|Porous clay pots or ollas: I’ve been using these for tomato plants for a years now with great results. It's ten times more efficient than surface irrigation because the amount of water used is largely determined by how much water the plant is using. (“It’s almost like an intravenous line for a person,” says David Bainbridge in his book Gardening With Less Water.)I generally only need to fill the ollas once a week (twice in extremely hot/dry weather).An added bonus is that weeds are reduced, as are pests and diseases- the plants don’t get stressed, and water is kept well away from leaves and stems.|
Porous clay pots were used this way in China 2,000 years ago, and have also been traditionally used in drylands across Latin America (where they are called ollas), and from the Middle East through to India.
1. Collect terracotta pots (as large as possible- the smaller they are, the more you will need). They must be unglazed and unpainted. Used pots with small cracks are OK.
2. Plug the bottom holes using a cork or sealer/glued on pebble/wax
3. Loosen soil across the bed, and bury pots where needed. Keep the rim poking above the soil, put a lid on and fill with water.
4. Leave overnight to see how far out the water seeps- plant your seedlings in this zone (usually within 10cm of pot). A 25cm pot might water 3 tomato plants – but leave room so you can reach the pots for watering once the plants grow.
5. Refill pots as needed- at first, they should last a week but as things dry out they may need filling every few days.
See ollas in action at Kāpiti Community Gardens: Matai Rd, Raumati; Paekākāriki School; Te Newhanga Community Centre Paraparaumu. Matai Rd. has a self-filling valve system runnning from a barrel.