beetle-water-dropLike all living beings, plants require water - and they require heat to germinate from seed, produce flowers, and mature their fruits.

In Mother Nature’s garden, heat and plenty of water create ideal conditions for the immense abundance of the tropical rainforests.

The same heat without water creates deserts, but even there the occasional rain results in an overnight transformation as dormant seeds germinate and plants rush to complete their life cycle while water is available.

Here on the West Coast of Canada most of the rain falls in the winter, and little in the summer. So the greatest show of flowers is in the spring, with plants receding underground and going dormant to reduce their exposure to the summer drought. Our native Garry Oak meadows look brown and unkempt during the summer.

The plants in our food and ornamental gardens, however, come from all areas of the world. For the most part they require the high temperatures of summer to flower and fruit, and with rising temperatures their water requirements also rise.

Our role then is to ensure our gardens have sufficient water. If we have chosen plants that are not adapted to local precipitation patterns we need to irrigate them.

Equally important and usually overlooked is the need to ensure that all the organisms in the soil have enough water! After all they are the ones who feed and protect our plants, and they are the ones who increase the water holding capacity of the soil itself.

And in Mother Nature’s garden the soil is the greatest water reservoir.

Withholding water from our gardens is exactly the wrong answer as we are becoming concerned about dwindling water supplies. It creates a downward spiral of decline, decreasing biodiversity in the soil, reducing the health of our plants and reducing the amount of water our soils can store.

Instead we need to work to increase biodiversity both above and below ground. We must beware of the single cause - single effect mentality, and manage our gardens as ecosystems.

Currently, the politically correct way to reduce water use in landscapes is through drip irrigation - delivering water directly to plant roots and not “wasting” it on the rest of the soil. This is a prime example of single cause single effect thinking.

Our garden is not a mere plant collection, but a complex ecosystem - a single interconnected organism - that needs to be managed as a whole. Plants derive their food and countless other vital organic substances from the activity of the soil dwelling organisms. Without them, they will “starve” and become sick. Sick plants become food for plant-feeding insects and microbes.

Drip irrigation was developed for situations where plants derive their nutrition entirely from fertilizers and where their root zone is restricted to a known soil volume, such as in container plant production, or food production in arid climates.

Typically those plants are grown in sterile growing media or otherwise lifeless soil. For the most part these are short-term situations, where the plants are harvested at the end of their growing season, or sold and transplanted into the environment.

There is no opportunity or intention to develop a functioning soil ecosystem.

In perennial landscapes, drip irrigation is not only unsuitable, it’s environmentally irresponsible.

Land-based ecosystems have evolved with overhead water. Soil dwelling insects and other animals depend on little pockets of water in the coarse litter layer, and microbial populations will dwindle and become imbalanced without sufficient moisture.

We go much deeper into this topic in our online course, which you can discover here:

Ecological Plant Knowledge 2 - Ornamentals Online