpful for all than a dense hedge with a wide base. You can start this process by pruning the growing tip off your new whips and encouraging lateral growth.

As time goes on the ideal way to ensure a perfect hedge is to lay it, but that’s often not practical. That’s a whole different blog anyway! Establish a trimming regime that impacts the least on local wildlife. The Single Payment scheme asks for hedge cutting to stop between 1st March and 31st July, but the optimum time to do it is January and February. That’s after the berries have been eaten but before birds start nesting.

Same Hedge, 6 Years Later

Don’t butcher a hedge to an inch of its life, as you often see flails do, and trim it in a two or three year rotation to let it fill out. The Single Payment scheme quite sensibly specifies a 2m wide uncultivated zone from the middle of the hedge.

If you do need to take extreme action to get a mature hedge back under control, coppice it in sections, year by year, to minimize the impact on wildlife. Ideally, gap up a hedge while renovating it with locally sourced whips in keeping with the species you see around you.