Right, where were we? By now we have all of our site survey measurements and some piccies to go with it. We will need to draw up this measurements on a scaled plan soon but before we do that, we need to capture, and record, any other information about the site that is potentially important and relevant to the design process. This part is known as the site analysis and includes all non-measurable information. The information you gain here can be added to your final site survey plan, or you can do a separate plan. It will depend on how much information you find and how complex the plan is in the first place.
To carry out a site analysis you will need to pretend you have never been to your garden before. There may be things that you just don't notice any more, like a train passing by or excessive traffic noise. By pretending that you've never been here, you are more likely to notice things that you have become blind to. Of course, at times it will be helpful to remember things that occur in other seasons, for example, where bulbs come up in the spring and which plants provide good autumn colour.
You will need to 'get a feel' for the garden. To do this, don't just look at the physical landscape within the boundaries, but study the garden's surroundings. Where are you? Is your garden set amongst countryside, or woodland, or more town gardens? Are there any visible structures outside of your boundaries that affect the 'feel' of your garden. It can be good or bad, you need to observe and record everything!
Take a thorough look around your garden. Are there any elements that suggest a theme or would influence the new design? Are there features or materials that you would want to keep? Take a look at your house? Is it a particular style or period? You could use this style to influence your design. If you wanted to create a garden that was true to style, then visit a library, (or a search engine!) and research what gardens were like in the year that your house was built. If you want to, visit show gardens that depict designs from that period and seek inspiration. If you have a period house and want to include some historical elements to the garden, but don't want a complete restoration, then look at what materials were used then, or methods that were used. Including small elements of the period can work just as well to creating a link to the building as a complete restoration would. Another way to create a link between the house and the garden is to use similar proportions in your garden as are on the house facade. It is subtle, but will help your garden to flow, and make you feel at ease when you are in your garden.
An important piece of information to know is the orientation of your site. Which way does it face? Use your compass to establish in which direction magnetic north faces, and note this down onto your rough survey plan. You will also need to note what conditions are like on-site. Is part of the garden shady, gloomy, damp, a sun trap, etc? What shadows are cast by certain tress or buildings throughout a day? You can do a little exercise to find this out by choosing a relatively sunny day and making a study of how the sun moves around the garden at hourly intervals. Draw yourself another rough outline plan of your garden (doesn't need to be drawn to scale), and mark down any large features that may cast shadows (sheds, trees,etc). Each hour, sketch the areas that are sunny or shadowed onto your rough plan. Remember that the sun is higher in the summer and so you will get different shadows in your garden at different times of the year. The garden will have less light in the winter than in the summer. You will need to think of every season and how each element in your garden would be affected by them. By being aware of these factors you will be able to successfully chose plants that will flourish in your garden. If you observe moss or green algae on walls and steps it would suggest that there could be a drainage problem and this will need addressing too.
As well as considering physical factors you will need to observe environmental ones. A busy nearby road can cause noise and air pollution and may be something that you wish to improve when you come to create your design. There may be a local industry that creates pollution, and whilst it will not be possible for you to do anything about this, you can develop a design that will help disguise the problems.
You will need to know what type of soil you have (and no, saying it's muddy isn't good enough!). If you are unaware of your soil type and quality then any plants you try to grow will have a greater chance of failing.
All soils consist of four parts - inorganic materials, organic matter, air and water. It is the balance of these four parts that determine the quality and fertility of your soil. When analysing your soil you will need to record the texture and the pH level (pH means the potential hydrogen content, and tells you how acidic or alkaline your soil is). The texture of most garden soils generally fit into the categories of sandy, clay, loamy, chalky or peat. We find this out by examining the different particles that make up the soil. This is much easier than it sounds and simply consists of you rubbing a moist sample of the soil in between your fingers to determine its texture. Do this in several places in your garden, as the texture may differ in different places.
To tell what the texture is, here is a short description of the characteristics of each type:
Clay - the particles are less than 0.002mm in diameter. It is a fine textured soil that feels sticky to touch. In extreme cases you can work the soil into a shape and it will stay that shape! It is heavy to work with and is slow to warm up in the spring due to its high water content. It can be very fertile. In winter it can easily become waterlogged and in summer it becomes cracked and shrinks when dry. It's not all bad news though, as its make-up does hold many essential elements that are needed for healthy plant growth.
Sand - is gritty to touch. It is light and free-draining and warms up quickly in the spring. You will be able to work a sandy soil easily but its free-draining nature means that nutrients will be washed away quickly. As it loses water and nutrients easily, it tends to become acidic quite quickly and needs to have as much organic matter added to it as you can find. This will help to retain the moisture.Loam - steals characteristics from both clay and sand. It is moisture-retentive and fertile, but will compact easily. If you've got this soil then you are in an enviable position, as it is easy to work with and encourages healthy plant growth for a wide range of varieties.
Chalk - is pale and shallow. It is free-draining and fairly fertile but is very alkaline making your choice of plants limited. Nutrients get washed through quickly and you will have to work hard to improve it with the addition of rich organic matter and fertilisers.
Peat - is very humus rich and fertile. It is dark in colour and retains moisture well. It is a good growing medium but tends to be acidic and would benefit from the addition of loam and drainage material. You will need to focus on acid loving plants for this soil type.
Look at the diagram below. You will see that soil is made up of four layers;
Surface Layer - contains organic debris from leaves, etc.
Topsoil- where most living organisms (worms, grubs,etc) and highest levels of nutrients live. This is due to the surface layer of organic matter which releases nutrients into the soil below it. This is the best part of soil for growing plants as they will absorb the nutrients whilst searching for oxygen and water.
Subsoil - supports less life than the topsoil layer. It is usually firmer and more compacted and nutrients that have been washed through from the topsoil will settle here. You will usually find it lighter in colour than the topsoil as it supports less life. If you cannot notice much difference in colour between the topsoil and the subsoil, then it would suggest that your topsoil is deficient of organic matter.
Parent rock - supports no life and derives from rock that is local to your area.
To find out the proportion of each of these layers in your garden, it is usually sufficient to take samples of soil with a trowel and a plastic bag. Again, remembering to take samples from various places around your garden. If you need a better inspection then you can dig a soil pit. This hole will need to be large enough for you to see into it. Once you can see the colour of the soil, either by looking at the sample in the plastic bag or in the pit, you can determine what condition your soil is in. If the soil is dark brown or even black in colour then it would suggest that the soil is rich in organic matter, and if it is also well drained then it is likely to be rich in nutrients. If the soil is extremely black then it is likely that there is a drainage problem. A well-drained soil is usually brown to the depth of one metre. A soil that is completely waterlogged will sometimes turn a blue/slate kind of colour. If your soil is grey or white then it would signify that the soil is chalky or that it has had its nutrients washed out.
Now you should have a good idea of what type of soil you have and just how good its going to be at growing plants. You will also need to know it's pH level. The higher amount of Hydrogen present in the soil signifies more acidity. The lower the amount of Hydrogen present in the soil then, yes, you guessed it, the more alkaline the soil is.
The pH scale goes from 1 to 14 with acidic readings starting at 1. If you get a reading of 6.5 - 7 then you have a neutral soil. A reading of 13 indicates an extremely alkaline soil and so on. I'm sure you get the picture! Most soils in temperate regions will vary between the pH readings of 4 (acid) and 8 (alkaline). When you know your pH level of soil you will be able to choose the plants that will grow best in that soil type. Trying to grow an Azalea in a soil with a pH reading of 10 just isn't going to work!
The pH level controls the release of nutrients in the soil. The more extreme a pH level (at either end of the scale), the more plant nutrients are locked out of the soil. This will prevent the growth of certain plants. If you have a neutral reading then you are in the most fortunate position as most plant nutrients will be released and you can chose from a wider variety of plants. Although, if you were hoping to create a Japanese garden, you'll have to add ericaceous composts and feeds, else the plants just won't grow - they need acid soils.
So, you've read all of that and I haven't told you how to find your pH level reading! Easy. If you haven't already done so, go to your local garden centre and buy a pH soil testing kit. They will vary in price and sophistication but you can pick up simple ones that only cost a couple of pounds. Most of these kits give you an indication of the pH level by using a colour chart. When mixing water to the soil sample only use distilled water as this a neutral pH and won't affect your reading.
It would be advisable to take soil pH readings and texture samples from the same places on-site. You will be able to note down on your rough plan what each reading is. If you are running out of room on your plan now then you can number the positions on the plan and add a list on another page.
That's enough to be going on with for today. We'll continue to look at the site analysis tomorrow.
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