Lowering pH of Soils Information

I had the opportunity to hear Kevin Handreck speak about soils at the Australian Plants Society Flower Show and Plant Sale. Kevin is a well respected soils scientist and author of a number of small books for the CSIRO. He also wrote the book ‘Gardening Down Under’-Better soils and Potting Mixes for better gardens. I highly reccomend this book to all gardeners.

Instead of speaking in general terms about soils, he asked the audience what they would like him to discuss. Well! My first question was about dealing with highly alkaline soils. Bless the man, he spent quite a while discussing strategies.

As Kevin said, the obvious solution is to use those plants that don’t mind those conditions. However, for the rest of us who want to try other plants, he offered some possible solutions to try. One I think is a distinct possibility. Under the drip line of the plant make 3 or 4 holes (depending on the size of the plant) and fill with a mixture of cocopeat or potting mix or peatmoss and ferrous sulphate (10 litre cocopeat to 1 cup ferrous sulphate) and cover with a layer of soil.

As an extension of this, I wonder if it would also work to remove the soil from the planting hole, place the plant, add the peat mix to the soil and back fill with it. It is worth experimenting.


One Response to “Lowering pH of Soils Information”

  1. […] However, in ‘Gardening Down Under’, Kevin suggests that potting mixes are designed to be used in pots to 125mm across and that clean soil should be used in tubs 225mm and larger. I have been thinking about this. I have a load of sandy loam and I think I will try a 50:50 mix of loam and potting mix in the large pots. This way I will still get reasonable drainage and water retention. It won’t stop the pots from heating up. I will need another strategy for that. The other problem is the weight of the pot. At least I will not be wanting to move them often. […]

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