We get a lot of questions from our customer but one of the most common type of question we get is “will this plant cope in certain conditions”. Clay\sandy soils, coastal positions, high wind, frost, dry areas and shaded positions all take their toll in varying degrees on each variety of plant. We’ve put together a series of tutorials to you show how to deal with these difficult conditions and which plants may suit a given condition.
The first in this series will be dealing with difficult soils. We’ll talk about clay soils and how to improve the condition of your soil to get great results. This is by far the most common problem we get asked about.
Contrary to popular belief, clay itself can be very good for plants, it contains an abundance of nutrients that plants can use to thrive, the problem is that it doesn’t allow water to drain away from the roots. Most plants don’t like to sit in wet, boggy soil so clay will cause all sorts of problems.
The best course of action is to choose plants that are clay tolerant and will thrive in such conditions, such as the varieties listed below. But if you’ve got your eye on a variety that’s not so suited to clay, don’t despair, there are things you can do to improve your soil to allow for such plants. What you need to do will depend a lot on the type of clay you have and how much work you’re prepared to do to remedy the problem.
There are quite a few different tests you can do to work out what type of clay you’re dealing with but for the purpose of this tutorial, we’re going to try to keep it as simple as possible.
The first thing is testing for texture. Take a small lump of clay from your garden and add some water and work it in like you’re going to use it for pottery. Next, flatten out between your fingers in the shape of a ribbon, if you can flatten it to more than 50cm before it starts breaking up then you have a heavy clay.
Another test is the percolation test, this will determine how compacted the clay is. First dig a hole about 60cm deep and 30cm wide. Once it’s empty, fill it again and take note of how long it takes to drain out. If it takes less than 12 hours to drain, the soil should be able to support plants that require well draining soil. If it takes 12-24 hours to drain, the soil is best suited to plants that tolerate heavy or clay soils. If it takes more than 24 hours for the hole to completely drain only trees that withstand occasional flooding will survive.
Note: If you find Earth worms in your soil, then this is usually a great indicator of healthy soil
The aim is to improve soil structure by breaking down the clay to achieve looser, more granular particles and allow water to drain away but at the same time retain moisture and nutrients. The best way to do this is add as much organic matter as possible and as deeply as possible to the clay. Organic matter doesn’t only add to the nutrient content of the soil, it coats the clay particles and physically separates them from each other.
Another option is to add Gypsum to the clay to help break it down. This is somewhat less effective as not all clay types respond to Gypsum but there is a way to test it. Remove a small sample of clay from the garden and place it in a glass jar with clean water in it. Don’t touch the jar but take note of the water after an hour then after 24 hours. If the clay begins to disperse in the water making the water cloudy then your soil will respond to Gypsum, the cloudier it becomes the better the Gypsum will work. Gypsum can be added to the soil at a rate of around 1kg per square meter and should be worked into the soil, it would probably be a good idea to add in some organic material such as compost while your turning the soil.
Of course the best course of action is to try and find plants that will thrive in clay soils. Here is a list of suggestions we’ve found work.