After an extremely dry and hot growing season, we are having to rethink our planting schemes. It is predicted that our summers will be typically on the dry side. Consequently, drought tolerant planting would seem to be the way to go. However, most of our soil is clay which can get rather wet in the winter, possibly too wet. Many of the typical ‘go to’ plants from the Mediterranean that are drought tolerant do not like getting their feet wet and require good drainage. In some parts of the garden the beds have been built up and raised thus improving drainage. So, we get away with some Mediterranean plants. The only real way to find out, is to experiment.
The next issue to address is extending the flowering season. Both Mediterranean and woodland gardens are at their best in the Spring and Early Summer when normally the soil is still moist. The woodland (dry shade) areas are the most problematic. Two plants that I hope will work are Fuchsia 'Riccartonii' and Hypericum calycinum. Both flower for a long time and are fairly tough. The Hypericum flowers best in full sun but should still put on a decent display in shade. We have had some success with Aster ageratoides asran and Eurybia divaricate. Unfortunately, the Japanese Anemones which have been in the garden for many years did not enjoy this summer in the slightest.
For areas that receive more light there is a great number of plants to choose from. Aster × frikartii 'Mönch' has performed very well in the paradise garden. It started flowering in mid-July and even without dead heading will hopefully keep going till gets frosted. In the main herbaceous border two plants have stood out for long flowering and shrugging of the drought. Perovskia atriplicifolia (now classified as a Salvia) and Saponaria officinalis. The Perovskia is often cited as being drought tolerant, the Saponaria I am not so sure about. Lady Crawshaw has intervened with some watering so I can not be sure how drought tolerant some of the herbaceous border occupants are. Persicaria amplexicaulis is normally long flowering and happy in clay soil. But like the Japanes Anemones and Hydrangeas it has suffered this summer. However, it will soon bounce back after some rain and like many other things will hopefully be back on form next year.
Another long flowering and drought resistant super star is the shrubby Salvia. There are a few species and hybrids in the mix, but my favourite is S. ‘Nachtvlinder’, a good dark purple and one of the more reliably hardy forms. S. ‘Royal Bumble’ and S. ‘Hot Lips’ have both performed well over a number of years. Selections of Salvia x jamensis tend to be the hardiest, shortly followed by other small leaved species such as S. microphylla. Buddleja x weyeriana selections such as B. x weyeriana ‘Moonlight’ flower for a long time particularly with deadheading. I am also found of the Buzz Series which again flower for a long time and are shorter plants at around 1.2m high. Flowering can be delayed till August if pruning is postponed till April. The plant looks tidier if flowers are removed when the bottom half of the panicle has gone over. Both B. x weyeriana and the Buzz series are near sterile, so self-seeding is not a problem.
Miscanthus sinensis is reasonably drought tolerant and will perform in clay. Being a grass, it adds a structural element to a border for a long season. Its flowers and seed heads add more interest in late summer and will persist into late winter. The long leaves of grasses are particularly useful to contrast with the typically small leaves of most flowering herbaceous plants. Sedum (now classified as Hylotelephium) is also a useful drought tolerant candidate for late summer, that will perform in clay soil, I particularly like the purple leaved forms such as S. ‘Purple Emperor’.
The changing climate is making it more of a challenge to keep the garden going. However, with some modifications we will strive to the keep the show going.
William Stanger of Four Winds Horticulture is a local Garden Consultant and international writer. He is advising Whatton House on the garden’s regeneration. He has worked at various gardens in the U.K and New Zealand including The Savill Garden and Dunedin Botanic Garden. He has a M.A. in Historic Designed Landscapes and a BSc Hons in Green Space Management.