Wednesday, 30 January 2008


I want to encourage people to use gravity to water from their tanks because it is a bad idea to substitute electricity use for water use.

The idea was to put a long, thin terracotta pot (with hole sealed) into the ground, fill it with water and plant lettuce seedlings around it, banking on the porosity of the terracotta to keep the surrounding soil damp. See original post. This pot can be refilled as required from a tap on a tank, even if it only drips out using gravity.

It has been 11 days now and here are some things I have learned so far :
  1. This works.

  2. The surrounding soil is damp enough to grow vegetables up to 30cm (1 foot) from the pot. Next I am going to plant another row of greens out at the extremity of the damp zone.

  3. On hot days the water goes pretty quickly but the lettuce stay firm. (At first I covered the whole lot with shade but removed it after a few days.)

  4. It takes a while to get used to how often to fill the pot. Keeping it full all the time is not necessary if you don't need it to be wet so far out.

  5. Growing something in the pot is very attractive and means there is more food grown per area. If not growing anything in the pot then I would use a lid to reduce evaporation. I have recently put another creeping plant in the pot to reduce evaporation but, on the other hand, this will use a little bit of the water.

  6. The rate of growth of these lettuce has been at least double that of other seedlings I planted in another place at the same time, with a drip line.
  7. Having the thin drip line dripping into it once a week (that is 2 litres) is not enough to keep it full but may be enough for the lettuce - if I didn't have the water spinach in the pot.

If you have a tank this would be a great way to make use of the water without a pump.

If you are using mains water it fits in with the regulations beautifully as you are allowed to fill up a container any time you like.

I am thinking of setting up a whole line of pots connected with 13mm (or even thinner) tube and having them as the basis of watering soft summer vegetables, such as lettuce, cucumbers, even beans. It is similar to Scarecrow's wicking system and a little less labour-intensive. Also excellent in small places.

This pot was $10 from Bunnings but I would look out for something similar in discount shops or garage sales etc. The walls are very thin - I am not sure if this is necessary or not. I wanted a deepish one that was narrow at the top so it didn't use up too much space and didn't evaporate so much.


Mary C. said...

About how much of a radius of earth is kept moist by your terracotta pot? Do you think one would work well to service a whole 4x3 bed?

Kate said...

Hi Mary,In Adelaide you would need 2 in that area I would think. As I do not know your climate, you would have to experiment. They are very effective and have been adopted by several other blog readers around the world.