Woodland plants, the herbaceous layer in a woodland, with the tree and shrub layers above it, require a number of environmental qualities to succeed in gardens. Most of the European and North American plants are spring ephemerals; ie. they come up, flower and to some extent have their period of growth before the leaves are on the trees. Asiatic woodland flora is usually later flowering and often comes from a temperate monsoon type climate so usually grows through the season. To some extent we need a different growing situation for the two types. The first group will do well in a situation with shade and lots of spring and some winter moisture, drying up in summer. These are well suited to planting under trees and shrubs in shaded borders, and includes many of the spring treasures including snowdrops, Erythronium, Trillium, Sanguinaria and Primula. Asiatic species normally want the impossible moist but well drained soil with drier soil in winter and so do better in a raised bed with non-stagnant moisture retentive, humus rich soil, with constant shade from a wall or trees. This group includes many commonly grown garden plants such as Actaea, Thalictrum, Deinanthe, Ligularia and Meconopsis.
Many of the spring flowering species are plants that have fast periods of growth to flowering using reserves laid down the previous year. The longer these plants can be kept in leaf in the current year the greater the pay back the following year. So keeping them cool and not allowing them to dry up totally until midsummer will mean that the longer period of growth will pay back the investment used in the spring growth spurt, eventually excess reserves will be laid down so they will form clumps from single plants. Summer flowering plants including many of the Asiatic woodland plants will respond immediately and flower and grow better the same year.
Plants for Dry Shade
Many of the fibrous rooted herbaceous woodland plants from Europe and North America are amongst the most drought tolerant of the plants we can grow in shade. These include plants from Europe such as some Geranium sp, European Aquilegia sp., Lamium, Brunnera, Pulmonaria, Mellitis , Helleborus (particularly foetidus) and many of the native ferns as well as North American genera Tiarella and Polygonatum. The ultimate example is Ivy (Hedera helix), easy and tough as a woodland floor plant in the UK surviving through the driest conditions after the Spring ephemerals have dried up and died down for the Summer, it will tolerate almost impossible conditions in the garden.
Ferns will often tolerate very dry conditions particularly the male ferns (Dryopteris filix-mas), golden scale (Dryopteris affinis), soft shield (Polystichum setiferum) and hard shield (Polystichum aculeatum). They will often be found in damp spots but that is more to do with the moisture needed for the reproduction at the prothallus stage than the adult plant, by planting a young but adult fern and keeping it watered until the roots are established they can be grown in dry condition such as under hollies etc.
The other group for dry shade as mentioned above is the spring or should we say winter and spring ephemerals which includes many widely grown woodland bulbs but also plants such as Cyclamen hederifolium and Arum italicum.
Plants for Moist Shade
One the whole one can grow all those mentioned as examples for dry shade as long as the soil is not boggy and or sour ie anaerobic plus many of the choice plants from the Orient, such as many of the new introductions including Arisaema, Deinanthe, Hosta, Ligularia, Thalictrum, Actaea (particularly those previously cvs of Cimicifuga simplex), Asiatic Primulas and Asiatic Epimediums. Often planting on the north side of a wall with a humus rich soil will provide such conditions if one is not in the cooler moister parts of the country.
Ferns similarly the choice is wide and most will do well, the exception is with some of the very mossy Polystichum setiferum cultivars which can rot in a moist spot.
Planting Woodland Beds
Beds and borders need preparing in the normal manner, ie removing any perennial weeds and preparing the soil including any humus rich material you can get such as leaf mould or compost or composted waste from the council. Mushroom compost is often very alkaline and may need weathering first. Avoid planting in mid- summer or midwinter but containerised plants allow planting at any point. Keep watered until they are all rooted out.
Woodland plants on the whole want a low nitrogen fertiliser with an availability of trace elements and minerals, many are less pH sensitive than is commonly thought given an availability of nutrients