I put the kettle on to boil and then brought it out to the garden. Within seconds, the dandelions and thistle between pavement and path edge were melted prostrate and dead. Well- they may not be dead- weeds are resilient and tough and often have large root reserves of energy. The boiling water treatment for weeds in between cracks of pavement or stepping stones or in between rocks is the quickest and most effective solution I've ever tried for weed elimination, but it won¹t necessarily kill the weed on first try.
Boiling water makes quick history of the hardy plants trying to make a home along my driveway. In these tough little areas water is tool of choice to reduce perennial weeds. In Calgary, the perennial weeds I am tackling include dandelions, creeping bellflower, Canada thistle, sow thistle, and quack grass. While not a "selective" weed control method, the boiling water is fast, safe and pretty thorough. Two weeks after treatment, a single small dandelion sprout was emerging from one gap in the pavement so the kettle was quickly put to work again.
It's not that I am adverse to weeds of all kinds in all locations. It is just that in an effort to keep things looking clean and somewhat tidy I jump at the opportunity to employ simple solutions wherever possible and boiling water surely has to be a simple solution for tough perennial weeds.
At this time of year- somewhere between late spring and early summer - our small annual bedding plants are just finally in the ground. We may have reworked some beds, reseeded some areas of patchy lawn and topped up some poor soil areas that needed renovation. We have been enjoying perennial flowers for weeks now and the weeds have been gradually turning their toehold into an encampment in our landscapes.
New soil areas are sprinkled liberally with annual weeds such as stinkweed and chickweed and these small plants which appear so frail and tender- have stood the heaviest frosts and somehow popped up larger than the carefully selected, planted and fertilized flowers we have installed between them. If this isn't infuriating enough, some of the perennials we have been tending since spring have turned out to be the vicious and invasive creeping bellflower which came along as an intruder with a new plant from a friend¹s garden. Meanwhile lythrum (also know as purple loosestrife) which we planted ten years ago has been declared an introduced pest. Sorting out what is good, bad and pretty but invasive is trouble for new gardeners but old hat for anyone with a few seasons under their belt. The trouble is knowing how to sensibly control the problem plants without getting exhausted in the process.
Other weed control techniques include the good old fashioned mechanical methods. Your mother called this weeding or hoeing. In other words mechanical weed control means physically weeding to remove the plants. Using one of the newer garden tools such as the Circle hoe makes the job easier but doesn't eliminate the hands-on physical part of it. Mechanical hoeing does not necessarily remove a plant permanently either. The very pretty creeping bellflower (see photo) is pervasive. It's roots creep- as the name suggests- and become intertwined with all the other garden members. You may be wondering why it is necessary to control this beautiful plant at all and of course the answer is simple- leave it if you like it but remember it wants to be the entire garden. Forget about mixed perennials or seasonal colour. Once the bellflower is entrenched it is all you'll have.
As mentioned, some plants such as lythrum used to be acceptable in the garden but have now been recognized as troublesome when they escape cultivation. They are best removed before they become an environmental pollutant. Other plants are simply germinating in new soil and are destined to be short lived annuals. These seem innocuous enough until they completely take over your soil beds and squeeze out your chosen annual plants. They need to be cut off at the soil surface and bagged- not composted- for the most effective control. Still other weeds include the millions of small tree seedlings you many find beneath a mature tree. While I tolerate the occasional small oak seedling from my thirty year old oak tree and in fact seek out and dig and give away the small trees I have no patience for the many crabapple and mayday and Manitoba maple seedlings trying to take over my gardens. I look for these and dig them right away.
Weeding and weed control takes many forms just as the nature of the weed and the personality of the gardener do. It is not necessary to remove every plant growing outside its assigned boundary nor is it a rule that we have to keep every inch of garden clean from spontaneous propagators. Maintaining a balance between order and carefree acceptance of a few volunteers is left up to the individual tastes of the gardener. The sensible control with elbow grease and hot water certainly maintains the integrity of our environment better than more severe and not always more effective controls.
So next time you boil the kettle for a cuppa, save a little of the hot stuff for a problem area outdoors. In between, learn to accept a few interlopers and recognize those you'll never really want to learn to love. They can be gradually tugged and melted from your green space a little at a time.