Building a small water garden on a hill slopePosted on May 10, 2011 by lilian

Inspired by the great tutorial provided by Deep green permaculture on building a small water garden, I decided to

build my own.

There was an empty spot on the slope below the house, where excess water from the roof top collection was

available easily.

Observations on the site

Although the spot is located between some big trees, it gets some decent sunlight in the afternoon.

Behind the edge is a 1000L water storage tank collecting water from the roof with the exit pipe below the edge.

Although water is harvested, there isn’t any proper distribution system, only an exit pipe. In addition there

isn’t any overflow system, excess water pours down around the tank and below.

Since it is fairly humid and protected, frogs are already established in the edge.

In summer lots of wasps come look for water near the house front terrace with sometimes stinging happening.

This is a major water collecting point and a spot located fairly high on the property, so the slope can be used to

move water around.

The slope is fairly strong so this part of the property is not visited because you can hardly walk without falling.

Perma visionsPermaculture designs and ideas tocreate abundance for everyone

Permaculture functions

In a permaculture design an element needs to serve at least 3 functions.

Initially, the aim of this water garden was to reuse excess water, infiltrate it into the ground, provide visual

diversity on the site (which consist mostly of trees and grass) and create a new niche to increase biodiversity.

Having observed elsewhere that frogs eats a lots of wasps coming for water in summer, I thought having a water

garden with frogs could act as a natural wasp trap for the house and add another function.

The front of the house facing southwest is shaded by trees that provide coolness in summer, but I thought water

evaporation could also provide an extra mean to cool down the air locally.

Ingredients to build the water garden

It all started with an old cast iron bath tub that was used in the past to grow vegetables but was abandonned since.

I dug the slope to tuck it into the hill below the water pipe exit.

The hole at the bottom of the tub was sealed with compacted clay so that it would not be water tight and some

water would get slowly released into the ground by capillarity and provide a light yet constant watering of the zone

around.

Now the plants.

As described in how to build a small water garden:

There are four categories of water plants that can be included in a pond to achieve perfect balance.

Rooted floating plants, such as water lilies1.

Marginal plants2.

Submerged (oxygenating) plants3.

Floating plants4.

Image source: Virginia Cooperative Extension article, Urban Water-Quality Management:

Purchasing Aquatic Plants. ID 426-044

I first collected plants from each group:

water lili as rooted free floating plant (purchased)

Mayaca fluviatilis and Ceratophyllum submersum as submerged oxygenating plants (purchased)

yellow iris as marginal plant (collected from nearby river)

First, to accommodate frogs, rocks were added so the frogs could go up and down the water and hide from birds.

Then marginal plants were added and mud collected from a river bed was added at the bottom of the tub.

Water put back and oxygenating plant and water lili put in.

Final view after assembling everything.

Later on, I collected more plants from a local pond including water mint, water cress and more oxygenating

plants.

What’s interesting when you collect from local established ecosystem is you get some inhabitants coming as well:

Established water garden

After few weeks of sunlight and warm temperatures, the water garden already has a natural feel.

And some free floating plants have joined as well.

Stacking more functions: adding a vegetable plot

Since the water garden site in near the house (zone 1) and has both sun and water it has become a perfect site to

grow vegetables.

I then started building some raised beds on the slope around the water garden.

Raised bed is very efficient technique that requires no plowing after the initial set up. They keep the soil moist,

drained and uncompact. In my case, having raised beds around the pond also serve as a physical barrier that

prevents young childrens to run and fall into the water by mistake.

To build the growing beds, I simply used mud dugged around and some dead tree branches to build side walls.

To prevent erosion, the walls were immediately planted with french beans, sweet peas and lentils. In addition to

preventing erosion, beans, peas and lentils will fertilise the soil (they’re all part of the Fabaceae, a familly of

nitrogen fixing plants) and will give a food product.

So here we have 3 functions for each plant AND 3 plants for these functions.

Then inside the mud walls, compost made nearby was added and planted with a seed mix of water requiring

plants including lettuce, roquette, pink and black radish, spinach…

Some terrace paths were dug on the slope around to access the water garden and will also slow down and infiltrate

rainwater.

A simple log stool was added for visitors to sit and relax.

Finally everything was mulched with grass freshly cutted nearby. Grass mulch will protect the soil from erosion,

prevent water evaporation and nourish the soil inhabitants.

Final views

Here’s a photo of the site from the same point of view as photo #1.

As expected, wasps and flys are already coming to drink.

Only after a few weeks, the system already seems to be fairly autonomous and self maintaining. Now I’m waiting

for the food to grow and hope see some frogs catching wasps and flys very soon.

Perspectives

In the future, I’m considering adding more plants and shelters between the pond and the edge so toads and frogs

can move up and down and hide easily. Toads are also hiding in the edge, I hope they’ll move down to eat the slugs

and snails and protect my lettuces.

I’ve also seen a small tree nearby attract lots of cayerpillar and thought about planting one above the pond to feed

the frogs caterpillars by shaking the tree. Or maybe I’ll keep that for another fish pond…

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