Trees are invaluable in the garden, adding much to its character and structure. However, planting beneath them can be a tricky business, with shade-casting canopies combining with moisture competition from tree roots. Areas on the north and east sides of trees can be even drier and shadier than other aspects.
Pulmonaria - photograph copyright T.Sandall Measures to improve the soil prior to planting can make the difference between success and failure. Adding bulky organic matter will help provide a reservoir of moisture for developing plant roots, while a well-balanced base fertiliser replenishes impoverished soil.
Organic mulches, renewed each spring, will also assist where tree roots are shallow and dense.
Autumn planting under deciduous trees takes advantage of the lack of leaf cover, allowing plants to get established. After planting be particularly vigilant of watering, since new plantings will be more prone to drying out than usual.
Lamium maculatum (deadnettle) - photograph copyright T.Sandall Woodland dwellers form the majority of plants suitable for growing beneath trees. Many look delicate in flower but groundcover plants such as lily of the valley (Convallaria), deadnettle (Lamium maculatum), Epimedium and violets (Viola odorata) are surprisingly robust. Other good ones for carpeting larger areas include Bergenia, Brunnera macrophylla, Galium odoratum, Geranium macrorrhizum, Tiarella cordifolia and Vinca major. For a splash of colour plant Liriope muscari or Iris foetidissima.
Some trees can be harder to plant under than others. Conifers are notorious for their dense evergreen canopy, propensity to dry out the soil and impenetrable, often acidic leaf litter. Such inhospitable conditions will support little plant growth unless the canopy can be opened up.
Even then, only those suited to deep shade will survive. These include a range of native shrubs; box (Buxus sempervirens), yew (Taxus baccata), holly (Ilex aquifolium) and spurge laurel (Daphne laureola). Other toughies include ivy (Hedera helix and H. hibernica), butchers broom (Ruscus aculeatus), Mahonia aquifolium, and Gaultheria shallon.
Alchemilla mollis - photograph copyright T.Sandall Deciduous trees such as beech, hornbeam, birch and oak can be underplanted with spring bulbs. These have usually finished flowering by the time the trees come into leaf. Provided the ground can be made moisture-retentive with humus-rich mulches, bulbs like Cyclamen hederafolium, bluebells, snowdrops and Narcissus bulbocodium should naturalise around the base of tree trunks.
