Gardening: When water retention isn’t a bad thing. And how to make a rain gauge.

Let there be work, bread, water and salt for all. – Nelson Mandela

Photo: Andrew Rollinger, Flickr ccl

Water—that commodity upon which the foundation of all life on earth rests. In recent years we have been warned of a looming water crisis. Large scale impact on the issue is best dealt with by national and international policies. But that does not mean individuals can have no impact. There are micro ways to better manage our water consumption, and one of them is if we garden. A small thing yes, but as water drops can form an ocean, every little bit counts. 

Water management will benefit not only your gardens but you. You can significantly reduce the amount of time you spend working in, as opposed to enjoying, your gardens. Gardens need a constant source of moisture to flourish, so can contribute greatly to our overall water use. All that watering not only uses a precious resource but also uses your time.

Halifax Public Gardens. Photo: ndh, Flickr ccl

What do I mean by garden water management?

What I refer to is water retention in your soil. If you have proper water retention, your plants will have more nutrients available from the water and you will use less water for the same amount of benefit.

By ensuring optimal water retention in your soil you will benefit the plants and also reduce your need to artificially irrigate your gardens (drip hose, spray, etc.). You get the same garden results with less water use.

What is water retention in gardens?

Water retention is the rate that your garden soil retains/looses moisture after becoming wet. If you have too little water your plants will either wilt or grow stunted; if you have too much water roots are more susceptible to rot. You need optimal mixture of drainage and moisture retentive material to have maximum benefit from whatever water your garden receives.

Halifax Public Gardens Bandstand.
Photo: Kelly Mercer Collection, Flickr ccl

How to check for water retention

You need to find out how fast your soil drains after rainfall/watering, and amend as necessary. 

To check retention water a portion of your garden thoroughly. After 2 days, dig a 6” deep hole and check the soil. If your soil is somewhat damp at the bottom of the hole your soil is reasonably water retentive. 

If it is dry, you may need to work organic matter into your soil. Organic matter (dead leaves, compost, etc) retains water when it is suspended throughout your soil. 

If it is wet, your soil may need a lower ratio of organics to drainage material. Drainage material, such as sand or very fine stone, allows water to leech away and the ground to dry out more quickly.

The majority garden plants require a constant state of some level of moisture for optimal growth.

Different plants have different water needs

Uniform water retention is not necessarily a good thing. Plants require different moisture levels as much as they need different amounts of light.

Some perennials thrive in moist soils; other detest it. Delphiniums, jack in the pulpit, astilbes, Japanese primroses, lupins, ferns, sambucus and monkshood all benefit from high moisture retentive soil.

Drought tolerant perennials prefer to dry out between waterings. These include salvia, lavender, Russian sage, lewisia, thyme, potentilla, phlox and many more.

As always, when purchasing or planting from seed check the characteristics your plants need for optimal growth. Then plant in a suitable site with suitable soil. Every garden has varying soils, unless you had all your ground trucked in.

Homemade and purchased water
gauges. Photo: mulsanne, Flickr ccl

Make a Rain Gauge 

Remember, Mother Nature tends your garden too. Track how she is doing with a rain gauge. Be more aware of the rainfall in your garden. It may be completely unnecessary for you to water your garden.

Either purchase, or make, a rain gauge. Making a rain gauge is actually quite easy. Install it (purchased or not) in the open where it won’t be affected by runoff from overhanging plants or structures. 

You will need a ruler, a straight sided clear jar or plastic bottle, something to make it stable (either a block of wood, rocks or a stake in the ground) and some rain.

1. Make sure your rain receptacle has straight sides. If the top curves in the measurement won't be accurate.

2. Set your measurements on the receptacle. Attach a ruler to the jar so you can measure the amount of rail collected. Alternatively, you can draw measurements right on the jar with a permanent marker.

3. Make the rain gauge stable. Depending on your chosen jar, attach in an appropriate way to make it stable. If it's plastic you can screw or nail it to a post; if glass glue it to a block of wood or similar to prevent it from falling over, or it could be wired to a post or stake. Use your imagination, just as long as it won't fall over.

4. Wait for rain, and then write down the rain amount in a journal.

You can track per rainfall, or week, or longer simply by writing down the measure of rainfall. As I said above, you can draw your marks directly ON the rainfall “catcher” if you don’t want to use a ruler. But your hand drawn divisions won’t be quite as accurate. 

I would suggest getting a 6” plastic ruler from a discount store. You could also get a more stylish container than a jar or pop bottle, as long as it has straight sides and can be attached securely to something so it won't tip over.

Note: The photo above shows a pop bottle with rocks in the bottom and the zero mark starting above them. I highly doubt the accuracy of that method as the rain would have to fill the spaces between the stones before making its way up the gauge. You could fill with sand, but it would have to be packed pretty tight to avoid rain from seeping in. Or before you expect rain fill the bottle up to zero mark with water. Who wants to do that?

There are ways to accurately use this method, though a little complicated. For example, pour 1" of water in the bottom before putting in the rocks or sand, measure where the level is after adding the rocks or sand, mark that point as 1" and  start your further measurement divisions from that point up.

One final note about watering

Never water your garden from above at any time of day. Overhead watering wastes water and encourages the spread of plant diseases on upper portions of plants or on their neighbours. 

A common myth is that water droplets can harm leaves by acting like mini magnifying glasses and cause burning. This myth has been around since the mid 1950s. Studies have found that the water droplets evaporate long before being able to generate enough heat to damage plant leaves.

This myth really doesn’t make any sense. Think of a gentle June rain shower, followed by the sun bursting through the clouds. If nature allows it, and plants are still surviving, it can’t be true. But it's been around for decades.

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