August in the Garden By Russell Jordan
H
aving begun last month’s article with musings on how important the weather is, to what’s going on in the garden, I am currently even more obsessed than usual due to the ‘Met Office’ warning, for dangerously high temperatures, that is in effect as I write. I’m hoping that, by the time you are reading this, there has been a period of summer rain and a return to more seasonably average temperatures. Although the best way to reduce the need for any artificial irrigation is to plant according to the ‘right plant, right place’ principle, in times of extreme heat and drought watering to keep plants alive is unavoidable. Watering overnight is best simply because less water is lost by evaporation and more of the precious water gets a chance to penetrate the soil. Also, there is a danger that if you water plants in hot, sunny, weather then the foliage can be damaged by the action of the sun on the wet leaves. Remember that a good, long, soak is far better than just a quick sprinkling with the hose because the latter promotes surface rooting and this will make plants more prone to succumbing to drought in the future. Damage due to lack of water may not show up immediately, especially in more woody plants, but the stress of being droughted can make plants more susceptible to succumbing to pests and diseases even once ‘normal’ weather conditions have returned. The main consequence of being stressed by lack of water is to speed up the process by which flowering plants finish flowering and set seed. They have evolved in this way as an attempt to ensure that if the drought is severe enough to kill the parent plant then, at least, if it’s completed flowering and managed to produce viable seed then there will be a new generation to take over once more favourable conditions have returned. Seed is designed to remain dormant, but alive, over a long period of time, centuries in the case of some plants which have germinated having been discovered by archaeologists, which is the ultimate insurance policy to guarantee the survival of plant species. This brings me back, nicely, to the wildflower meadow area, an ‘inoculation patch’ within a larger field, that I sowed in the spring. I did, as ever, leave it a little late to get started with this new area of meadow but the inoculation patch was initially mown off, ‘cleaned up’ with an application of non-persistent herbicide (glyphosate) and the resulting bare circle scarified to open up the soil surface. Although, prior to being killed off with the herbicide, the original vegetation was predominantly italian rye grass (a non-native, ‘alien’, agricultural grass
30 The Marshwood Vale Magazine August 2022 Tel. 01308 423031
cultivar) with associated agricultural weeds, largely docks, it is interesting to see what has happened to it now. The ability of seeds to remain dormant, but viable, until conditions are ideal for germination creates what is known as a ‘seed bank’ in any soil where plants have ever grown. One factor that may break the dormancy of seed in the soil is the removal of any vegetation that has, up until the point of removal, shaded the soil and prevented dormant seeds from being exposed to light. Breaking up and turning over the soil will also bring dormant seed to the surface where the exposure to light and air may be the factors that break its dormancy. The addition of moisture, plus spring or summer temperatures, may be the final part of the jigsaw which unlocks the germination process of seeds which have been dormant in the soil for decades. The relevance of this, to my newly sown wildflower meadow, is that at this point, about three months after sowing, some of the wildflowers are in flower (poppies, cornflowers, ox-eye daisies etc.) but the predominant species, which outnumbers all the newly introduced wildflowers, are annual thistles—‘Sow Thistles’ to be exact. The interesting thing about this is that, in the whole of the rest of the field, there are no sow thistles to be seen. They cannot compete with established plants but, in my inoculation patch, as soon as the competition is removed and the soil surface broken up, then the thousands of thistle seeds, which had been dormant for years, break their dormancy, germinate, grow and, in a matter of weeks, mature to flowering size. Soon they will set seed themselves to add another generation of thistles to the seed bank where they will wait for another time, maybe many years in the future, when they have the perfect conditions to germinate. The other weed species which is worryingly abundant, having germinated from the seed bank, is the common dock. Docks are present in the existing field mix, they are very difficult to eradicate, so to have large amounts of their seed in the exposed soil of my inoculation patch is not unexpected. What is concerning is that, unlike the annual thistle species, docks are perennial and once established they are very difficult to get rid of and could potentially ruin my planned wildflower meadow due to their ability to out compete everything that I’ve introduced. If I use a selective herbicide, one that kills broadleaved weeds in established grassland, this will also destroy all the wildflower species which are even more susceptible to weed
