Operation HELP A HOSTA
Our essential tips to stop the perennials being devoured by slugs
IHAVE just returned from my garden where a group of hostas are waking up from hibernation. A cluster of hard, pointed leaf buds mark the position of each plant as they nose their way above the surface, poised to start their rapid ascent in spring. Within six to eight weeks the plants will have filled their allotted space as the mass of tightly rolled shoots unfold into leaves.
In their fledging state, my hostas will slip under the radar of slugs and their leaf-munching compadres, snails. However, once shoots extend, they’ll release an aroma that’s irresistible to those slimy molluscs, which have an amazing sense of smell. It’s typical for them to take a chunk out of the tender shoots, ruining nascent leaves before they’ve opened.
Of course, this is just the beginning of a reign of terror. Over the next few months, slugs and snails will lay siege to my hostas, especially on warm, humid nights and damp, cloudy days. Unfortunately, they can turn an intact leaf into a lace doily thanks to a rasping tongue (known as a radula) that’s armed with thousands of microscopic, teeth-like projections.
Ordinarily I have little time for plants that are martyrs to pests and diseases, but I make an exception for hostas. In my opinion, they are the showiest perennials available to add elan to a shady spot with moist soil. Not only do their leaves come in many shapes, colours and sizes, but their long-lasting flower spikes will turn heads and attract bees in summer.
FORTUNATELY, there are lots of ways to prevent hostas from being decimated by ravenous gastropods (the technical term used by botanists to describe invertebrates that move on a flat base).
Whether you raise plants in the ground or in containers, those looking to introduce hostas to their gardens can choose varieties that are more resistant to attack.
It’s safe to say that my quintet of Hosta ‘Patriot’ are certainly not immune to slugs and snails. In fact, if I ignored my plants there would be nothing left of them but a few stumpy stalks by the middle of June. As a result, I have to work hard to keep my hostas hole-free, using a combination of pre-emptive strikes, protective measures and guile.
I start my campaign in late winter, hunting down snails as they hibernate – look under pots, in the shed, holes in walls and other damp, dark places. You might stumble across the odd black slug or another large species, but don’t expect to find too many as around 95 per cent of slugs live in the soil. Before the shoots of my hostas start to grow in earnest, I place organic slug pellets around the crown. The pests are drawn towards the scent of the pellets, eat them and then crawl underground to die. I continue to use pellets until the end of summer, replacing them whenever they’ve all been taken or have broken down after rain.
In the past, the only slug pellets available contained metaldehyde, a pesticide that posed a risk to pets and beneficial wildlife. These were banned from sale in 2021. Pellets certified for organic gardening contain ferric phosphate, a naturally occurring substance that gives plants a boost as they decompose by releasing iron and phosphate into the soil.
Over the years I’ve met gardeners who protect hostas with physical barriers. Some recycle coffee grounds, crushed eggshells and ash, spreading it in a ring around plants. Others prefer to use an off-the-shelf product, such as slug defence gel and wool pellets. I’ve never had great success with any of these, but supporters claim they impede the movement of slugs and snails. If you would prefer to attack slugs head on, try a biological control containing microscopic, slugkilling worms known as nematodes. Available online or from garden centres, nematode-impregnated powder needs mixing with water before being sprinkled on the soil.
Due to their compact nature, hostas are perfect in containers. Sadly, these specimens are just as susceptible to attack. One way of deterring the pests from pots, troughs and planters is to encircle it with a band of sticky-backed, serrated copper tape – slugs and snails slithering up containers will be repelled by a tiny charge of static electricity.
Those wanting to make life easier from the start should plant hostas that are more resistant to attack. Varieties with thick leaves tend to be given the cold shoulder, as do those with blue leaves or those that are coated in a waxy layer. Vigorous forms are another good bet as they continually produce new leaves to replace damaged ones.