How to get rid of pests in your garden for good, from slugs to squirrels
After recently putting a beautiful tray of carefully grown plug plants of Daucus carota outside my greenhouse to harden off before planting, I was dismayed to find the burgeoning seedlings shaved to the ground. Ruddy rabbits.
Lesson learnt: I will put the trays up on a table next time.
A lot of fun was poked at the RHS recently for its reclassification of pests as “garden visitors”. But whatever we call the creatures that munch their way through our food crops, dig up our borders or destroy our young trees, gardeners do need to control them.
The way forward is integrated pest management: a combination of physical (squashing, netting, squirting etc), biological, chemical and cultural methods to help you grow the best crops. This will involve using techniques such as breaking up blocks of one crop, encouraging beneficial insects and, most importantly, watching over your plants, so that as soon as a pest arrives you can sort it before it becomes a big problem.
I have noticed that after 50-odd years of gardening, I am now attacked on more fronts and with more volume than ever before, as new pests and diseases arrive.
Take wood pigeons. They used to visit us in quite moderate numbers, and I enjoyed their soothing call. Then a ban on shooting them was introduced in 2019, so the local gamekeepers and farmers let them be; and now the sky is thick with them. My imitation hawk hanging on a string is no longer a deterrent to them, but rather, I suspect, a source of mirth.
Or take the flea beetle. Oil seed rape is not grown in our area now because of changes in the law with neonicotinoid use, so instead of the beetle being drawn to the hundreds of hectares of pretty yellow rape flowers that used to grow, the sky-high populations now visit my brassicas instead.
These voracious feeders pepper the leaves like gun shot and scoff radish, broccoli, cabbage, turnip and more. My neighbouring tractor driver said the air was thick with them when he ploughed. Previously, upping the humidity (by covering plants with polythene or fleece) was enough to deter them; but last year my fine mesh struggled to work as I must have inadvertently left a few gaps.
Anyway, here’s a guide to various pests you may have to contend with: how to live with them, or do away with them, as appropriate.
Badgers and rabbits
Since 1992, badgers have been protected in the UK. Their only predator is the motor car. Badgers regularly made nightly visits into my garden, stripping out the woven hazel cladding to my raised beds to feast on the slugs and snails harbouring there.
They dug up the lawn for earthworms and the borders for bulbs, so I hastily put up an electric fence around the garden perimeter. It consists of four electrified wires with the top wire 30cm high and the others at heights of 10cm, 15cm and 20cm, fixed to wooden posts around 10m apart, and runs off the mains. It is unobtrusive, relatively cheap and totally solved the problem. It also stopped the rabbits – until our Jack Russell started to bring them in from the meadow.
It does require maintenance, such as keeping grasses and fallen branches from shorting it, so I glyphosate a narrow strip along its base a couple of times a year. Embarrassingly, the week after it was installed, as I walked through our village I met a neighbour who complained of suddenly being plagued by badgers – they had discovered new territory.
In woodlands, deer (roe, fallow and muntjac) can devastate young and newly planted trees especially. Some will just lift out these small trees or browse the growing points. The damage is recognisable as the damaged plants often have frayed ends, as the deer partially bite through them and then tug.
Peter Glassey, head forester at Burghley Park in Stamford, looks after more than 3,500 trees and is always planting new ones. Depending on the size of the planting, he works out if he needs to put individual tree guards on. He points out that deer alter the ecology of the woodland, eating lots of the lower-storey herbs and flowers.
Even if you have not got young, vulnerable trees, deer will devastate many garden shrubs, and when food is scarce they will nibble at many plants. Roses seem to be like caviar to them. Richie Steffen, executive director of the Elisabeth C Miller Botanical Garden in Seattle, has some useful strategies. He finds Plantskydd repellent effective and uses it as a liquid in late winter/early spring, then sprinkles the granular form around any nibbled plants in the growing season.
“I think the key to limiting damage is to apply early in the season as deer start to sample plants around the garden, keeping application regular early on, then as needed later in spring and summer,” he says. “If you can teach the deer early on that the garden is not a good tasting salad bar, they learn to find other places to eat and come back to sample less often.”
Deer are shy creatures, so planting near the house tends to be less vulnerable. Many have told me that stale human urine, preferably from meat-eating males, is also an excellent deterrent, so this could be the most carbon-neutral and pocket-friendly option to try first!
Moles are amazing – a Jack Russell of ours brought one into the house and it escaped down through a narrow joint in the old brick floor in our dining room, leaving just a pile of earth on the bricks and an extremely confused dog not believing what it had seen.
Moles come into the garden hunting worms and grub populations – they can eat their own body weight in these on a daily basis. I tend to just kick the soil heaps and turn a blind eye, but every so often the numbers explode, usually in spring and early summer, so I use a mole trap.
John Finnemore is an expert trapper and on his website he explains the best ways to employ traps.
Box moth is creeping up more in this country and many are concerned about the degree of devastation it causes. It seems that the best products that have been approved in Europe are not approved here, although they are available on the internet.
Didier Hermans, a Belgian grower, has spent many years breeding the excellent box varieties that are resistant to box blight (I grow his ‘Heritage’ variety). He explains that Bacillus thuringiensis (XenTari), a biological agent that works against young caterpillars, is the main product used in Europe. This has not been approved for use for the retail market in the UK, but Topbuxus is hoping to get approval shortly. You can use DiPel now though, which is almost identical – however, if you have not got your PA1 and PA6 spray exams, you need to use a qualified contractor to apply it.
This works for quite a long time and is safe for beneficial insects and other animals (and humans). It is best sprayed in the evening if flowers are nearby.
The best time to treat is April, July and the end of September (if you treat at the end of September, you don’t need to do anything in April because all the winter caterpillars will have cleared).
Slugs and snails
These were for many years the top garden pest for us on Gardeners’ Question Time. They start to appear on Valentine’s Day, so early control is needed. When I started my veg patch, if I went out in the evening I could literally hear the slugs chomping on my patch of onions! Since then, I have definitely got on top of my populations.
To start with, I laid a length of flattened copper pipe along the outside of my veg garden: copper is a good deterrent, but the pipe needs to be 4cm wide and of a good-quality copper. To reinforce the line I add used coffee grounds, which have been shown to be effective.
I also use ferric phosphate slug pellets spaced about 6-7cm apart, and I choose ones that contain a fungicide as otherwise they go mouldy and are useless. The blue colour is purely a dye to deter birds. I put them around newly planted-out plants initially, when they are extremely vulnerable. I monitor the damage daily, and if they have not been munched I need not reapply; otherwise I add more.
You won’t find dead slugs with these as they go underground to die. If you have dogs, be aware that dog toys can be magnets for slugs and snails, which carry lungworm that can be transmitted to dogs and is really nasty, so do bring in your dog toys at night.
Having planted more than 2,000 trees as a shelter belt around my garden (including on odd patches on my friendly neighbouring farmer’s land), I totally transformed the habitat from squirrel-free arable/grazing land to squirrel-abundant woodland. These are grey squirrels, of course, and do much damage to my trees. They also like to munch on my root veg and, of course, devour several types of bulbs, especially tulips.
You can use cayenne pepper around tulip bulbs to deter squirrels, which I found highly effective, but apparently the squirrels can get it in their eyes, which they then rub, so their eyes can become highly inflamed.
A year ago I installed a gas trap, the A18 from Good Nature Traps (£169), which is approved by DEFRA (Department for Environment, Food & Rural Affairs) and APHA (Animal and Plant Health Agency).
This despatches the squirrel instantly with a strike to the head, and there is enough gas in the canister to sort 18 before it needs replacing. It is important to install the trap before you provide the squirrels with an abundant food source (i.e. tulip bulbs, hazelnuts, etc), otherwise they will go for these rather than the trap.
If I had red squirrels anywhere nearby, I would not employ the trap. I have had amazingly good results with this and highly recommend it.
Rats and mice
These, too, seem to be on the increase. My greenhouses are the number-one target, as they are warmish and usually full of tender shoots. I monitor daily, as when you think you are on top of the situation and your back is turned, another invasion takes place.
I sow all vulnerable seeds up on a platform with an overhang (a wide bit of wood on two upturned pots) which is foolproof. I do back it up with some mouse bait or traps too, for other susceptible plants on the ground.
The problem with many of the biological controls that are being used extensively in the commercial market is that they have not been approved for the retail market. This is because most are classified as skin irritants, even though many are not (it is assumed that commercial operators are wearing proper protective clothing, and that domestic gardeners are not).
So many of the products your garden centre stocks are inferior to better and safer ones on the commercial market. If you take your PA1 and PA6 spray exam (a simple and inexpensive two-day course and test, which I have done), you do have access to many more superior products. Alternatively, contractors qualified to use the commercial ones can apply them for you.