Sustainable gardening in Southern California means coping with highly variable precipitation. This month, we’re continuing to manage the effects of an epic four-year drought. And now scientists are cautiously predicting an El Niño winter, with higher than average amounts of rainfall. Yup, that’s gardening in our capricious mediterranean climate!
The U.S. Weather Service has official precipitation records for the L.A. Civic Center going back to the 1877-78 season (the water year runs from July 1-June 30) . Since then, the average yearly rainfall is 14.93 inches [1, 2]. During the 138 year period, extreme precipitation years (both high and low) have become more common.
The graph above shows the number of years below and above the average for two 25-year periods: 1890-1915 and 1990-2015. One thing is clear: there are more ‘extreme precipitation’ years (both below and above average) in the current period. The last 25 years had 10 years with a deficit of at least 5 inches. This compares to 6 such years in the earlier period. But there were also 6 years with 5 or more inches over the average (compared to two from 1890-1915). So we need to prepare not only for more ‘drought’ years, but also for more ‘wet’ ones.
We gave you some tips for surviving the drought (http://mother-natures-backyard.blogspot.com/2015/07/surviving-drought.html) and summer planning last month: http://mother-natures-backyard.blogspot.com/2015/07/summer-time-for-garden-planning.html. This month we suggest ways to prepare for this winter’s rains - El Niño or not.
First, a word of caution. Mother Nature’s Backyard is situated in the flat lowlands of the Los Angeles Basin. Our advice is most applicable to gardeners in similar areas. If you live in the foothills, and particularly if you live along a creek, in areas below recent burns, or those prone to landslides, you may need to take additional precautions. Consult your local municipality for advice on preparing for an El Niño winter. Recent ocean temperatures indicate that this may be a very wet winter. Prepare now if you live in a flood-prone area!
The rest of us still have several months to make our gardens both more water-wise and more El Niño proof. Some of the suggestions below may not be applicable. But we hope you’ll adapt some for use in your garden – and get moving on making them happen. The time is now to prepare for the winter rains.
1. Consider decreasing the area covered with impervious materials. Traditional walkways, driveways, concrete or mortared patios all are impervious surfaces. Water runs off them and, very often, into the storm drains and out to the ocean. That’s one reason why urban areas like the Los Angeles basin need such extensive storm drain systems.
El Niño years can be tricky. Whether they bring deluges or persistent showers, excess water can become a challenge for local gardens. Fortunately, you can take several steps to prevent/decrease the effects of running or standing water in your garden.
One strategy is to increase the percentage of the yard that can infiltrate rain water. This allows more water to infiltrate in place, rather than aggregate in ponds or rivulets. We discuss several infiltration options below (see suggestions 2 & 3). Another idea is to simply convert impermeable surfaces to permeable ones. This helps control excess rain water and also increases the amount of irrigation water available to plants (by decreasing summer run-off).
|Permeable walkways in Mother Nature's Backyard|
There are many ways to make walkways, patios and driveways more permeable (see the links below). Some, like replacing your driveway with permeable paving materials, require more time, skill and money. Others, like converting an old concrete patio or walkway into something more pervious, can be done quite economically, if you’re able to do most of the work yourself. For ideas on permeable surfaces see:
2. Use the rainwater that falls on your roof. Your roof is a large rain collector. Does the water from your roof end up in the storm drains? Does it make a muddy mess around your house, threatening the health of your foundation? If so, now is the time to install gutters and harvest rain from your roof.
|A rain chain is another way to direct water from a gutter|
The advantage of gutters is that they let you direct the water collected by your roof. You can then store the water (see #4, below) or direct it to places where it can be infiltrated into the ground (#3, below). For more information on rain gutters see: http://mother-natures-backyard.blogspot.com/2013/02/harvesting-rain-gutters-downspouts-and.html.
3. Infiltrate more water into the ground using a rain garden, dry well or dry swale. Water from impermeable surfaces must go somewhere. In the past, most of it has ended up in the ocean. But each year, more California gardeners are installing simple infiltration ‘devices’ in their gardens.
While getting rid of one problem (excess runoff), these devices also solve another: providing deep water resources for trees and shrubs. They allow water to infiltrate into the ground, replenishing the ground water. Trees, shrubs and other long-rooted plants can then access this ground water well into summer.
If you have an area where rain water puddles, you may want to consider a simple infiltration device like a dry well. These take little space, are relatively easy to install, and often solve the puddling issue admirably. They can be used in unplanted areas, making them a good option for patios and utility areas covered in gravel mulch. See the links below for more information.
|Rain garden - Mother Nature's Backyard garden|
Rain gardens and infiltration swales are the perfect complement to rain gutters, infiltrating the water from a roof. While no two rain gardens or dry swales are the same, they all slow or store water briefly, allowing it to percolate into the ground. They can be planted or not; they can be disguised as a natural-looking dry creek. Some are used as seating or play areas in the dry season. And they allow you to use plants that like a little extra winter water, even if the rest of your garden is quite water-wise.
Rain gardens, dry wells and dry (infiltration) swales are easy to incorporate when you are installing a new garden (or re-doing an old one). Like all hardscape features, they’re easiest to install before a garden is planted. If you’re removing your lawn, now is a good time to consider whether a dry well, rain garden or dry swale is right for your garden. Here are some good resources:
· Plants for Rain Gardens and Vegetated Swales: http://www.slideshare.net/cvadheim/rain-gardensswales
4. Consider storing some water. People in dry climates around the world store rainwater for use in dry periods. The regulations on rain water collection/storage are changing, so check your local municipality to learn what is legal. Nearly all S. California municipalities permit you to store water in rain barrels, to be used for watering your garden (not for drinking).
As rain water storage gains popularity, more options are available locally and on-line. Fifty gallon plastic rain barrels are sold at many hardware and do-it-yourself stores. Some water companies give them away for free or at low cost. And larger storage containers are also becoming more common. For more on rain water storage see: http://mother-natures-backyard.blogspot.com/2013/06/harvesting-rainwater-rain-barrels.html
As water becomes more scarce (and costly) it’s silly to not take full advantage of the rain that falls on your property. California law is now clear – you own that water! Don’t let it slip away. Act now to use your clean, free rain water this winter.
5. Use the ‘high’ and ‘low’ spots in the garden to best advantage. Sandy soils dry out quickly in summer; clay soils tend to hold water, creating wet spots in winter. Most gardens have areas that are ‘high and dry’ and others that are low and moist. If not, it’s relatively easy to create a bit of garden topography with low berms (artful mounds) and shallow swales.
Whether your soil drains quickly, slowly, or somewhere in between, creating modest garden topography has several advantages. First, a planted berm is often an excellent way screen short, unsightly views (for example to block views of parked vehicles). Berms and swales can also be used to direct and infiltrate rain water. And they add interest to a flat garden.
Another benefit of berms and swales is that they allow you to grow plants with water requirements slightly different from those available in the rest of your garden. For example, plants that hate wet feet can be grown at the top of a berm (driest place). Plants that like a little extra water often do well at the bottom of a slope or swale. For more on creating garden topography see: http://mother-natures-backyard.blogspot.com/2012/12/getting-to-know-your-gardens-soil.html.
|Fresh organic mulch: Garden of Dreams, CSU Dominguez Hills|
6. Consider replenishing mulch a little early this year. Newly laid mulch is more vulnerable to washing away. If you use mulch, consider doing your fall mulching in late summer or early fall. That will allow the mulch to compact a bit before the winter rains. For more on mulches see: http://mother-natures-backyard.blogspot.com/2012/07/understanding-mulches_23.html
7. Use the weather forecast to plan fall pruning. Fall pruning is best done after the fall heat waves but before the winter rains. Predicting the best time to prune can be a challenge. Consult the long term weather forecast when scheduling fall pruning. Don’t forget to consider the birds and other creatures that rely on your garden for food. For more on the topic of fall pruning see: http://mother-natures-backyard.blogspot.com/2014/11/maintaining-your-new-california-garden_15.html
|Fall pruning - Mother Nature's Backyard garden|
8. Choose trees, shrubs and vines that can take both drought and excess rain. Global climate change makes planning for the future a bit more challenging. We’re already seeing some effects: hotter temperatures overall; more temperature and precipitation extremes; changes in the timing of the seasons. The recent drought is just a taste of things to come.
Trees, vines and large shrubs are an excellent way to provide shade. In fact, all local gardeners should be planting now for future shade. With planning and proper care, large shade plants can live for many years. But choosing the best adapted plants is something we’re just beginning to grapple with.
In Southern California, our best choices will need to withstand both the periodic droughts and periods of greater precipitation. Only certain plants are so adapted. California native trees and shrubs are better candidates than those from the tropics or other regions with plenty of precipitation. But what native trees and shrubs will be able to take both the heat and the precipitation extremes? We have some ideas and will discuss that topic next month (September, 2015).
|Planting Mother Nature's Backyard garden|
9. Take advantage of winter rains for planting. Winter is the easiest time to plant in lowland Southern California. Soils are well-moistened and the temperatures cooler. That’s why California native gardens are traditionally planted in late fall or winter.
Winter is not only the easiest time to plant, but it’s also the best for plant health. California native plants are adapted to our seasonal weather patterns. Many are dormant (or at least slow growing) by late summer or fall; they are primed to grow with the winter/spring rains. Plant them in late fall/winter and they will establish themselves right on schedule.
But plant California native plants in summer and they’ll be ‘seasonally confused’; the heat says ‘it’s time to go dormant’ while the irrigation water says ‘it’s time to grow’. In fact, summer planting is difficult not only for the plants, but also for the gardener. Planting with the rains is yet another example of working with Mother Nature. Gardening elders have learned – often through painful experience - that working with Mother Nature is better than trying to work against her!
An El Niño year can be an excellent opportunity to start a new garden – or plant trees and large shrubs. So do your summer planning now. Figure out what plants you need. Plan to buy required plants at the fall plant sales, and plant them with the winter rains.
|Rainy day - Mother Nature's Backyard garden|
10. Enjoy today’s weather, whatever it may be. The news on climate change can be downright depressing. The best antidote is to sit in your garden. Enjoy the hot, dry days of late summer. Watch the abundant life that enlivens California gardens this time of year. Enjoy the balmy evenings – and vow to plant more silvery-colored shrubs to enhance your twilight garden.
Look forward to the cool rains. Sit out in your covered patio and smell the rain. Listen to the sounds of a rainy day in your garden. Watch the birds and other creatures – what are they doing on a rainy day? Put your potted plants out to benefit from the good, pure water.
Those of us in California are blessed with a wonderful climate, with seasons that promise beauty and interest every month of the year (http://mother-natures-backyard.blogspot.com/2014/09/seasons-in-southern-california-garden.html). But where ever you may garden, there’s something wonderful in your garden right now. So, enjoy today’s weather – whatever it may be.
We welcome your comments (below). You can also send your gardening questions to: firstname.lastname@example.org