December brought the blessing of rain, and a few cold nights; just enough to let the plants know that it is winter. In our microclimate, the year is like the proverbial snake eating its tail. Fall’s colorful leaves still persist as the first spring blossoms make a tentative trial. In just a few short weeks, we’ll see our first plum blossoms, and then the year will unfurl again, as it has so many times before.
But this year brings change, and not just on Inauguration Day. During the end of the twentieth century, drought in California was news. Water rationing came, but mostly went. Gardeners let their lawns go brown, and carried water from the shower in buckets to their favorite roses and rhododendrons. Then, we mostly just waited for water rationing to go away again after a year or so.
Now, because of population growth, urban sprawl, and climate change, water rationing is beginning to look like a semi-permanent situation. Housing developers, agriculture, and wildlife protection all compete for the scarce drops of water, and home gardeners must stand in line with everyone else. Many of us will need to “retool” our gardens for a new reality.
One of the most important tools in our toolbox is called “hydrozoning.” Just as the garden is divided into sunny and shady areas, with appropriate plants in appropriate places, it can also be divided into irrigation zones, such as completely non-irrigated areas, areas with occasional deep summer watering, and areas with regular water. For this to work, plants with similar water needs must be grouped together, just as sun-loving plants are grouped together in a south facing border while ferns and fuchsias gather in the shade.
If part of the garden is designated a “no irrigation zone,” perhaps a sloping area, or the back or side of the garden, this area can be planted with California natives, or non-thirsty plants from other similar climates zones where a half-year drought is nothing unusual. This garden area will reward you with bursts of color in the winter and spring, as our annual rains stimulate the growth cycle of these plants. During the summer, they will stay neat while dormant and discourage weeds which would otherwise grow there.
It makes sense that native plants from the S.F. Bay Area or nearby parts of California, will thrive in our unamended soils and with the weather conditions provided by nature. But some of these plants can also give fabulous blooms and garden effects that make them classy performers anywhere. Some examples are California wild lilac (Ceanothus), flannel bush (Fremontodendron), California sagebrush (Artemesia californica), and matilija poppy (Romneya coulteri).
Equally good in unwatered plantings are tough customers from similar climate zones all around the world where they have evolved to thrive with mild wet winters and cool, dry summers. Some of the top performers are Leptospermums and grevilleas from Australia, and Leucadendrons and Phormiums from South Africa. Consider also plants from the Mediterranean such as rosemary, lavenders, and rock roses.
The next part of the garden can feature plants that benefit from an occasional deep watering during our annual drought, but that don’t mind going dry in between. Think about creating a transition zone between the completely unwatered background areas, and those that receive regular water and attention, which are probably closer to the house. Because these plants are sustained by occasional deep watering, they can extend your garden’s beauty into the summer and fall months. They can be useful as well as beautiful.
This would be the perfect water zone for a planting of culinary herbs such as sage, thyme, and oregano. Annual herbs like parsley and basil belong with the vegetables in the regular watering area. Many other fragrant and lovely plants will perform their best under these water conditions. They actually don’t want their soil constantly moist and will benefit from drying out between waterings. Some of these plants are the cornerstones of the perimeter border here at the Garden for the Environment, and some of them bloom without stopping all year around. They include Copper Canyon daisy (Tagetes lemonii), tree mallow (Lavatera maritima), and many dramatic sages, including Salvia mexicana.
The final section of the garden will receive regular watering; here are the vegetable and annual flower beds, and the fruit trees along with a few prized ornamentals such as the rose from grandma’s garden or the white azalea which reminds you of home. By concentrating irrigation water where it will do the most good, and grouping plants together that need a moist soil during the summer months, we can save water and money while still getting great results from our plantings.
For those of us with established gardens, this is a great time of year to look over the garden as a whole, and make some decisions that will save water next summer and for the future. The rainy season is the best time to transplant old favorites into new garden spots, or to plant out new purchases. Many ornamental trees, fruit trees, and roses are available bare-root now, and it is an excellent time for planting. Many natives and other drought tolerant plants are best planted in the fall as the rains first begin, but that chance is gone for this year, and now is the second-best time, with days beginning to get longer and many months of moist soils still ahead. Those of us who are just getting started with a garden, have the advantage of planning hydrozones from the beginning, and can put each plant in the watering zone it prefers.
Any plants transplanted to new locations in the garden, or newly planted out, will need irrigation in the summer months ahead, even if they will eventually be drought tolerant when established. The first few years in the ground, even drought tolerant plants need regular, deep watering, in order to get a strong deep root system established. If you reorganize your garden this winter to hydrozone, keep a close eye on transplanted and newly planted friends. Don’t let them wilt. Keep them growing this summer and next, and they will reward you with many years of beauty for years to come, without running up your water bill.