September gardening and soil stewardship | Opinion and Commentary


Donna Palmer

Donna Palmer

The extended growing season of a mild Southern California winter means September is the month for earth, lettuce, sweet peas, and Santa Ana winds.

Here is a basic introduction to what lies beneath our feet in the garden. Soil is made up of four parts: mineral, air, water and organic matter.

An idealized sample consists of 45 percent mineral, 25 percent air, 25 percent water and 5 percent organic material.

These mineral particles in the soil create a texture that is identified as sand, silt, clay, or a combination of sand, silt, and clay. Loam is a crumbly balanced mix of all three.

As long as the garden soil is not completely replaced, as in container gardens and raised beds, the soil condition cannot be changed. It is the home of our garden. In Chino Hills it is usually clay.

Identifying soil texture helps us understand soil properties, primarily water infiltration rates and water holding capacity, which are critical to managing drought conditions and Santa Ana winds. Sand, the largest soil particle, feels gritty. Water penetrates quickly and easily, which means plants may need to be watered and fed more often as nutrients are easily washed out through sandy soils. Avoid drying out the soil in the drying wind.

Mud has smaller particles and can feel silky to the touch. It doesn’t clump too much when squeezed.

It can also hold water better. Water less than sand.

Clay (think Chino Hills) has the smallest particles, can be rolled into a ball when wet, cracks and becomes cement-like when dry, is notoriously difficult for water to infiltrate, but holds that water longer than silt or sand. Clay can hold nutrients longer and requires less frequent watering. If the water flow is low, water clay at a slow, constant rate to avoid runoff.

Most garden soils are made up of a combination of sand, silt, and clay, with one particle predominating.

In Chino we may find silty clay or even silty loam, a mixture of silty soil with significant amounts of clay and some sand. It can irrigate like silt, but store moisture like clay. Different experiments determine the soil texture: the floor tape test, the floor glass test, with a home test kit or sending a sample for a formal floor test.

Moist clay rolls into a ball in the palm of the hand; dry sand feels like the beach. An Internet search for “Soil-Jar-Test”, “Mason-Jar-Soil-Test” or “Soil Ribbon-Test” provides instructions for basic soil determination at home.

Aside from water efficiency, why is it important? The soil texture does not change, but the soil structure (the way these particles group together) can be improved. The addition of well-composted organic matter creates more reservoirs for water uptake and storage, more space for plant roots to expand, better drainage, attracts beneficial microorganisms and results in easier soil to work with.

September is a great time to replenish with abundant organic compost that will improve any type of soil and make fall plants happy. Apply purchased compost according to the instructions on the packaging or use it yourself. A better soil makes a better garden.

What to plant in a rejuvenated garden in September Sow early flowering sugar peas in the first week of September or day-long neutral sugar peas such as ‘Mammoth’ or ‘Velvet Elegance’ by the middle of the month for fragrant flowers at Christmas.

Weather permitting, greens, chard, and leafy lettuce can be sown in the garden towards the middle of the month / end of the month, but heat and wind can mean shade.

Maybe you opt for beets, radishes, or carrots. With so many options, you can plant vegetables that you love to eat!

Donna Palmer is a San Bernardino County gardener (Class 2021) who lives and gardens in Chino Hills. The University of California Cooperative Extension Master Gardeners in San Bernardino County has a toll-free line to answer your gardening and landscaping questions: Visit: for a list of upcoming courses and events