In the garden, trees, walls and buildings create areas of shade which cannot be avoided. This is a great advantage to create a quiet spot of greenery and mystery away from the heat of summer in the unsheltered parts of the garden.
The nature of the soil, rainfall, temperature and light are the four fundamental factors of plant growth. An almost infinite diversity of vegetation is created from an infinity of combinations of these factors.
Light influences the growth of the plant through the assimilating pigment chlorophyll; its absorption spectrum of light radiation is responsible for the plant's green colour.
This factor engenders multiple adaptations depending on the exposure:
We need to differentiate between the several types of shade or exposure to the sun:
In the garden, shaded areas can be at the foot of a wall, a border, near trees, in light or dark undergrowth beneath deciduous or coniferous trees. Not to mention the shade of other plants in garden beds that we should not forget to take into account in the examples above!
Primula officinalis (L.)
Flora von Deutschland (1885)
In most cases, the adaptation of plants, perennials or grasses, to poor light conditions entails less protection against heat and radiation. This means that partial shade plants transpire more, have lush growth and prefer moist, fertile soil.
Most partial-shade perennials prefer good, humus-rich garden soil, which is well-drained and constantly moist, even in the summer.
The best locations are those with a shadow thrown by a wall or a house or a tree planted a reasonable distance away. There is no competition between the roots of trees or shrubs and our beloved perennials.
Near trees, in a shady border or in understory beneath deciduous trees, bulbs associated with colourful foliage varieties of perennials or those with delicate flowers will provide a joyful display in the beautiful spring light. To complete the picture you can add grasses (Carex, Deschampsia, Hakonechloa, Imperata, Luzula) or ferns and foxgloves or Japanese anemones to prolong the summer.
If you are lucky enough to have a partial-shade area which is damp (if not, you can always devise your own swampy spot), the palette of available perennials widens to include those with greater luxuriance. Queen of the Prairie (Filipendula), Aruncus, Hosta, Eupatorium, Ligularia, Persicaria, Asian primroses with sumptuous candelabra flowers, etc.
Dense shade can be problematic for the gardener. Foliage limits rainfall and so the soil remains dry; the needles of conifers accumulate, forming a thick carpet and acidifying the soil; the roots of the trees form an entanglement in which it is very difficult to plant anything!
Under thick foliage, even in moist soil, few perennials can develop properly. However, let us note some ferns, sedges, Solomon's seals (Polygonatum), Deschampsia, the luzulas (Luzula sylvatica, Luzula nivea, Luzula pedamontana, etc.)
The worst locations are those with dry shade caused by competition among roots or a lack of rain.
Few plants can grow correctly in dry shade. Plants adapted to drought are rare: waxed and/or thick leaves(Asarum, Blechnum spicant, Carex morrowii, Cyrtomium, Epimedium, Luzula, Ophiopogon, Pachysandra, Vancouveria, Vinca, Waldsteinia), tuberous roots (Ophiopogon, Cyclamen, Liriope), succulents (Sedum spurium, Chiastophyllum).
However, it is possible to plant partial-shade perennials in dry shade as long as you water them regularly and limit the growth of competing shrubs. You can enhance the display by growing generous potfuls of more demanding partial-shade perennials (Brunnera,Heuchera, Hosta, Primula...)
Browse our selection : Dry shade perennials.
For more information and to refine your choice, try our advanced search engine to browse our different ranges: Dry shade perennials, low-growing shade or partial shade perennials, medium-height perennials for shade, tall perennials for shade.
Crédit : Plants for Shade (RHS Practicals), Royal Horticultural Society; Planting Companions, Jill Billington.