Plants have always been my passion, but inÂ our hot inland valleyÂ during the long hot summer monthsÂ and no rain in sight until late November or December,Â and with fast drainingÂ DG soil Â (decomposed granite), proper watering becomes important, and determining the right irrigation amount, frequency and duration is an on-going task.
In the past years our reservoirs have emptied to very low levels and water prices have shot up.Â First I learned to recognize drought stress, and then it became obviousÂ that my planting design needed to become more sustainable:Â I had too many plants with greater water needs than I felt was warranted, andÂ the remaining ones were too close together, requiring more water and more maintenance to remain tidy.Â Out came manyÂ popularÂ plants, such as as Garden Penstemon,Â KangarooÂ Paw and Lambâ€™s Ears, and most of my roses were sacrificed as well (Iâ€™m down to one that can do withÂ less water -Â the climber Mermaid).Â
Although it may sound like a painfulÂ sacrifice, it was not:Â On the way to that easier-to-maintain and less thirsty garden I am discovering many beautiful plants that are doing very well here, like Flannelbush or Mountain Lilac from California, Proteas from South Africa,Â Â Texax Ranger from the Southwest and Northern Mexico,Â succulents from South Africa or California itselfÂ … the list is long and exciting, and I will be writing in more detail about some of these exceptional plants in future posts.
Lots of mulch:Â Â I try to keep the layer at least 3 inches thick,Â on top of the soil around trees and shrubs and in between my perennials; even in my vegetable garden I try to apply it where possible.Â Â IÂ prefer a medium textured bark or similar mulchÂ with pieces of about one-inch in size; this will allow water to pass quickly through the mulch into the soil instead of being retained by the mulch.Â Â My irrigation systemÂ applies water infrequently andÂ deeply; thisÂ keeps the mulch dry and optimizes its water-saving potential.Â Every yearÂ I replenish a good inch of this layer as it decomposes slowly, enriching my soil.
Mulch is probably being put to good use in your garden, too:Â The multiple benefits of this material can hardlyÂ be gained otherwise.Â Â Â But you might haveÂ some areas where mulch is difficult to apply, as in a vegetable garden.Â Here shallow cultivation between watering cycles, with a hoe to 2-3â€ deep, loosens the soil, destroys weeds, aerates the roots and assists in reducing water needs. (Be careful not to injure delicate surface roots around tomatoes and corn.)
My most practical, diagnostic gardeningÂ tool is a soil moisture probe:Â This is a stainless steel tube, about 24 inches long,Â fitted to a comfortable T-handle. Â When pushed into the soil and pulled out again, a partialÂ cut-outÂ in the long end of the Â tube lets me check the plug of soil in the tube:Â I can seeÂ how deeply my watering has penetrated, or how much remaining moisture is in the soil if I am unsure whether itâ€™s time to water again. Â It also allows me to see how deep the roots have grown and, subsequently, how far down my watering should penetrate.Â If I suspect a disease, such as a fungus rot, the roots in the soil plug tell me how healthy they are by their looks and feel:Â If they are grayish, soft and mushy, they are â€˜sickâ€™ and unable to perform their job.Â The smell test is important, too:Â a healthy soil has a good earthy smell, so if thatâ€™s off I know that a soil-borne disease is troubling my plant, or that the roots have died because of too much water.
In my landscape design work and horticultural consultations, too, this probe is invaluable:Â Â Together with a drainage test it helps meÂ determine my client’s soil type and guides my selection of the plants that will grow in this soil (usually we send a soil sample to a spealized laboratory to be analyzed for its texture and nutrient content).Â This tube is well worth its cost of aroundÂ $65 (check withÂ the irrigation and landscape supplierÂ Hydro-Scape, 5805 Kearny Villa Rd,Â San Diego at http://www.hydroscape.com/ )
Christiane Holmquist Landscape Design.Â Â Â Â [P] 760-586-6065