Whatever plants you are going to grow in your garden, you need the best quality soil possible. It should be well drained and aerated, with an ongoing supply of good quality nutrients. This may mean bringing in extra top soil; it invariably means adding compost and fertilizers to the soil.

Soil compaction

If you are establishing a new garden after building a new home, chances are you will have not only have lost a lot of your precious top soil, but what top soil there is left has been heavily compacted by all the machinery and building equipment on site during the building operation. Even construction of small garden buildings and features, or construction of amenities like decks, paths, walkways and patios can result in damage and compaction to the soil.

If soil is compacted, you can bring in an aerating machine that will open up small holes. This is particularly useful if the ground already has an established lawn on it. If the ground is bare, you need to get as much organic matter into it as you can. This will not only help to overcome the problems associated with soil compaction, but organic matter will also improve and increase the water-holding capacity of sandy soils and it will improve drainage of heavy, clay soils.

Another problem that often occurs during building operations, regardless of how big or small these are, is that established trees are threatened. If soil compaction around a tree you don’t want to lose is inevitable, or if it has already occurred, you can relieve the pressure, and prevent the roots from suffocating, by drilling holes into the ground from the trunk outwards, to the furthest line of leaves (which is where the roots will extend to). These should be about three inches in diameter and about a foot apart. Fill the holes with compost or with a mulch to which a root-promoting fertilizer has been added. This will allow water and air – as well as the fertilizer – to percolate through the soil and spread beneath the compacted soil and feed the roots.

Soil quality

There are three basic types of soil:

• Sand,
• Clay, and
• Loam.

While sandy soils drain well, they don’t retain the water. This means that you need to water (or irrigate) more frequently, and fertilize more often because the soil won’t have all the nutrients plants need to grow. Also, because the water flows quickly through this type of soil, the water takes what nutrients there are away with it. The best way to improve the quality of sandy soil is to add organic matter in the form of some sort of organic amendment, compost for example.

Clay soils are the opposite of sandy soils because they are heavy and thick, and they don’t drain well at all. You can lighten them by adding compost and some coarse sand. But be sure to add fertilizer for extra nourishment as well.

Loam is the best type of soil, because it drains well and contains nutrients. However this doesn’t mean it will necessarily have all the nutrients you need. For this reason it is always a good idea to test soil to see whether it is alkaline or acid. You can also have a professional soil analysis done to assess what nutrients need to be added to improve the quality of your soil. Or, just add compost to your soil. It’ll work wonders in buffering the pH of soil, and add the nutrients the soil is lacking.

Soil drainage

Roots of just about all plants need a constant supply of oxygen to survive and thrive. When drainage is inadequate, the plants won’t get enough oxygen, apart from which the soil will also tend to become waterlogged. While there are a few plants that will thrive in waterlogged soil – in particular anything that grows well in a bog garden, and a few trees including the gorgeous American sweet gum (Liquidambar styraciflua) – you will have to take some stringent steps to improve the soil. One way to do this is to build mounds or raised beds and to fill these with soil that does drain well. Alternatively, if it isn’t just the soil to blame, you might need to build in a piped drainage system or establish a French drain for water that flows from the garden.

Soil bacteria

All soil contains bacteria (which are single-celled organisms), even healthy soil. While we all fear pathogenic bacteria – the sort that cause horrible diseases – there are many beneficial bacteria. In fact bacteria, along with certain fungi, play a key role in keeping soil healthy. This is largely because they are able to help decompose certain materials.

Soil pollution

Soil pollution is the result of man’s activities that end up with chemicals and other harmful materials leaching into the soil. Polluted soil is not suitable for growing plants and trees. If your garden soil is polluted, you need to identify the source of contamination, rectify this and then remove the polluted soil and replace it with good quality top soil.

Helpful solutions to soil problems

Here are some more helpful hints and tips that will help you solve soil problems.

Soil testing kits are available for you to test how acid or alkaline the soil in your garden is. Alternatively you can take soil samples to a specialist laboratory and ask them to do the soil testing for you. A thorough soil analysis will tell you the levels of all the nutrients in the soil as well as identify the structure of the soil and pinpoint what the pH levels are. It is the pH (which indicates whether your soil is acid or alkaline and just how acid or alkaline it is) that most commonly needs correcting. The scale varies from 1 to 14, and if the soil is neutral, it will appear as 7 on the pH scale. Anything below 7 is acidic, and anything above 7 is acid.

Add lime to correct acidic soils. Add sulfur to correct alkaline soils – or a fertilizer with a good bit of sulfur in it.

Soil amendments range from aged steer manure to mushroom compost. When you prepare a new bed for planting, spread two to three inches of an amendment over the existing soil and then dig it into the soil to a depth of between six and nine inches, so that the amendment and existing soil are well mixed.

Soil preparation before planting always pays huge dividends. If you start with good quality soil, you won’t have problems trying to improve it later. But this doesn’t mean you won’t have to feed and fertilize. Soil maintenance will ensure that the soil quality remains good, and your plants will continue to thrive over time.

Always use compost to improve the quality of soil, whether it is sandy, full of clay, or even if it is a good quality loam. Organic compost has a certain magic that encourages earthworms and various micro-organisms to migrate into the soil. It also works well as a mulch.

If you make your own compost with compost bins, choose a three-bin system so that you have new material, mid-term material and compost that is ready for use.

Raised beds are a good solution for gardens where there is poor drainage. They are more effective than mounds and berms, because they have solid walls (either timber or masonry) that hold the good soil in place. To be effective, raised beds should be at least six inches, but preferably up to about a foot, deep. Drill holes in the base soil (as for compacted ground) before filling with good quality top soil.

Choose healthy plants so that they don’t contaminate the soil in the rest of the garden. Take cuttings from friend’s gardens by all means, just be sure the plants they come from are healthy and not diseased or infested with garden pests.