Cooling the soil in summer heat Mulches that fertilize and conserve moisture |

Cooling the soil in summer heat Mulches that fertilize and conserve moisture

By Carolyn Singer

Special to The Union

Last week I shared some of my decomposed straw with a neighbor, a true gesture of friendship. His young vegetable starts were baking in the sun and reflected heat of the dark soil in his raised beds, and I slept better that night knowing he had protected his soil with this good mulch.

Each fall I purchase twelve new bales of straw. I prefer wheat or oat straw because it decomposes quickly, while rice straw will protect the soil but does not break down easily (though it usually free of seeds!). With my method of allowing the decomposition to begin while the material is still in bales, seeds sprout long before the straw is spread as mulch.

Wet the new bales and do not pull them apart. These bales benefit from sitting out in the winter rains, unlike a compost pile, which may get too soggy with rain and cold, delaying decomposition. This past week I have been amazed to find moisture in the middle of the bales. After all, when did they last get a good soaking rain? In March?

Of course, if you are just now bringing straw to your garden it’s better for your veggies to use it for mulch NOW! And expect some grasses to sprout. Pull them and tuck them under the straw. More food for the worms!

Compost may also be used as a mulch, and as you irrigate, the nutrients in the compost will be moved into the soil. The richer the compost, the more fertilizer value you add to the soil with irrigation. But even on top of a layer of compost, an additional layer of decomposed straw is ideal.

By July most of my vegetable garden is mulched. Vegetables are thriving with a three to six-inch layer or combination of layers covering the entire bed. Few weeds are able to grow, and moisture is conserved between irrigations, greatly reducing the amount of water required. Only very young seedlings from the most recent sowing of lettuce, beets, and carrots are lightly mulched.

Perennials, ornamental shrubs, and trees were mulched last fall with compost and leaves. The rock garden is primarily mulched with gravel, which also conserves moisture and allows plants that prefer a dry base to creep and root. While it has no fertilizer value, the gravel does protect the soil, allowing it to remain vital. California poppies thrive in this environment.

With the best of amendments in the soil, and a mulch to protect and enhance the soil surface, I may still consider supplemental fertilization. Fish emulsion and kelp are my first choices. Compost tea is another effective fertilizer to stimulate growth.

The odor of fish emulsion disappears quickly, and this is my preferred choice for containers of annuals. All my annuals are in hanging baskets or within the fenced vegetable garden to keep them out of reach of the deer. I have fed the Nasturtiums and Impatiens in hanging baskets only once this season because they are doing so well in the soil mix I created.

Kelp is a potent fertilizer. Be careful not to overdo it. I intend to do just two to three applications in my vegetable garden. The last application will be in early September. One last boost of a fertilizer that stimulates strong plant growth and builds resistance to frost.

Expect an abundant harvest of flowers, fruits and vegetable when your soil is fertile. All the effort is worth it!

Carolyn Singer has gardened in the foothills since 1977. She is the author of two books of deer-resistant plants: “Deer in My Garden, Vol. 1: Perennials & Subshrubs” and ” Vol. 2: Groundcovers & Edgers.” Gardening questions may be sent to

Support Local Journalism

Support Local Journalism

Readers around Grass Valley and Nevada County make The Union’s work possible. Your financial contribution supports our efforts to deliver quality, locally relevant journalism.

Now more than ever, your support is critical to help us keep our community informed about the evolving coronavirus pandemic and the impact it is having locally. Every contribution, however large or small, will make a difference.

Your donation will help us continue to cover COVID-19 and our other vital local news.


Start a dialogue, stay on topic and be civil.
If you don't follow the rules, your comment may be deleted.

User Legend: iconModerator iconTrusted User