Last month we envisioned your new garden: its
overall look and the features you want to include. This month we take the background information
and begin to actually design the
garden, starting with the water management system. So take out your Garden Notebook, grab a cup
of your favorite beverage and let’s get to work.
Introduction
Local gardeners need to seriously reconsider their garden
water management. Climate change will
almost certainly mean less water for gardens.
Californians should view the past two drought years as a wake-up call;
it’s time to make your garden more water efficient.
The traditional approach to water management was to
install a sprinkler system that watered the entire yard. With increasingly sophisticated technology,
many of us divided our gardens into irrigation zones/’stations’ that could be
watered separately. This helped conserve
water in many California gardens because it allowed for flexible irrigation
schedules.
The New California Garden approach takes
water management to a whole new level.
It starts with defining water goals for your garden. It asks you to carefully consider how you
‘spend’ your water budget, prioritizing water for the plants most important to
your family. And it involves working with the natural conditions in your yard; working
‘with Mother Nature’ rather than against her. While this may sound difficult, in fact it’s
fairly easy. You will need to do the
planning work and adopt a new paradigm for water management. But once
your garden management system is in place, water management becomes easy.
Determining your Water Goals
Start by reviewing your Water Goals. If you haven’t defined them, now is a good
time to visit our November, 2013 posting on Assessing Your Family’s Needs (Functional Analysis). You’ll need to work through the Water Goals
exercises before you can design your water management system. You must understand your starting point – and
where you want to end up. And only you
can set your water goals and priorities.
Let’s look again at our example garden at 112
Willow Street. 112 Willow represents a fairly typical S. California
yard. It has lots of good features,
which we explored and mapped in August, 2013.
We’ve conducted a functional analysis of the garden (September, 2013)
and mapped functional areas (November, 2013).
Part of the latest mapping exercise involved looking closely at the
physical attributes of the site. You
might want to re-read the November posting to prepare for today’s session.
As seen below, we want to decrease overall
water usage at 112 Willow Street. There
are areas in the new garden (the vegetable garden; possibly the new ‘lawn area’)
that will need regular water. These areas are important to the gardeners so they’ve
chosen to ‘spend’ water on them. But we’ll
have to balance them with areas that need less water.
The front yard is landscaped in a
low groundcover. It’s not very exciting
and doesn’t attract many birds or butterflies.
But it is evergreen,
established and fairly water-wise (it’s only watered once every 10 days, even
in summer). We’ve decided to retain the current
front yard landscape, at least for the next few years, and then re-evaluate.
It’s perfectly fine to re-landscape
your garden in segments – and to preserve existing plants that are functional,
attractive or important to your family.
However we suggest that you consider
the entire yard when designing your Water Management Plan and your hardscape
(March 2014). Irrigation systems,
walkways, rain harvesting systems etc. work better if the entire yard is planned
as a whole, even though individual parts may be installed over time. For example, modifications to the backyard
irrigation system may require modifications in the front yard. And traffic flow needs to be considered for
the whole outdoor area.
In the Water Goals analysis
we’ve identified areas at 112 Willow that tend to stay moist and others that dry
out quickly. We’ve also discovered a few
areas that are ‘difficult to irrigate’ due either to physical characteristics
of the site (for example, on a slope) or characteristics of the current
irrigation system. Now comes the creative part: we’re going to take what we
know about the site and use that knowledge to design an integrated water
management system for the garden. The
first step is to create a Water Zone Plan, the underlying foundation of a
water-efficient garden.
Creating a Water Zone
(Aqua Zone) Plan
Water
Zone gardening is based on grouping plants according to their water needs. It involves partitioning your garden into
Water Zones and choosing plants for each Zone based on their drought tolerance.
The Water Zones can range from no/infrequent summer water (Water Zone 1) to
regular irrigation (Water Zone 3). Water
Zone gardening is not difficult, but it does require some thought and planning. If you’re unfamiliar with the Water Zone
concept we suggest our posting on the subject (April 2012): http://mother-natures-backyard.blogspot.com/2012/04/water-wise-gardening-tip-save-water.html
The
first step in creating a Water-Zone Plan is mapping the
existing irrigation conditions. We’ve
created such a map for 112 Willow Street (below). You can see that most of the backyard
receives regular water (Water Zone 3).
It’s all on one sprinkler system – and the watering schedule is based on
keeping the sod lawn green. Much of the
current water budget is spent on the backyard.
The side yards only receive monthly hose waterings – just enough to keep
the existing plants alive.
If
we look closely at the existing Water-Zone map, it’s clear that the backyard
will need to be re-Zoned if we want to decrease water use. Currently,
about 75% of the garden is watered at least three times a month; 45% is watered
regularly. Change is obviously needed;
but how to proceed?
The
key to Water Zone gardening is the placement of water zones. This can be tricky
because optimal placement depends on site
physical characteristics as well as the uses
planned for each area of the garden. The 112 Willow site includes some physical features
that directly impact a water management system.
As seen above, some areas are naturally moist while others dry out more
quickly. Some areas receive more
sunlight and wind than others. In fact,
we already considered many of these factors when designing our final functional
area map (November, 2013).
One of the easiest ways to approach Water Zone
planning is to first map the obvious
areas: areas that will need regular water and those that could require none. We’ve mapped the ‘obvious’ areas for 112
Willow St. above. Mapping these areas can result in sudden flashes of
insight. The vegetable garden will require regular
water, so we’ve mapped it as Water Zone 3. On the other extreme, the
maintenance area could be ‘paved’ with a permeable hardscape like gravel,
crushed rock or pavers (Water Zone 1). This
would be a great solution, providing a solid work surface that requires no
water at all.
While considering the ‘maintenance’ area, we
realize that we could extend this Water Zone 1 area by removing the existing
groundcover around the driveway. The
groundcover is difficult to water in that area – and doesn’t look that great. We’ll have to consider our choice of
hardscape carefully (next month). But
converting the driveway area to permeable hardscape could significantly decrease
water use in the front yard and require just a little extra effort and cost. The driveway area is not a high priority area
in terms of usage, so converting it to Zone 1 probably makes sense.
We also decide that the eastern side yard could
easily be managed with little water.
We’ll have to choose our plants carefully and perhaps limit the number
of plants. But a few well-chosen plants
– with some inspirational hardscape – can turn this area into a shady spot for
reading, meditation and other quiet pursuits.
The afternoon shade makes this area a good candidate for Zone 1 or 1-2
(watered deeply several times a summer).
According to our Water Goals (above) we’d like to consider a water-wise grass for
the new, smaller lawn area. Our site assessment shows that the lawn will be
well-watered most winters; we’ve located
it in a low spot that tends to stay moist. But it will need some summer water.
Let’s assume it will need irrigation 3 times a month in summer; we can
revise this based the actual grass we choose.
We map the ‘lawn area’ (Zone 2-3, below) then consider what to do with
the ‘shady seating area’ under the apple tree.
We know from our site physical assessment that very
little grows in the shade under the apple tree.
We could use hardscape to create our seating area; we’ve seen nice
examples surfaced in gravel or crushed rock. But we decide to plant at least part with a
water-wise native ground cover (Water Zone 2).
This will work well for our apple tree, which is established and
requires only occasional water. The
area will likely also receive some water when the ‘lawn area’ is irrigated.
The new ‘butterfly garden’ presents some water management
challenges. The area slopes down to the
new lawn. It’s difficult to water and
the top of the slope (south side) dries out in warm weather; it would be helpful
to water this area less frequently. But
the area also provides views from the house and patio, so it needs to look nice,
particularly in spring/summer. We’ll
need to satisfy both requirements with our Water Zone plan.
We’ve located the butterfly garden wisely, in this
sunny part of the garden. We’ll want to
use plants native to S. California to attract the local butterflies. Fortunately, many native ‘butterfly plants’
are quite drought tolerant once established.
If we choose carefully, we’ll be able to water this area once a month or
so in summer. We decide that the
butterfly garden can easily be assigned to Water Zone 2.
Looking at the final Water Zone Plan, we’re impressed
by the difference between it and the existing conditions. Approximately half of the new garden
(including front yard) will require water once a month or less – a full 1/3
will need no water at all! Only the
vegetable garden will need regular water.
Since growing vegetables is an important activity, the gardeners are
happy to spend more of their water budget on the vegetable garden - and much
less on areas that are less important. We’ve got a workable plan!
In summary, the steps in creating a Water Zone Plan for your new garden
are:
- Determine your overall
water goal – often to decrease water usage; you may want
to specify the amount of decrease you desire.
- Map
out your current water use distribution – to
determine where your water budget currently is spent. Roughly calculate the percentage that
requires regular water (you may be surprised!).
- Study
the maps created for your site physical assessment. They may suggest areas that are already
more moist or dry based on soil conditions, topography, light and wind
patterns or other factors. You will use this information to guide the
placement of Water Zones.
- Review
your final Bubble Map. Are the use areas compatible with the
physical conditions? If not,
modify the map.
- Take a copy of your
final Bubble Plan (map of activity/use areas).
- Map
areas that will require regular water (examples:
vegetable garden; roses; some fruit trees; tropical plants; wetland/pondside
plants; conventional sod lawn);
- Map
areas that could require no water at all (examples: unplanted
areas like seating areas; areas just covered with mulch, including gravel
or other inorganic mulch; areas planted with some highly drought-tolerant
California native plants, particularly those native to Southern
California; areas utilizing desert plants).
- Roughly calculate the area that will require
regular water. Compare it to the percentage in your
current garden. You may find that
you’ve already reached your goal for decreased water use. If not, these calculations will indicate
how much of the rest of the garden will need to be Zone 1 or Zone 2.
- Assign
Water Zones to the remaining areas of the garden. This must be based on a realistic
assessment of the physical characteristics of the site as well as the
functional needs of each area. Be
creative: you may be able to use attractive hardscape (pavers; stones;
statuary) and judicious use of plants to create an attractive oasis that
requires very little water. We’ll
consider hardscape matters next month.
- Create
your final Water Zone Map, realizing that you may need to modify the
map when you choose your hardscape and plants.
Managing
Rainwater/Harvesting Rain
Garden water management should include strategies
for managing rain. Rainwater is clean, free water. Inhabitants of other dry and Mediterranean
climates (for example S. Africa, Australia and even parts of the U.S.
Southwest) have long made use of every drop of rainwater. We can learn a lot from them. Among the techniques they use are: saving
rainwater for later use; diverting roof runoff for use in the garden; creating
holding basins to allow water to percolate into the ground; using pervious pavement/hardscape
and more.
You may want to include one or more of these
strategies in your New California Garden. We’ve discussed several of them in previous
postings.
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Topic
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Link
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Introduction to harvesting rain
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Gutters, downspouts & rain chains
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Rain gardens & vegetated swales
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Dry swales/dry ‘creek beds’
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Rain barrels, cisterns & storage
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Permeable paths, patios, etc.
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Hopefully you’re now inspired to include some rain management
methods in your own New California
Garden. After reading about harvesting
rain, the gardeners at 112 Willow Street added several new ideas for using
rainwater to their Water Goals.
As noted on the map below, the house already has
gutters front and back. There’s
currently no gutter on the patio – a source of irritation and drenchings during
the rainy season. We decide to add a
gutter and downspout that will direct water from the patio roof to deep water
the apple tree.
The back gutter drains to the west. In fact, the area near the kitchen door is
often muddy after a rainstorm because of the downspout location. Fortunately, the downspout is close to the
proposed vegetable garden; the gardeners would like to use this water to irrigate
the vegetable garden in winter/spring. Is this feasible? First
we’ll need to calculate how much water we’d actually harvest from the back roof
during a typical storm.
We discuss how to do the calculations in our
posting on rain gardens and vegetated swales (above). Calculating the amount of runoff is fairly
straightforward. Let’s assume that a good winter storm delivers
¾ inch of rain. We do the calculations and
are surprised that the back drainage will deliver 38 cubic feet (or 284
gallons) of water during a good winter storm.
The front drainage will produce even more: 57 cubic feet or about 426
gallons. That’s a lot of water!
The gardeners at 112 Willow Street have several
options for their back roof drainage. If
they’re concerned about the volume of water, they can split the drainage so
part drains to the east and part to the west.
That option requires some work on the existing gutter and installing a
new downspout on the east side. But it
will insure that rainstorms don’t overwhelm the vegetable garden and will also
supply water to the ‘meditation garden’.
Alternatively, the gardeners may decide to incorporate
rainwater storage into the vegetable garden.
For example, three 50-gallon rain barrels, connected together in series,
could store half of the water from a typical storm. The overflow could be used to deep water the
vegetable garden. A larger storage
container (often 300-600 gallon capacity) could store all of the runoff from a
typical storm. The water could then be
used during dry periods in winter and spring.
We’ll have to design a creative solution for getting
the water from the downspout to the garden area. Water enters most water
storage containers from the top; and the bottom of the storage container(s)
will need to be above the level of the garden beds to allow for gravity-fed irrigation.
So the water will likely have to pass over a walkway into the garden. Perhaps an entry arch between house and
vegetable garden? It could incorporate a downspout extension to convey water
from the downspout directly to the storage container(s). A nice
arch would also help to hide the maintenance area from view.
The runoff from the front roof also requires some thought. Most of the water currently runs into the
street – a waste of 400 gallons with each rainstorm. Our homeowners might consider building a
water infiltration system in their front yard.
For example, a dry swale would make the front yard more interesting while
allowing rainwater to percolate into the ground. The resulting deep watering might extend the irrigation-free
period each spring.
The gardeners at 112 Willow might also consider locating
a large water storage container near the downspout on the northeast side of the
house. A shrub or trellis could hide the
functional-looking storage container from the street. The water could then be used to irrigate the
‘meditation garden’ in spring and summer.
The gardeners decide they want the best of both
worlds: they will split the water from the NE downspout. Half will be saved and the other half will
infiltrate into the front yard. This
system won’t be implemented right away – funds and time are limited this year. But it will ultimately form an important
part of the water management system for the entire yard.
We’ve come a long way towards designing a water
management system. Next month (March
2014) we’ll explore designing an irrigation system, water features and pulling
the water management system together.
