watering the sand between the pots in a plunge bed

Gastil Gastil-Buhl gastil.buhl@gmail.com
Fri, 01 Mar 2013 13:51:55 PST
Hi Roger,

Good to have your experienced input. This is my first plunge bed so I do expect to make mistakes. 
You are right, my coarse sand retains only 3/4 the water that finer grained sand holds. 
I measured the physical properties of the sand sold at my local store labeled 'horticultural sand' and the coarse silica sand I chose.
The results are on the wiki
The coarse sand retains only 0.23 ml/ml of water per volume sand whereas the finer sand retains 0.30 ml/ml.

The mix inside the pots has a significant fraction of the same sand. 
The contact is not as close as I think it should be. The pots are not actually normal nursery pots. 
They are baskets for planting aquatic plants, lined with window screen. 
(Actually they are in nested pairs with the screen between, an idea I adapted from another PBS member.) 
You are also right that there is not enough contact between the plunge medium and the planting medium so capillary action is not as strong as it should be.

I do have a watering wand with a fine spray but it only works with my hose. 
The city water is not suitable for my special bulbs, though I do use it on my ordinary bulbs. 
The plunge bed and bulb pots I only water with collected rain water. 
So I have to be quite careful to pour that in gently. 

That is two of you now who water between as well as in the pots. 
That is of course what nature does.

- Gastil

More information about the pbs mailing list