Soil Probe and Mulch - Two essential tools to help you conserve water and keep your landscape healthy

I am fortunate that I can experiment to some extent  in my own garden with  layouts and plants touted  "drought tolerant" and "water wise", and that I can practice the techniques of planting, maintenance and water conservation that I explain to my clients.

Plants have always been my passion, but in our hot inland valley during the long hot summer months and no rain in sight until late November or December, and with fast draining DG soil  (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. First I learned to recognize drought stress, and then it became obvious that my planting design needed to become more sustainable:  I had too many plants with greater water needs than I felt was warranted, and the remaining ones were too close together, requiring more water and more maintenance to remain tidy.  Out came many popular plants, such as as Garden Penstemon, Kangaroo Paw and Lamb’s Ears, and most of my roses were sacrificed as well (I’m down to one that can do with less water - the climber Mermaid). Although it may sound like a painful sacrifice, it was not:  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,  Texax Ranger from the Southwest and Northern Mexico, succulents from South Africa or California itself ... the list is long and exciting, and I will be writing in more detail about some of these exceptional plants in future posts.

Here are some tips and techniques to keep the ornamentals and the vegetables in your garden healthy and good looking through these hot months:Lots of mulch:   I try to keep the layer at least 3 inches thick,  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.  I prefer a medium textured bark or similar mulch 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.   My irrigation system applies water infrequently and deeply; this keeps the mulch dry and optimizes its water-saving potential.  Every year 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:  The multiple benefits of this material can hardly be gained otherwise.   But you might have some areas where mulch is difficult to apply, as in a vegetable garden.  Here shallow cultivation between watering cycles, with a hoe to 2-3” 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 gardening  tool is a soil moisture probe:  This is a stainless steel tube, about 24 inches long, fitted to a comfortable T-handle.  When pushed into the soil and pulled out again, a partial cut-out  in the long end of the  tube lets me check the plug of soil in the tube:  I can see how deeply my watering has penetrated, or how much remaining moisture is in the soil if I am unsure whether it’s time to water again.  It also allows me to see how deep the roots have grown and, subsequently, how far down my watering should penetrate.  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:  If they are grayish, soft and mushy, they are ‘sick’ and unable to perform their job.  The smell test is important, too:  a healthy soil has a good earthy smell, so if that’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:  Together with a drainage test it helps me 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).  This tube is well worth its cost of around $65 (check with the irrigation and landscape supplier Hydro-Scape, 5805 Kearny Villa Rd,  San Diego at http://www.hydroscape.com/ )Christiane Holmquist Landscape Design.     [P] 760-586-6065