January in the Garden

By Russell Jordan

Is 2024 going to be a time of change in your garden or just the start of another year maintaining the status quo? Last month I touched upon the fact that it is during these dormant, winter months that there’s usually time to look at the structure of your garden and decide what is working well for you and what is, perhaps, ripe for change. The recent spell of extremely heavy rainfall, with some of the worst flooding I’ve ever seen in these parts, may have highlighted areas of your garden which need improved drainage, or where paths have become muddy and may require a total rethink. Obviously, you will need to wait for waterlogged areas to dry out before you attempt any improvements but, as soon as they do, digging drainage ditches, or installing something like a ‘French drain’, is a good winter project.
There are plenty of online tutorials regarding making French drains (named after an American called ‘Henry French’ and not the country across the pond) but the principle is pretty simple; dig a trench with a slope away from where the water collects, line it with permeable landscaping fabric (to stop the pipe from becoming blocked with soil or roots), add a layer of coarse drainage material and then lay perforated drainage pipe along the entire length, cover this with more drainage material like coarse gravel, lay more landscaping fabric over your layers of drainage material and pipe before reinstating the soil, or turf, so that the whole drainage system is invisible.
French drains can be very effective as long as there is a reasonable slope along the length of the drainage trench, and sufficient care is taken that the perforated pipe does not get blocked and has enough hardcore type material around it so that it does not get crushed—this is particularly important if it is likely to encounter any type of surface traffic.
While on the subject of waterlogged ground it’s worth mentioning a story which you may have seen recently in the news; the banning of the garden plant commonly known as ‘Giant Rhubarb’. This is one of those slightly complex situations where one species of ‘Giant Rhubarb’ was already on the ‘banned’ list due to its invasive nature; that one is Gunnera tinctoria. Then there’s a less invasive, smaller leaved, species which is G. manicata and this is the one that was originally introduced as a ‘choice’ garden plant and has, until recently, been sold as such by plant nurseries. Unfortunately this is where things get a bit more complicated!
It has now been discovered, using gene technology and good old botanising, that, at some point soon after introduction to the UK, the ‘rampant’ species crossed (hybridised) with the ‘choice’ species to produce an, almost as rampant, hybrid form: Gunnera x cryptica. What’s worse is that it’s been discovered that practically every plant that has been sold as the garden worthy G. manicata is, in reality, the hybrid form and it’s now been decided that because this form can also be invasive, to the point where it can threaten our own native flora, that it can no longer be sold to gardeners.
The ‘ban’ does not extend to destroying established plants, many of which have been a feature of gardens for over a century, but does ban new introductions and also any artificial means of aiding the growth of these plants. Theoretically, because they only grow really well where water is abundant, this could mean that if you have ‘Giant Rhubarb’ growing in your garden and you have to supply it with water, in order to keep it growing healthily, then now you must not ‘aid its cultivation’ by supplying it with water. The idea is that it will naturally die out in areas where it is not well suited and, being banned from sale, it will only remain in those gardens where it is already established and where, under the ban, it has to be controlled in a way that prevents it from escaping into the wild.
My own experience of this plant is that it’s only usually found in large gardens, the sort attached to a grand country house, and is really too big for most of us with ‘normal’ sized plots. For me the most fascinating part of this story is that the original introduction, G, manicata, is a more delicate, smaller leaved, version of what we now know is G. x cryptica and that the interloper was able to completely supplant its weaker parent without anyone in the horticultural trade even noticing. It’s only due to investigation on a genetic level, going back to comparisons with the true species growing in the wild, that this ‘under the radar’ invasion was discovered; it makes you wonder how many other garden plants are not all that they seem? To see the original report go here: https://journals.rbge.org.uk/rbgesib/article/view/1998.
Anyway, that little diversion was inspired by the recent waterlogging that we’ve experienced. Hopefully 2024 will not be one of those years with excessive rain / excessive heat / excessive anything but, in these times of global warming, it seems that extremes are something we’re going to have to deal with.
Getting back to gardening, it’s worth reminding you that whenever the winter weather is not excessively wet or cold, both of which are best avoided whenever considering garden work this month, you could be planting bare-rooted trees, shrubs and hedging. Easily obtained by mail-order suppliers, found via the internet, bare-rooted plants are generally the most cost effective means of obtaining living plants for your garden and you have, weather permitting, up to about the end of March to buy and plant them. If you have been tempted by all the various ‘rewilding’ type projects, that everyone seems to be doing these days, then planting a mixed, native, species hedge in your own garden, maybe to replace an existing, single species, hedge, could be a good start.
From my own bitter experience my main word of caution, when buying ‘off the shelf’ bare-root, native, hedging, is to avoid mixes containing ‘Blackthorn’, Prunus spinosa, which is only really important if the hedge needs to be stock-proof. I find that this extremely thorny brute can prove problematical when it comes to hedge trimming and also because any discarded prunings are very prone to puncturing pneumatic tyres. Blackthorn also has a nasty habit of suckering, often popping up many metres from the actual hedge line, and this is a major problem especially when those suckers start to invade your adjacent wildflower meadow! I’d substitute Hawthorn, Crataegus monogyna, which is a good native hedging plant but is less thorny and does not produce invasive suckers.
I hope that gives you something to be getting on with, even if in January all the gardening you actually do is to scour seed catalogues, on paper or online, from the comfort of your favourite armchair—Happy New Gardening Year.