DON'T Presume your soil type

The soil type is an important part, in that it give a figure for the Available Water for in/in (or mm/mm). This is essentially the souls ability to store water. I had a clay selected, but I could not have been more wrong.

I did a “Mason Jar” test (plenty of YouTube videos) and my soil is basically totally sand, so my setting has dropped from about 0.20mm/mm to a new low of 0.05mm,/mm. No wonder our gardener had to add extra water to zones this summer.

It would also have a huge impact on the calculated runtimes. There’s no point in watering for an hour if a huge amount would just drain away.

This link is good


I’m going to do the soil test for sure, but how deep? I live on a hillside, and my lawn is turf with a lot of clay in the first four or five inches, then a very hard gravel sand underneath. My theory is that I should go with the turf roof layer, but I’m not sure about the hard sand (it is not very absorbent). Water will seep horizontally to some degree, and I can’t count on the hard sand for water-holding capacity since my lawn slopes both back to front and left to right, and seems to pool in the bottom right corner below the root level.

We have 100% sand fill. I started with flex daily, but had to change to fixed. I started watering once a day for a total of 60 minutes and the grass did not improve. My neighbor had a leak in one of his lines and after he dug the hole, turned on his system… the hole quickly filled with water and he turned it off.

In about 3 minutes, the hole was dry. I observed this and decided to do two waterings a day each with 30 minutes total. The grass improved a lot, but still not great. I then went to 3 waterings a day for 20 minutes each. The grass improved much more. I then started tweeking the times for each zone until I got it right.

Water drains right out of sand, so you have to water frequently. My schedule was 6 AM, 12 PM and 6 PM.