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Saturday, August 31, 2013

Designing Your ‘New California Garden’: 3. Site Physical Assessment

 

As we discussed in our introduction (July 2013), the ‘New California Garden’ involves designing a home garden around existing conditions – what we like to think of as a site’s ‘natural assets’. This series is aimed primarily at California gardeners, but the principles are applicable wherever you live; they are, quite simply, the principles behind sustainable gardening. The key point is this: get to know your garden’s ‘natural assets’ then choose plants and hardscape appropriate for these assets. The result is a healthier, more sustainable and often more interesting landscape.


Site physical conditions will be different for each garden; that’s why each gardener needs to discover his/her site’s own assets before considering a garden design. Site characteristics include such things as soil type and drainage, sun and shade patterns, wind, temperature and even views (good or bad). You need to assess these site assets before you plan your garden so you can take advantage of them. This post will walk you through the process.

Several physical characteristics have the most effect on plant suitability and plant health. These include: precipitation and precipitation patterns; soil texture and drainage; the amount of light (sun and shade); temperature; and wind. We discuss each of these in a separate section, below. You will find there’s lots to learn about your garden – information that will actually make your gardening easier.

By the end of this exercise you will know a lot more about your site. You will carefully observe conditions in your yard; you’ll also conduct some simple tests. We suggest you complete several summary sheets with key information about your site. The summary sheets are available at:
http://www.slideshare.net/cvadheim/physical-characteristics-of-your-site-summary (site summary) and http://www.slideshare.net/cvadheim/soil-characteristics-of-your-site-summary (soils summary). You will also create several maps that will help you design your garden on a solid basis: a soils map (if needed); a sun and shade map; and a map (or two) with other physical features. If you don’t yet have a good base map for your garden, see our July posting: Designing Your New California Garden: Creating a Base Map.




1. Yearly Precipitation





Nothing influences plant growth like the amount and pattern of precipitation. You probably have a basic understanding of precipitation in your area. But as climate changes, and water becomes more scarce (at least in the U.S. Southwest) you need to take a careful look at precipitation patterns over time.
 
Yearly climate data is readily available on the internet. Local television channels or the Weather Channel have some good information on average temperature and precipitation for your area. If you live in the U.S., NOAA has good climate information – including historical data - at :
http://www.ncdc.noaa.gov/new-climate-information.

As you know, precipitation can vary widely by geographic area. Consider purchasing an inexpensive rain gauge and tracking precipitation in your own backyard. Check with your neighbors. You may have a helpful neighbor with precipitation records going back years or even decades! These will provide a better indicator of your neighborhood’s precipitation than any other source.
Note the precipitation information, and its source, on your Site Summary Sheet (
 
 


2. Soil type and drainage.

After precipitation, soil type and drainage have the most effect on plants. If you haven’t read our series on ‘Getting to Know Your Garden’s Soil’ – Sep 2012-Jan 2013, we suggest you start there. To skip directly to soil evaluation and testing, our posting on Getting to Know Your Garden’s Soil: Simple Soil Tests (Oct. 2012 is available at http://mother-natures-backyard.blogspot.com/2012/10/getting-to-know-your-gardens-soil.html

After you complete your soil and drainage evaluation we suggest you complete the soils summary sheet (


 


3. Sun and Shade.

Three main factors influence how well a plant will do in a given location: soil moisture, temperature extremes and the amount of sunlight/shade. We tend to think of CA native plants as being ‘sun lovers’, and this is true for most plants in some plant communities (for example, desert communities). But most California plant communities include a combination of sun- and shade-loving plants. The Shade-lovers will be found growing in the shade of trees and shrubs, in the bottoms of canyons or forests and on north-facing slopes.

There are many degrees of shade – both in nature and in the garden (definitions are given below). The trick is to match the light requirements of the plants to those of the garden. Shade is often viewed as a deterrent to gardening, which is unfortunate. While shady areas do present unique challenges, lovely native plant gardens can be created in lower light environments. In fact, shade gardens have many special attributes and advantages.
  • The lower light intensity creates a calm, peaceful atmosphere, a restful place.
  • As the hot sun beats down, toasting the ground and wilting everything in site, a lush green shade garden becomes a paradise, a refuge from the scorching temperatures of a summer day.
  • Shady spots are more enjoyable to work in during the heat of the summer.
  • Depending on the site and plant selection, these sites may require less watering as there is less water evaporation.
  • In a shady garden the play of light and shade, ever-changing throughout the day and from season to season, adds to the beauty of the garden.

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Creating Your Light & Shade Map - Mapping light zones in your garden
To really understand your garden’s patterns of light requires close observation, ideally in winter, spring and summer. Mapping your garden’s light conditions means you'll need to spend some time outside in your yard. Of course, you could break this down into three or four parts over three or four days; on the other hand, this is a great opportunity to really enjoy being outside. Even if you think you know your garden we guarantee you will be surprised by your results! And once you’ve created a good Light & Shade Map you will find it much easier to select suitable plants.

While you may be tempted to just guess at the light conditions, we highly recommend taking the more methodical approach. Our own experience taught us that while we thought we knew our gardens’ shade, we really didn’t! We found that unless you actually observe the shade patterns, you may forget crucial factors such as the shade cast by walls, umbrellas and other shade-makers; or underestimate the amount of morning sun hitting plants under your trees.

Start with a copy of Base Map 2. You will map the shaded areas at 9:00 a.m, noon and 3:00 p.m. Note the date of the shade map since light and shade patterns vary with the season. At 9:00, noon and 3:00, draw a line roughly showing where the sun is touching still (or where the shade begins) in each area of the yard. Note also areas of Deep shade and High/dappled shade (see table below for definitions). At the end of the day you'll be able to construct your final Light and Shade Map, which maps the shade regimens for each area of the garden. See an example, below, of a Shade Map done on August 21st .


 
Bear in mind that some factors affecting sunlight patterns will change during the course of the year. So, to really understand the light patterns in your garden you may want to re-map your garden in summer and winter.
 

Common Terms used to Describe Light Conditions in the Garden





 

Term
Description
Notes for your garden
Reflected sun with heat
A south facing wall that can break 130 F on a good day, like a south wall in Bakersfield,  Palm Springs, even parts of the inland valleys & inland empire.
This is a pretty tough regimen for most plants.  Only plants from desert communities can survive.
Full sun
A reflective wall in the mountains or cooler areas along the coast; full sun everywhere else (at least 6 hours/day).
Many plants from Coastal Strand, Coastal Prairie/shrubland, Coastal Sage Scrub, Chaparral, Oak Woodlands, open Forest
Afternoon sun
Can be a challenge in the interior, nice near coast.   Often along walls.
Plants that can take heat – chaparral & desert communities
Morning sun
Good light; not as hot and intense as afternoon sun.   Fine for plants that like partial shade.
Ribes, Heuchera and many other north slope plants tolerate this exposure.
High/Dappled Shade
Shade created by tall, open trees or a north-facing wall. Fairly bright light, but direct sun is minimal for any length of time.  A wonderful type of light!
Hospitable to many sun and shade loving plants from nearly all plant communities.
Part-shade/ Shade
No direct sun for at least half the day.  Darker than high shade – often on N side of taller buildings.   Shade-loving plants.
Shade-loving plants, primarily from Oak Woodland, Riparian and Forest Communities.
Deep shade
Quite dark the entire day - for example, under very dense evergreens.  Not much grows here.
Forest floor plants that require very low-light conditions.  More likely plants from N. CA or Pacific Northwest

 

 
 
 
 
 

 

4. Temperature and Temperature Patterns

Local temperature information is readily available on the internet for many areas. We suggest downloading a table or graph of the average monthly high and low temperatures for your local area. This will help you realistically plan your garden. It will also let you know when you’ll likely be able to plant in your area.

As with precipitation, temperature can vary greatly over short distances. In fact each garden has its own temperature microclimates, influenced by buildings, walkways, plants and physical structures as well as wind, shade and other factors. You may have already noticed areas that are warmer or cooler than the rest of the garden. You can use temperature microclimates to your advantage by planting plants that require more – or less – heat than is found in the rest of the garden.

Get out into your garden and notice the temperature patterns. If it’s summer, now is a good time to discover pockets of heat in the garden. If it’s winter, observe which areas are noticeably warmer or cooler (there may be as much as 10° F (5° C.) differences across the garden). Note the differences on your Site Summary Sheet and map the areas on your map (see example, below).

 

5. Topography and Drainage
 
Landscape topography refers to the high and low places in the garden. High points may be as dramatic as actual hills or the tops of steep slopes. More often they are subtle, representing elevation changes of only a few feet. Low places in some gardens may include natural canyons, streambeds or the bottoms of steep slopes. In many gardens the low areas also are subtle – but they are enough to affect drainage patterns. The topography may be either natural or man-made.


 
Landscape topography is most important for its effects on soil moisture. You may have noticed low areas in your garden that tend to retain moisture longer – or high areas that dry out more quickly. You’ll want to take advantage of these differences in topography by planting species appropriate for the soil water conditions they provide. The first step, of course, is to map significant garden topography on your Physical Features Map (see example, above).

To learn more about site topography see our posting Getting to Know Your Garden’s Soil: Soil Topography (Dec. 2012).




6. Wind Patterns
Wind can play an important role in some gardens. Some areas have high winds at certain times of the year. Other areas may have cooling sea breezes most afternoons. Still other gardens may experience hot, dry winds in the fall or spring. All of these wind patterns may influence the type of plant that will thrive in your garden.
Wind also provides air circulation. This is often a good thing, particularly in gardens where soil moisture can provide the perfect conditions for garden fungi during warm weather. Get out in your garden and observe wind/air flow patterns over several days. Be sure to observe these patterns at different times of the day. Are there areas that are particularly breezy? Areas where the air doesn’t move at all during the day? Map these on your Physical Features Map.
Think about the yearly patterns of wind in your area. Are their times of significant high winds? Have these effected local gardens in the past? Note this also on your Site Summary Sheet. You’ll need to plan for wind when you design your garden and choose your plants.
 

7. Other Physical Features

Other physical features include anything else that will influence your landscape design. These will vary greatly from site to site. One yard may have commanding vistas that should be featured in the landscape design. Another may have unsightly views which should be screened. These features (and any other physical features) should be mapped on your Physical Features Map.

Some sites have unique physical features that could be highlighted in the garden design. These include cliffs, large rocks/boulders, natural outcrops, ponds, streambeds and many other features. You may want to design your entire garden plan around significant physical features. Include any such features on your map.


We value your comments (below). You can also contact us directly at mothernaturesbackyard10@gmail.com.

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