Soil Improvement

Gardening Question From Kate:

Hi Pat, I attended the orange county master nursury class you gave about soil last month. When I went to buy some amendment the man at the garden store, ( South Coast Gardening Supply),told me to use gypsum and gro-power 5-3-1. He suggested I turn over the soil well and put those two ingrediants into soil by handfuls. I had never heard that suggestion before My soil is not bad but it definitely is tired. What do you think?

compost photo

Photo by normanack

Answer from Pat:

By “tired soil”, you perhaps mean depleted of nutrients and organic materials. As I explained in my lecture, if your soil is clay and if it is compacted due to alkalinity, not due to mechanical compaction, then gypsum will help break it up and make it drain. As I also explained, if your soil is not clay soil then adding gypsum will do absolutely nothing at all to improve the soil.

As I explained in my lecture as well as adding gypsum to clay soil, the best way to improve all soil is to dig in a 4-inch thick layer of well-composted organic materials and then to cover the ground with mulch every year or perhaps even twice a year. In Orange County you can have compost and also mulch trucked to your driveway by such companies as this one which I found just now on the Internet. . I am not recommending this company but only showing you that you can find these sorts of products by hunting several ways, including the internet. Another way is to look in the yellow pages. Purchasing compost in bags is much more expensive.

As I explained in my lecture, you also need fertilizer, which should be applied to plants when they need it. The normal time to fertilize the basic landscape is in March. Fertilizing tropicals, for example, now is not a good idea since it will stimulate growth when these plants need to slow down and prepare for winter. Grow-Power, which was recommended by your nurseryman is an excellent fertilizer. It works well, but it is not fully organic. If you are concerned and confused about what to do why not purchase a copy of my book and begin using it month by month each month you are in so you will know what to do when and gradually get the hang of things.

Another fairly inexpensive method of improving your soil’s organic content and fertility is to cover all bare ground now in fall with a thick layer of manure and then dig it in in spring. It you have sandy soil this is particularly effective and right now in fall is a good time to do it. You can find good horse manure from stables or individual horse owners. The odor goes away in a couple of days, especially if you are irrigating. When using chicken manure less is needed. Aged chicken manure can be purchased bagged and you can dig it straight into the ground for example in the vegetable garden. As a general rule don’t dig fertilizers into the ground around plants since you will damage roots. Simply apply fertilizer at the right times of year for each plant and then water it in.

Photo by Sustainable sanitation


  1. I live in s. new mexico. there is hardpan (caliche) soil. I read that soluble gypsum will help. I can’t find any. will gypsum pellets work?

    • Thank you so much for your excellent question. The answer is that gypsum can help but only as one step in a multi-step effort.

      Caliche is a highly alkaline type of soil found largely in desert areas. Its high lime content may be visible as white flecks or as a white crust on top of the soil, or it may occur in a hard buried layer. Here are the solutions:
      Try to break through to a layer that drains.
      Apply gypsum to wash away salts.
      Plant salt-resistant plants.
      Apply humic acid (and leonardite if available.)
      Apply compost and other acid amendments.
      Plant in raised beds.

      Good luck with this project.

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