Soil drainage is one of the most important things affecting the success or failure of your planting.
The soils most likely to be a problem are clay soils and soils with a shallow impervious subsoil such as solid clay or rock.
For all soils types
- When planting, don't dig a hole to fill with good soil as this will just create a basin for water to collect. Instead use the good soil to build up the level of the existing soil.
- If you are building up the level of the soil then a good quality sandy loam covererd with copious quantities of mulch is often better value for money than garden soil mixes.
- Water may be directed away from your garden by constructing shallow surface drains. These must be constructed with a continuous downward slope with somewhere for the water to go. If water is allowed to pond then it may just make the situation worse.
- Underground drains may be constructed by digging a trench and laying drainage pipe within a gravel bed. Again, the trench must have a continual downward slope with somewhere for the water to escape.
For clay soils and clay loams
The aim with these types of soils is to build up the crumb structure. This can be aided in a number of ways.
- Incorporate gypsum and lots of orgainic matter into the soil using a tilling machine or by digging with a garden fork. Alternatively, simply apply to the surface and cover with a good layer of mulch.
- Do not overwork the soil once you have planted and avoid practices which may compact the soil. Initially however, if the soil is very compacted then it may need some serious digging to loosen it up.
- Be aware that anything added to the soil which contains high levels of sodium can destroy its crumb structure. This may occasionaly include some municipal water supplies, waste water and even some mulches such as chicken manure. Gypsum however along with an occasional light application of magnesium sulphate (Epsom salts) can be very effective in counteracting the effects of sodium.