How to deal with our Marin clay soil.

One of our most common questions is, ''How can I deal with this Marin rocky clay-based soil?'' The answers lie in how much time and effort you want to expend. Changing soil texture is generally considered hard to achieve. Understand there are benefits to a clay-based soil such as water and nutrient retention. But we want a garden with that soft earthy smell to its soil. So here are a few strategies to try.

You move or remove it.

If you are really into gardening and and just hate your soil, well, moving might be the answer. It sounds radical and expensive, but it may be the right answer over the long term. Most of us have all kinds of inspections done on our prospective new home but few have the soil tested. Food for thought on your next move.

Another expensive solution is to have the soil excavated and replaced with a more amenable soil. This is probably the fastest answer but maybe one of the more expensive ones as well. It also has some unintended consequences with creating unincorporated layers that can have drainage issues.

It may seem like a good idea to simply dig a bigger hole for the desired plant and replace the clay soil with topsoil. The results might be fine in the short term but think about what you have done to the plant. You just placed it in a larger pot that has little to no drainage. Given our heavy winter rains, root rot is a strong possibility.

Live with it.

Perhaps the simplest answer is to live with it. You can plant native species that have specifically evolved to deal with our soils and climate. The common complaint is that native landscapes are boring and unattractive in the summer when we want to enjoy our gardens the most. There has been a great movement to improve the native designs of landscapes to provide year-round enjoyment. While many of us still want our roses and lawns, going to a native design in some portions of our gardens can deal with soil issues as well as the other many benefits that a native garden provides.

Another common solution to dealing with our clay soil is avoid it by building raised gardens. Raised beds can be simple and are a very fast and effective way of dealing with clay. It is amazing the amount of vegetables, fruits, and flowers that can be grown year round in a raised garden bed. It will also save you water and backaches. There are many designs on the internet that can fit your specific needs.

Amend it.

There are many sources that advocate various methods of amending clay.

Adding sand or gypsum are two of the most common. Our research on these solutions have lead us to avoid them if possible.. There are plenty of testimonies as to their effectiveness but there equally numbers of disaster stories. If you choose this path, do your research (get your soil tested) and move in small increments. More is not always better.

Adding organic matter.

Mulch

Using mulch helps protect your soil from erosion and solarization. It lessens water evaporation by insulating the soil from the sun and the wind. Organic mulch will eventually breakdown into compost and feed your soil. Sheet mulching is a very effective way of breaking down clay and controlling weeds.

Use Compost

Compost is full of biology and food for the plants microbes in your soil. The microbes in your soil breakdown the organic material and exude them in a plant soluble form. These microbes help aerate and aggregate the clay particles. Improving your soil structure will, among many things, promote root growth and potentially save you water.

Use Compost Tea

Using mulch and good compost will over time restore most or all the biology to your soil but that takes time. Nature's clock isn't the same as ours. Actively Aerated Compost Tea (liquid compost) helps accelerate this process. This liquid compost is a water extract that is full of beneficial microbes (bacteria, fungi, protozoa, nematodes, etc) that is applied to your garden. These soil organisms store nutrients, fix nitrogen, breakdown organic matter, and decompose toxins. They improve soil structure, water retention, and promote root growth.

Plant Cover Crops.

Cover crops, also called green manure, are a great way to improve soil aeration, add nitrogen, and support and encourage microorganisms and worms. Cover crops shield the soil from sunlight, wind, and heavy rainfall thus improving soil structure, water infiltration, and root penetration. Additional benefits include reduced soil crusting, soil erosion, runoff, and nutrient leaching. Cover crops enhance soil fertility via improved nutrient retention and cycling while leguminous cover crops add nitrogen from the atmosphere. A cover crop is termed a green manure crop if the residue is incorporated in the soil; in such instances, crops should be selected that produce large quantities of herbage and also contain adequate amounts of nutrients in the correct proportions.

What do we do?

We use a combination of some of the above. We go 'native' in areas that are not focal point of our landscapes thus saving water as well. We use raised-beds for the edibles. We use mulch and compost (lots of it) throughout our garden, less so with the natives. And we apply Aerated Compost Tea everywhere.