Thinking about lawns and gardens during this powerful summer heat

Joshua Siskin writes about gardening in Southern California each week.

With the recurring droughts we have endured over the past several decades, lawns have all but vanished from Southern California. 

Perhaps I should say new lawns since some old lawns are still green and do not need copious amounts of water to stay that way. Often these are hybrid lawns that may have started as tall fescue (typically the Marathon brand) but over time were taken over by perennial grasses such as Bermuda and Kikuyu grass. The former has thin blades and the latter has wider blades resembling those on St. Augustine grass. Both have underground rhizomes and surface stolons (runners) that allow them to survive drought, with Kikuyu stolons thicker than those of Bermuda grass. One of the most popular uses of Kikuyu is on golf course fairways due to its toughness. 

If you live near a park and see grass growing, it will more than likely include Kikuyu grass and its ropey stolons. The stolons will root wherever a node — the point on the stolon from which a leaf grows — touches the ground. If you collect the clippings cut from a Kikuyu lawn, you will have pieces of stolons from which you can start a drought-tolerant lawn, so ask whoever is mowing a Kikuyu lawn to give you their clippings. Take the clippings back to your yard and plant them horizontally, taking care that the stolon stem pieces are buried under the soil surface while the leaves are exposed. Water well until the clippings begin to root; after rooting starts, irrigation frequency can taper off. Once a Kikuyu lawn is established, it should never need more than two weekly irrigations to look good and it can survive on much less. You can also grow a Kikuyu lawn from seed, which is available through Stover Seed (stoverseed.com) 

The downside of Kikuyu is that in the manner of all tropical or warm-season grasses: It goes dormant in the cold, although during mild winters it may stay green. However, dormancy is an opportunity to do vertical mowing which serves to break up the layer of thatch formed by Kikuyu. This is a process that will make it easier to walk on your Kikuyu lawn when it regrows because the thick spongy thatch will have been removed.

The Kikuyu are the largest ethnic group in Kenya and it was from this people’s ancestral lands that, in 1911, Kikuyu seeds and stolons were taken for eventual distribution throughout tropical and sub-tropical areas of the globe. It first arrived in the United States in 1918 in Pacific Palisades where it was used to control erosion on drainage ditches. From there, it spread by windblown seeds throughout Southern California. In flowerbeds, it is a nasty weed due to its deep rhizomes and aggressive stolons. Still, its toughness makes it the best lawn grass option by far when our ever-present threat of drought is taken into account. 

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As lawn substitutes, gardeners often turn to ground covers, especially those which seldom if ever need watering once established. The uniqueness of such ground covers, first and foremost, is the blanket-like growth of their foliage. Their small, tightly arrayed leaves make it impossible for water to escape from the soil. At the top of the list of these ground covers is rosea ice plant (Drosanthemum floribundum). It forms a thick mat of one-inch succulent leaves. In late winter and early spring, its flowers — pink or lilac-purple depending on the variety — are so dense that foliage is invisible. When leaves are visible, they are covered with what look like ice crystals, an effect of the sun striking minute cuticular protuberances known as papillae. 

Trailing rosemary (Rosmarinus officinalis prostratus) is another ground cover whose maintenance is virtually waterless. Its tiny leaves seal off the ground to such an extent that water loss from the soil surface is impossible. It should be noted here that all rosemary species are extremely resistant to drought and never need more than one or two good soakings per month, no matter how hot is gets. Lantana is another ground cover in this category. Here I would recommend the shrubbier types — in yellow, orange, orange-red, or confetti (yellow, orange, and pink) — which can be kept as low as six inches tall through regular pruning. While there are popular trailing, more classic ground cover lantana cultivars in lavender-pink and white, their longevity does not approach that of their taller cousins.

Two ground covers that are not often seen are excellent for partial sun to shady exposures where their tight-knit foliage obviates the need to water them. One of these is Asian jasmine (Trachelosperumum asiaticum) and the other is dwarf periwinkle (Vinca minor). Both have lush, dark green, diamond-shaped leaves that are an inch long and provide an elegance unmatched by other ground covers.

I was inspired to write about ground covers after receiving an email from Matthew Hunt, who gardens in San Clemente and has been growing ground morning glory (Convolvulus sabatius/mauritanicus var. Compacta) for eight years in “mostly sun to partial shade.” I have marveled at the flower power of this ground cover for years as its lavender-blue gramophone-shaped blooms are prolifically displayed throughout the summer and into the fall.

California native of the week: Small-flowered morning glory (Convolvulus simulans) has tiny five-petaled flowers in pink or blue. It is an annual that — in the manner of many morning glory species — vines it way up neighboring plants to create more sun exposure for itself. It is found throughout Southern California and is often located in clay soil, an unusual circumstance for California natives, the vast number of which thrive only where soil drains well. Its genus name is derived from the Latin convolvere which means “to twine around.”

Please send questions and comments to joshua@perfectplants.com.