It has been and still is a hot dry summer. Before we left for our holiday I handed over the watering and walked through the garden pointing at plants that I liked to survive and ones that could be sacrificed. Our water butts with a capacity of over 4000 litres were all empty. The last 1000 litre had just been put in the pond and although we have a few smart watering systems (more below), especially the new plants depended on manual watering.
The garden and the issues caused by the drought (and the climate change causing the heatwave – not great holiday thoughts) stayed at the back of my mind. While holidaying I reread Beth Chatto’s book on drought resistant planting and researched a bit further. As such I have come up with a plan for my own garden and my deliberations may well be useful for your garden too. I have divided these in six main categories: planting, soil, pots, lawn, water butts and irrigation systems.
Planting
After the first year of planting any plant should be so established that it doesn’t require watering unless it is very, very dry. If like me you had a few specimens that looked sad already in June and needed continuous watering, those are candidates for replacing and/or moving to a wetter/more shadier part of the garden. I love the flowers of phlox, but compared to geraniums, scabious and roses, they were continuously on the brink of dying, requiring watering every day. Roses also need watering in order to flower well, but as their main flush of flowering is in June and they have deep roots, they just need a bit of topping up.
The list of flowers that did fine is luckily larger than the list of the ones that are going to be replaced, in my garden at least. Erygnium (sea holly), salvias, delphiniums, kniphofias as well as some real drought loving plants like rosemary, lavender, sedums and Mexican fleabane all fared well. Hydrangea Annabelle didn’t quite enjoy the drought, but did just as well as previous years until about mid-August. I’m hoping that it may just go dormant a bit earlier than usual.
As we always have dry summers in Cambridge, and sadly climate change means that summers will only become hotter, it is also good to aim for a planting scheme where the soil is covered by plants and the sun doesn’t shine directly on the soil, drying it out. While the plants are growing into their space, use a mulch to cover the soil and have this in place by April. Also try to plant any new plants by April, or plant late summer so they have the winter to establish.
Soil
The largest potential reservoir of water in any garden is the soil. In Cambridgeshire we are actually very lucky to have clay soil. Oh, I know, on wet winter days when digging, or when I can’t walk to the compost heap unless wearing wellies to conquer the mud, I don’t enjoy the heavy soil either, but it is fertile and from all soil types it does retain the most water. To allow plants to grow and to make the most effective use of its water retaining abilities, we need to add organic matter. Lots of organic matter. Some parts of my garden only became workable after I had worked in about 15cm of compost.
Most plants don’t like to be in waterlogged soil and by adding organic matter (compost, soil improver from the waste facilities in Waterbeach, woodchips, etc.) you improve the structure. Clay particles are very small and as a result there are very small spaces between the particles and water cannot get out. By adding larger particles, the water drains. Of course, by adding compost you also improve the chemical (minerals) and biological (bacteria and fungi) quality of the top soil which your plants enjoy as well. From a watering point of view, once your plants are in a well-structured soil, they can put their roots deep down in the water retaining clay while enjoying all the qualities of the topsoil.
Capillary rise is another reason for improving your top soil. Capillary rise can be explained as follows. When you put a thin layer of water in your bath and you stand a sponge upright in it, then the top of the sponge will be full of water after some time. That is capillary rise and that’s what you’d like your soil to do as well.
Now due to the small spaces between the clay particles, clay itself has absolutely rubbish capillary rise, demonstrated by the cracks that easily form in the summer in clay soils. If like me, you see a few of these now in your garden, then you need to take action. The solution is simple. Just add organic matter. You can simply put it on the top and earthworms will do the rest. You can easily buy large quantities but it doesn’t have to cost the earth either. If you have the space, start composting and if you do any pruning or strim a hedge, shred the trimmings and just put those on your soil. (But never put any diseased material on your soil, put that in your green bin).
Of course not all soil in Cambridgeshire is clay. It is not homogeneous due to the historic landscape of meandering streams and rivers (riverbeds). Soil variations exist even in relatively small gardens and soil quality is also strongly impacted by past human activity. Capillary rise is hindered by building rubble and also garden foundations, like sheds, garages, paths, fenceposts etc. We even found the old cespit in our garden. If you find that in an area plants just don’t take despite having improved the soil, it’s time to go on an archeological mission and see if you can remove what is causing this.
Capillary rise is of course what you want until the last inch or so. You don’t want your precious water to evaporate in the sun’s rays and that’s where mulch or ground cover plants come in. A bark mulch has too large particles for effective capillary rise and as such it prevents the water from rising to the top.
Pots
There is no garden without some pots. I have them dotted around the garden and although I can organise them a bit better, I wouldn’t want to do without. For years now I have successfully used a water irrigation system for the pots on the patio. It runs on a timer which can be adjusted according to the weather. It usually is on for only five minutes each day. By watering little but often the soil doesn’t dry out and the water doesn’t run off like it would on a dried out sponge.
The above leads to very effective watering in combination with the following:
- Plants that need regular watering are only planted in large pots, at least 20 litres but preferably more,
- Smaller pots get planted up with succulents which don’t need regular watering. Succulents are fabulous plants; most produce amazing flowers and the range of succulents is simply amazing,
- All pots have a container inside, at the bottom above the drainage hole that will keep some water. I use butter tubs, take away containers, mushroom containers etc. In this way excess water will be absorbed by the plant, but too much (ie in winter) can still drain out. It’s a DIY version of a self-watering pot. If they don’t have such a container inside, I use a tray to catch any excess water.
This year I set up a new solar powered irrigation system called “Irrigatia” for my tomato plants. It works really well and I may set this up for the potted mint collection too next year. I already use a few self-watering containers in the vegetable garden and maybe I should buy a few more.
Just note that if you would like to install a water irrigation system with a timer for pots, buy all the materials by April latest as every summer they are out of stock.
Lawn
Grass’ main defence against both drought and being eaten lies within its strong roots. Even if munched down to the bare soil, it will come back. It applies the same tactic when it is dry. It will readily give up its foliage and wait for better, or rather, wetter times. A lawn that consists of yellow straw will spring back to life after enough rain has fallen. Other plants that grow in laws usually stay green longer. You may not be charmed by dandelions, but some “weeds” like self-heal and clover can be quite pretty and are good for wildlife too. I personally think that all lawns benefit from clover. It is easy to mow and keep low, it stays green longer than grass and fixes the nitrogen in your lawn, as such fertilising your lawn which means it also stays green longer. There are special grass mixtures with clover seeds in them.
Water butts
Water butts come in all sizes and costs. As we have a wildlife pond which is best topped up with rainwater, we invested in two 1000 litre tanks. One we placed at the bottom of the garden and as the garden has a slight slope, we can syphon the water from the one near the house to the one at the bottom of the garden. It takes all night, but it works. Two autumns ago I put water butts onto every single roof including every shed that we have. It was a bit of an investment, but then I have perfectly good water butts that are already twenty years old and I expect these to last just as long. The advantage of having so many water butts is that there is always water nearby, at least in “normal” summers.
This spring I realised that I could add another two water butts and with those in place we now really do capture all the water that we can and the focus needs to shift to using the other reservoir: the soil. I already did fill all my watering cans when it was raining, but I can certainly maximise this by emptying water butts into the flowerbeds when forecasted rain is going to fill them up again.
If you attach your water butt to a downpipe from a large roof area, it may only require one centimetre of rain for it to be full. One centimetre of rain is not enough for your (new) plants to be properly watered, but if you add what’s in your water butt, they can probably last another couple of weeks again. It’s a slightly strange take on “saving for a rainy day”, but I think it will work.
Irrigation and other smart watering systems
Having stated above that established plants shouldn’t need any watering especially when you have improved the soil structure, for newly planted areas and pots, an irrigation system may greatly reduce your time spent watering. You probably have to use one of the following:
- Soaker and sprinkler hoses: good for establishing new lawns and new flower borders, but otherwise very wasteful
- Drip hose: good for establishing a densely planted up area like hedge, but not good for other situations. The “drips” are often spaced out quite a bit and often miss the plant so you have to have it on for a long time to achieve the same effect as a soaker or sprinkler hose would do. You also end up with a lot of hoses to water a relatively small area
- Sprinklers: Oh the joy of continuously moving your sprinkler so you water the whole area, need I say more!?!
None of the above will work with a water butt by the way. And yes, I tried. To get these systems to work mains water pressure is required.
As mentioned above, self-watering containers and watering systems using either a timer (which can be attached to a water butt or an outdoor tap) or the Irrigatia system that comes with a solar powered pump work well and are efficient. (The Irrigatia system would benefit from better written down instructions unfortunately and also only buy timers from reputable brands. You want a reliable timer if you put in on your main watering system to prevent it from breaking and thus being on all the time.)
For greenhouses I can recommend olla’s (buried terracotta pots that you fill with water which then seeps through the pot) as long as you plant very closely to the olla, as well as watering trays with capillary matting linked to a container with water. The latter will only work if you ensure that the plants are higher than the water container and the capillary matting isn’t exposed to the sun. I tend to cover empty spaces with rocks or empty pots as otherwise the water just evaporates from the surface of the capillary matting and dry capillary matting is useless. Ollas and capillary matting of course also work outside.
Drought and watering plan
The aim of a good drought and watering plan is not just to save time and money, but also to make a garden more environmentally friendly. Healthy plants will support more wildlife and capture more carbon.
If you would like some help with putting together a plan for your garden, please don’t hesitate to get in touch.