Garden Design, Gardening, Jorge, Plants, Watering

Reducing Water Use in the Garden

Reducing water use in the garden is a no brainer as it saves both the environment and money, leading to lower energy bills. Surprisingly, for a country with supposedly so much rain, the UK’s water supply is under severe stress due to excess demand that has taken its toll on our rivers. This year, there are fears the UK could be heading for a summer drought with rainfall in April 50% below average.  To solve this problem we need to improve water efficiency and doing so in the garden can be extremely enjoyable as it requires nous and experimentation.

Create a water thrifty garden

I recently visited the Cambridge University Botanical Garden, and saw a section comprised of plants that require no watering. The accompanying material described the fascinating ways plants have adapted to arid environments, such as how species of cacti reduced their leaves to spines and adopted spherical forms as to lower their volume to surface ratio, decreasing water loss.

Scientists have identified four strategies such plants use for coping with drought: escaping, evading, enduring and resisting that is described in detail here. Put succinctly, the first two strategies involve restricting growth and reproductive activities to the wet seasons, while the latter two involve reducing transpiration and growth (often through restricting photosynthesis) as to subsist in the heat.

Various morphological and physiological adaptation have allowed cacti to be extremely frugal in their usage of water.

Your own water thrifty garden (or section of the garden) doesn’t have to be made of just succulents or cacti, but can include many familiar plants, and even crops, creating a garden rich with colour and form, but with less maintenance. There are lists of drought resistant plants online and there is great guide to designing a stunning water wise gardens that can be found here.  

Creating such a garden will involve a some trial and error, but there some general practices that can be followed:

  • Permeable paving is a must as it allows water to percolate into the soil below, feeding your plants’ roots. With non-porous materials water will sit on top and evaporate.
  • Divide your garden into hydrozones with plants with similar water needs together. This will allow you to water more efficiently.
  • By using less fertiliser, your plants will grow slower and use less water.
  • Water less, but thoroughly, watering the entire root system. You can gauge how well the water is penetrating through pushing a pipe into the soil (it will move more easily through wet soil).
  • Sometimes it can be difficult to gauge when to water. This can be ascertained by digging into soil. If the soil below the topsoil is moist, there may be no need to water. If it is dry, it’s time to water. It is important to factor in certain soils such as sandy that will feel more dry and clay that will feel more damp. Although, the ultimate measure is your plant’s leaves: darkening or drooping may indicate water stress.
  • Gauge your soil type. Some soils (clay) are better at holding moisture, and can be watered less frequently (but with more water), while others will need frequent watering (sandy soils).
  • Water in the morning and evening when less water will be lost to evaporation.
  • Dig channels, basins, or funnels to avoid run off.
  • Mulching, either with organic or inorganic materials (gravel) will help maintain soil moisture and protect soil life from the sun’s rays.
  • Forgo turf. A perfect lawn is difficult to maintain and will require constant watering in the summer months.
  • Funnel rainwater from your roofs to waterbutts. A simple modification to your guttering will provide much needed water in times of drought.
  • Much of the water your household uses is good to reuse in the garden. Greywater recycling has the additional advantage of reducing the water sent back to water companies, which sometimes ends up in rivers, destroying the ecosystem.
By far the best way to reduce water use, this simple modification to your drainpipe will provide thousands of litres of water year on year.

Hügelkultur beds

Hügelkulturs are raised beds constructed from rotten logs overlaid with organic matter and soil. They aren’t enclosed and therefore slope; henceforth the name: hill/mound (hügel) culture (kultur). Hügelkulturs can significantly reduce water use as the decaying wood acts as a sponge, soaking up rainwater that it slowly releases back into the soil. The beds are so effective that after the first year, there will be no need to water your crops for many years, provided the bed is of a certain size.

Constructing a hügelkultur is relatively simple, but they have to be of a certain height (between two to six feet). The height is important as it determines how effective it will be at holding water. In general, a six foot bed will require no watering after the first year, while a two foot one will hold moisture for three weeks. Upon construction, a bed will begin shrinking, and a seven foot bed will become six foot, so they should be constructed higher than the desired height. To avoid excessive compaction of the soil, and to maintain good aeration, it is recommended that you build your beds with steep sides (45 degrees).

A hugelkultur bed with cds to scare away birds. Picture credit: Maseltov (2005) licensed under CC-BY-SA 4.0.

Certain trees are unsuitable as some trees are allelopathic, that is, will harm your crops with allelochemicals that will persist in the soil. Others take too long to rot. Most tree logs should be fine, and there are lists of allelopathic trees and scrubs online, so do some research. Known trees to avoid include include cedar, black locust, black cherry and black walnut. Excellent species to use include alders, apple, cottonwood, poplar, willow, and birch.

Before building your own bed, it is worthwhile to decide on whether you want to construct it entirely above ground or in a shallow trench (about two feet deep). The latter, lower in a ditch, will not impose on the landscape and will be easier to construct. (Try throwing soil six feet high!) It will also save on digging, as you can reuse the materials acquired when digging the trench, and not dig up other sections of the garden. Building above ground is preferable if you already have materials on hand, or find digging difficult. Constructing on top of sod has the additional advantage in that once the plant matter breaks down it will produce nitrogen for the soil.

hügelkultur beds

Once you have decided upon the above, simply pile your rotten wood, whether it be logs, sticks, timber or chippings, with the biggest at the bottom. Then give it a good drenching. (This will aid decomposition.) Fill in the gaps with kitchen waste, grass, leaves and manure. (Adding organic matter is useful as during decomposition wood will both take in, and then release nitrogen, so it is possible that the soil may be nitrogen deficient at points.) Then add a layer of sod upside down. (You can acquire turf when building a trench. If you have none, just use soil.) Next comes more soil as so the wood is fully covered. The degree the wood is encased is a matter of preference, although anything from a few inches to half a foot works best. Finally, top it off with mulch such as straw that is traditionally used.

Now your hügelkultur bed is complete, it is recommended that you start planting to prevent erosion. (Henceforth, it is useful to construct in time for the growing season.) Over time the wood will decay into rich humus, but at first, the soil will be fairly dense, so certain crops may be unsuitable for planting in its first year. Great crops to plant in this time include members of the cucurbitaceae family such as squash, melons and pumpkins.

Jorge at PrimroseJorge works in the Primrose marketing team. He is an avid reader, although struggles to stick to one topic!

His ideal afternoon would involve a long walk, before settling down for scones.

Jorge is a journeyman gardener with experience in growing crops.

See all of Jorge’s posts.

2 Comments

  1. Hi Jorge,

    This is a really informative post, it’s obvious you’re an expert gardener.

    Reducing the need to water the garden is great for those who have very busy lives, or tend to be away from home a lot but can’t get help watering the garden. I have a friend who sturggles with this, and if I lived closer I would help but unfortunately that’s not the case.

    Anyway, thank you for sharing your knowledge Jorge, I really enjoyed the read!

    Reply

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