Planting in the shade can be a real challenge especially if you are living in our neck of the woods (pardon the pun!). Our summers are hot and dry, whilst winters can be cold and wet. Our soil is either heavy clay or dune sand, and then we also have periodic strong winds coming from the west or south. Despite all the negative aspects mentioned above you can create a lovely garden under trees, or in pots positioned in a shady area. The secret is to improve the soil, to add potash, to mulch liberally and to choose the right plant for the right spot.
Remove existing soil.
If planting under established trees, remove the dry, nutrient deficient soil between the large roots, and replace with topsoil from another location in the garden.
Improving your soil.
Add loads of organic matter before you start, this will provide better water retention and better root growth.
Use potash to enhance the soil
Unlike the decomposed remains of leaves, stems and other green plant parts, burned wood doesn’t contain nitrogen. But it does provide phosphorous, potassium, calcium, boron and other elements that growing plants need. It’s also very alkaline and useful for raising the pH in gardens. You’ll need about twice as much of it as lime, but it will supply nutrients at the same time, and if you’re a wood-burner it’s free.
Sulphate of potash will also do the trick. It will promote tough, shade-loving plant growth. Never add high nitrogen fertilisers to this mix, saturating a garden with high nitrogen levels, does not improve plant growth. In fact, it can actually harm a garden more than leaving it to its natural elemental state. Too much nitrogen in plants is apparent both above and below the topsoil. Excess nitrogen fuels fast foliage growth so that your garden has an appearance of a jungle gone wild, but other plant growth suffers as a consequence. Energy for flower growth is redirected to foliage proliferation, so plants may not even produce their necessary reproductive organs during the growing season. The same applies to developing a poor root system.
Mulch area liberally with a thick layer of well-rotted compost of old bark chippings. Fresh wood chippings (which are essentially cellulose) from a felled tree, if spread on planted ground, will, at the very least, deprive the plants growing in that area of nitrogen for a while, since the bacteria responsible for breaking down the wood require nitrogen to function, so they rob it from the soil, leaving a shortage for plants.
For your garden to thrive, rather give a thorough soaking once a week than a superficial sprinkling every day.
Plants to consider for your shade garden:
Indigenous: Plectranthus species, Ferns, Clivia, Mackaya Bella, Haemanthus albiflos, Veltheimia, Streptocarpus, Chlorophytum, Hypoestes, Helichrysum petiolare, Sanseveria
Exotics: Ligularia, Bromeliad, Daffodils, Blue bells, Ferns, Fuchsia, Hellebore, Anemone japonica, Hydrangea, Camellia, Azalea, Strobilanthus