How to use gypsum

Drainage isn’t one of our strengths around here. We’re on good ol’ Sydney clay, and if you fill up a puddle you could probably take a short bath.

So in Bed B which is against the south side of the house, many things struggle. During Winter, when it gets almost no sun at all, I get moss growing on the surface.

This year I used the winter season to grow a green manure crop in this bed in an attempt to improve the soil with organic matter, but it hasn’t done much for the drainage issue – that layer of clay is still there, about 30cm down.

Bed B before the gypsum

So the obvious way to go is raised garden beds, but I’ve invested quite a lot of money already this year getting the fruit trees established and stocking my seed supply. The materials for raised garden beds are quite expensive if you don’t have stuff on hand to repurpose.

So for Bed B and the fruit trees bed (both unraised), I thought I’d give gypsum a try.

Now I’m really the last person who should be writing a ‘how-to’, seeing as this was the first and only time I’ve used it, but here goes.

Gypsum is a naturally occurring mineral that is used in the garden to break up clay soils. It improves the soil structure and therefore increases the drainage. They use it in the manufacture of plaster of paris, and the texture was reminiscent of that.

The instructions indicated that I should use between 1 and 2 kilos per square metre, and I bought a 25 kilo bag. That was about the right amount for the area of both beds.

I scattered the gypsum by hand over the area and raked it in lightly. If the soil is particularly dry you should water it in  little, but I figured that the rain should do the trick over time.

I did this about 2-3 weeks ago now, and I can’t say I’ve noticed any major difference yet. I hear that it is a slow process, but it will eventually work well. I will need to repeat the process yearly over three years, and I should see a big difference.

So I might add that to my yearly treatment schedule for Bed B during winter. 1st step green manure, 2nd step gypsum.

No more baths!

So now the bed is ready for its summer schedule. I have grand plans for pumpkins, zucchini and squash.

It’s your time to shine, Bed B.