The Secret Superpower of Geraniums

The tiresome Japanese beetle has been busy doing its thing again, tormenting gardeners. The first time I encountered them in my garden I tried to look upon the Boston ivy as a greenish lace curtain draped over the fence. It didn’t work. There was no avoiding the realization that the leaves had been shredded by Japanese beetles.

Last year it was the hazel and by the time I noticed it was too late and the poor tree suffered the same treatment. There were just too many to deal with, and besides, they were out of reach. Other times these shiny brown and green beetles with locust-like appetites have appeared on my roses where at least they’re easy to spot and it’s easy to shake them off into a pail of soapy water. That’s about the most effective way to dispatch them. Sadly, for some gardeners, so many show up to feast they’d need to set up a dishwasher in the back yard and herd them in. So far this year I’ve only seen two and used the quick and simple squishing technique — ugh.

Maybe the winter was hard on the grubs, or enough lovely starlings fed well when on lawn patrol. That’s where the beetles begin their life cycle. After they’ve done eating, they mate, then the female lays eggs in a handy lawn, especially one where the where soil is moist. The following spring, eggs develop into grubs that feed on grass roots, pupate, then emerge as hungry adults in July and take off to the nearest food source, but only when conditions are right. They prefer to take flight when the air is clear, calm, humidity is high, and the temperature between 29 C and 35 C.

It’s at the grub stage in lawns where some control can be achieved by an application of nematodes, but to be effective, correct time of application, weather, and specific soil temperature must all coincide. Even then, it’s of little help if yours is the only lawn in the area to be treated.

You might be wondering why these voracious pests haven’t defoliated their homeland by now. In Japan they’re seen only as a minor pest, simply because of a difference in gardening culture. The country isn’t blanketed with lawns the way North America is, and that means far fewer places accommodate the lifecycle of the grubs.

There are traps available to limit damage, and they work extremely well, or sort of. They attract the beetles with two types of baits or pheromones, a sex one to attract the males and a flowery one to tempt both male and female. The drawback is they can attract thousands of beetles and as they pass over your garden on their incoming flight path, enough of them will stop off for a quick feed and anything else they might have in mind. No harm in trying with traps. Better still, convince all your neighbours to install a few.

The most effective solution, though not the easiest, is to gradually replace any plants and trees that the beetles are attracted to, and there are over 300 species. There are even more that they’ll never bother, and if that’s the route you choose to take, a quick search online will provide lists of both.

One
more possible way to limit the damage the beetles do, is to plant geraniums, lots of them. Research by a couple of scientists confirmed anecdotal reports that geraniums (pelargoniums) are toxic to these pests. After feeding on the flowers, the study showed the beetles became paralysed for up to 16 hours, however, it didn’t finish them off. When they recovered, they went back for more. Made them easier to pick off, I suppose, but it might take a lawn full of geraniums to provide any relief. Other anecdotal reports suggested the same effect occurred when beetles fed on flowers of bottlebrush buckeye (Aesculus parviflora), but when tested, no adverse effects were observed.

Nature does have a way of challenging us, so for now it looks like I’ll continue picking and squishing, at least until balance is restored.  

Gardens and Gardeners are Thawing Out

Robins are making an reluctant appearance and squirrels are active, so it must be Spring. But it’s a slow process in the garden. Spring doesn’t so much begin with warm sunny days; it begins in the dark, deep in the soil as the ground thaws

Sunshine may warm the top few inches of soil, enough for snow drops and crocuses, but the frost recedes more as the residual heat from the earth pushes upwards. Not until the soil reaches an optimal temperature do the roots wake up and begin feeding sap upwards. When the air is warm enough, it continues to flow, buds swell, leaves sprout and spring really arrives. And that will be another week or so.

Gardeners however, have been thawed out for some time and can’t wait to act on their plans and dreams. For many, it will be their first venture into the world of gardening, whether it’s a few containers on a deck, a flower bed, or a raised bed for vegetables.

That concept has taken off, especially among young people eager to grow fresh veggies in the backyard. Depending on soil conditions gardeners have always raised their beds above surrounding soil levels. It’s done to ensure good drainage, or simply because there isn’t sufficient existing soil in the typical backyard. Often there’s only a few inches provided to sustain grass, and not without copious amounts of water and annual fertilizing.

By raising and enclosing the bed it becomes in effect a large planter, suitable for a small backyard where space is at a premium. These are usually built with lumber, although other materials can be used. Cedar, redwood or cypress are good, though pricey choices — it’s a long payback term for a few tomatoes and carrots. Low grade lumber won’t last long before deteriorating but it can be okay if it’s only going to be in use for a limited time.

Pressure treated lumber is no longer treated with arsenic as it used to be, and from what I’ve been able to determine there are no issues with the copper compounds that are currently used,
however, I’d still be inclined to line the wood with polyethylene film. Cement blocks or old logs, though not as tidy, will also do the trick.

The bed can be any length, but a metre and a half wide (four feet) allows for easy access without having to step in. This avoids compacting the soil as everything is within easy reach for planting, weeding, or harvesting. As for depth, a minimum of 20 centimeters (eight inches) is fine, although the bed can be built much higher if the old back is getting creaky.

As for soil, regular top soil can be suitable depending on the source and consistency. Sandy soil drains quickly and has fewer nutrients while clay soil is richer and holds moisture longer, but it’s heavy and compacts easily. Both these soil types are improved by adding organic matter such as manure, compost, or leaves.

A popular alternative is triple mix. There isn’t a standard composition, but it’s typically a friable blend of regular soil, peat moss, and other organic matter. As the organic matter breaks down, the soil will settle and eventually need topping up.

Contained raised beds do tend to dry out faster than a regular bed, so watch for that. Adding mulch will save on water and reduce the need for weeding. One big advantage often touted is that the soil warms up faster in spring, allowing for an earlier start, however, keep in mind that it will cool off just as fast in fall.

Meanwhile gardeners, stay cool, real Spring will soon arrive.