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Cornucopia - How to deal with dry shade

How to deal with Dry Shade
Joe Sime

Many gardeners fail to see a shady spot as the horticultural blessing that it is. In particular they struggle with dry shade. If you are one of these then just try the easy step-by-step guide below.

  1. START
  2. Is the soil bone-dry even in the winter and early spring? If ‘Yes’ go to (12)
  3. Is the soil good i.e. with reasonable humus content? If ‘Yes’ go to (9)
  4. Are you willing to put some effort into improving the soil? If ‘Yes’ go to (8)
  5. Are you willing to mulch? If ‘Yes’ got to (7)
  6. Your planting options are limited to list 1. Even so you must plant the plants in the early spring when the ground is moist and you must be willing to water the individual plants during the first summer until they are well established.
    STOP
  7. You have a choice of mulching methods dependent on the size of the area and the depth of your pocket. For largish areas a layer of planting fabric topped with a thin layer of bark or composted wood chippings is cost effective. However this prevents the easy spread of rhizomatous plants. More effective is a deep (>4 ins) layer of composted bark or wood chippings. This has the added benefit of gradually improving the soil, but will need replacing occasionally as it decays. Having mulched the area you can use plants from both lists 1 and 2.
    STOP
  8. DO NOT DIG! The worst thing you can do to improve soil in shade is to dig it. This can damage the trees and shrubs forming the canopy. It also causes them to grow new feeding roots where their roots have been damaged, and these suck more of the little moisture you have from the soil. You must build up a layer of good, humus-rich soil about 10 ins deep. The ideal is a mixture of equal parts of sandy loam, leaf-mould and mini-chipped bark. A good alternative is a mix of sandy loam and garden compost. If you have or can borrow one, a small cement mixer is useful for large areas. If not then apply each in thin layers and let the worms do the work of mixing.
  9. Are you willing to water in the summer? If ‘Yes’ got to (11).
  10. You must mulch the soil, either with planting fabric or with a good layer of composted bark or wood chippings. Having done this you can choose plants from list 3 in addition to those in lists 1 and 2.
    STOP
  11. By far the most economical and effective method of watering is to lay a length of ‘leaky hose’ with a connecting nozzle hidden under a rock at a spot convenient for you to reach it with a line from your water supply. The whole area should then be covered with a thick layer of mulch (chipped bark or wood chippings). Water at a trickle over-night for best effects. You can now add most shade plants to those in lists 1, 2 and 3. Some good ones are given in list 4. The only plants off your list are those that require very sharp winter drainage.
    STOP
  12. This usually means overhanging, impermeable shade either from buildings or dense evergreens. Do not fight the inevitable. Cover with bark, gravel, paving or decking. If you really want to grow something then buy pots or build planters. Fill these with a mix of equal parts of sandy loam, leaf-mould and mini-chipped bark. Water well in the spring and summer, sparingly in autumn and not at all in winter and you can grow some of the aristocrats of the shade world. Examples are shown in list 5.
    STOP

Plant Lists
The costs of printing alone mean that we must limit the lists to only a few plants. Therefore in list 1 through 4 I have included only a few each of shrubs, large perennials, medium sized perennials and small/ground cover. List 5 contains a few relatively easy ‘unusual’ plants for a specialist shade planter.

List 1
You are mainly limited to plants from the woods of continental Europe and the western USA.
Shrubs: Ilex, Ruscus.
Large perennials: Aruncus dioicus, Trachystemon orientalis, Lunaria rediviva.
Medium perennials: Iris foetidissima, Geranium macrorrhizum, Luzula species.
Ground Cover: Epimedium pinnatum subsp. colchicum, Rubus 'Betty Ashburner'.

List 2
Slightly less dry soil in the summer widens your choice a little.
Shrubs: Crinodendron hookerianum, the common Mahonia varieties, Euonymus fortunei varieties.
Large perennials: Geranium palmatum, Aconitum varieties, Lamium orvala.
Medium perennials: Geranium renardii, Bowles golden grass, dry tolerant ferns such as Polystichum species.
Ground cover: Common epimediums eg E. x rubrum, Vancouveria hexandra, Lamium maculatum varieties.

List 3
A good, moisture retentive soil starts to open up the options to some really good plants from Europe and some of the easier ones from North America and East Asia.
Shrubs: Itea, Pieris.
Large perennials: Campanulas, Carex pendula.
Medium perennials: Hellebores, heucheras and related genera.
Ground cover: Erythronium, wood anemones, Cardamine.

List 4
Reliable summer moisture makes all the difference.
Shrubs: Rhododendron, Hydrangea.
Large perennials: woodland lilies e.g. Martagon, Maianthemum, Kirengeshoma, most ferns.
Medium perennials: Trilliums, Actaea, some Arisaema eg candissimum, speciosum, consangineum.
Ground Cover: Roscoea, choice epimediums, Asarum species.

List 5
A good, deep humus rich soil, summer moisture and winter drainage with no overhead sun mimic the conditions in the woods of the Himalaya and East Asia. Try: woodland orchids including the easier Cypripedium, Arisaema eg griffithii, sikokianum etc., Deinanthe, Paris, Cardiandra, Glaucidium, Chloranthus etc., etc.

First published in the Shropshire Group Newsletter, January 2010
and subsequently in Cornucopia Issue 27.
© Copyright for this article: Joe Sime

This article was taken from a copy of Cornucopia that was published in 2011. You could be reading these articles as they are published to a national audience, by subscribing to Cornucopia.


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