Urban Food Garden

Hydra Zoning

Unless you live in an extremely high rainfall area water is going to be an ongoing issue for you if you are to maintain a food garden.  To maximise water use efficiency it is a good idea to group your plants into water zones, depending on their water needs, collectively called Hydra Zoning.

Why grouping plants into water zones is important

When planting out a garden many people do not consider the water needs of their plants, often putting plants with both high and low water needs side by side.  If you do this then to provide the right amount of water you will have to water each plant individually, which is very time consuming. If you water them as an entire section you will be either over watering plants that don’t need much water or under watering those that need a lot.

So it is a good practice to group plants together that have similar water needs as this makes it easier for you to supply the right amount of water to them. This is best done by grouping them into separate water zones.

water zones

There are three basic water zones.  They are: –

DRY ZONE

LARGEST AREA:  For plants that need no watering at all except when first planted. This area is usually the largest area.

IRRIGATED ZONE

MEDIUM SIZED AREA:  For plants that need to be watered when the weather is hot and dry.

WET ZONE

SMALLEST AREA: For plants that need to be in water or boggy ground. As wet zones use a lot of water they should be by far the smallest area in comparison to the other zones.

Working Out The Sizes For Each Water Zone

How big each water zone is will depend on :-

  • THE ANNUAL RAINFALL IN YOUR AREA
  • THE TOTAL SIZE OF YOUR GARDEN
  • THE NUMBER AND SIZE OF YOUR WATER TANKS
  • THE SIZE OF THE ROOF/S THAT THE WATER TANKS ARE ATTACHED TO
  • THE COST OF MAINS WATER

Working this out can be difficult, but you will know if you have the balance right if you do not run out of tank water by the end of Summer or if your water bill is not too high.

Multiple Water Zone Areas

Of course it would be unlikely that you would divide your garden up into just three water zone areas as this would be impractical.  I have multiple water zone areas throughout my garden, some as little as just a few metres square while others, usually the dry zone areas, are quite large. 

These water zones are best applied in conjunction with a Garden zone plan, for more information see: Garden Zones.

DRY ZONE EXAMPLE:  This part of the garden is devoted to Australian native trees and shrubs; it is never watered except when replacement plants are added.  Australian native plants are ideal for Dry Zone sections as they are more used to Australia’s harsh dry environment, though note that there are many native plants that do have high water requirements and therefore are not suitable for Dry Zones.

IRRIGATED ZONE EXAMPLE:  Vegetable beds, berry bushes and most fruit trees will require some extra water during the warmer months to produce good crops, so they should be placed in Irrigated Zones.

WET ZONE EXAMPLE:  This bathtub pond is in a hollow, when it heavily rains it naturally fills with water.  There are bog plants next to the pond with Dry Zone shrubs on the slopes.

WET ZONE EXAMPLE:  Bathtub pond in my greenhouse with Kang Kong and water chestnut growing in it.  As well as growing water loving plants this pond serves as a humidifier in summer and a heat bank in winter, storing heat in its water during the day and slowly giving it off at night.  The heat it gives off at night protects the inside of the greenhouse from frosts even in the coldest winter nights.

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