Last month we
envisioned your new garden: its overall look and the features you want to
include. If you’re just joining
the ‘Designing Your Colorado-friendly Garden’ series,
we suggest you start at the beginning (https://mothernaturesmontrosegarden.blogspot.com/p/creating-your-colorado-friendly-garden.html)
and work forward. The monthly activities will help you design an
attractive, functional, sustainable garden you’ll enjoy for years to come.
This month we take
the background information you’ve collected 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
July is Smart Irrigation Month, a good time to
consider garden water management. Water-wise, ‘smart’ gardening is a hot topic right
now. Unfortunately, there are many misconceptions about this subject. You might want to read our Sister blog’s
posting on the subject: Water-wise Gardening: Do I have to plant cactus or install
artificial turf? http://mother-natures-backyard.blogspot.com/2012/03/water-wise-gardening-do-i-have-to-plant.html
Local gardeners should seriously reconsider their garden water management. Climate change will almost certainly mean less water available for gardens. Coloradans should view recent 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, allowing more flexible irrigation schedules.
The Colorado-friendly 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 October, 2019 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 consider an
example of the basics of water management. We first presented our example
garden (112 Willow Street) last fall (http://mother-natures-backyard.blogspot.com/2013/07/designing-your-new-california-garden-2.html).
112 Willow represents
a fairly typical small Western yard (below).
It has lots of good features, which we already explored and mapped. We’ve conducted a functional analysis of the
garden and mapped functional areas https://mothernaturesmontrosegarden.blogspot.com/2019/11/creating-your-colorado-friendly-garden.html). Part of the mapping exercise involved
looking closely at the physical attributes of the site, including areas that
were naturally more dry and those that tended to remain moist.
As seen in the
questionnaire below, the owners 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 (August 2020). 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 4).
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 the
following:https://www.slideshare.net/cvadheim/water-zone-gardening
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 4). 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.
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 4. 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 2 (watered deeply several times a summer – no more than once
a month).
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 receive good precipitation (rain or snow) most winters;
we’ve located it in a low spot that tends to stay moist. But it will need some spring/summer/early fall
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 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 the area 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 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 Colorado-friendly Garden. We’ve
discussed several of them on our Sister Blog.
Hopefully you’re now
inspired to include some rain management methods in your own Colorado-friendly 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 Sister Blog’s posting on rain gardens and vegetated
swales (above). Calculating the amount
of runoff is fairly straightforward. Let’s assume that a good summer 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.
