Plants for Difficult Areas
We all have areas in our gardens where conditions are not ideal but even these difficult areas can support plants which are suited to those conditions. The trick is to choose the right plants by firstly understanding the problems of the site and secondly by knowing something about the requirements of the plants themselves.
Site problems are due to such factors as soil type, depth and fertility, amounts of sun or shade, angles of slope or position on a slope and degrees of exposure to weather elements such as wind and frost. As for the plants it is far better to grow plants which can, at least, tolerate the limitations of the site rather than force them to grow in conditions which don’t suit them. To this end it is always useful to have some idea about where the plants originated from and the conditions in which they grew in the wild. This is made a little more complicated by the fact that many wild genera and species have been altered by plant breeders and can seem far removed from their ancestors. Having said that, the genus name eg. Cistus or Hydrangea often still give the gardener some clues as to the requirements of the plants either from experience or from reference to the vast array of plant books available today. For example Cistus is also commonly referred to as the Rock or Sun Rose which suggests that they are from sunny areas with perhaps thin, stony soils. The name Hydrangea, on the other hand, seems to suggest an affinity to water and the experience of seeing Hydrangeas suffer quite badly in dry times confirms this. Plants also have a second name, the species name eg. Cistus hirsutus. ‘Hirsutus’ means ‘hairy’ and leaves covered with hairs are designed to reduce water loss from the leaf through transpiration which also suggests that Cistus are suited to hot, dry, sunny areas where soils to not retain water well. When the books confirm that they are from areas in S. Europe and N. Africa around the Mediterranean it is clear what conditions they like to grow in. In the case of Hydrangea macrophylla, the species name means ‘large-leaved’ which shows that the plant is able to transpire freely because of the availability of water. When the books tell you that Hydrangeas come from woodland areas in E. Asia and N. and S. America it becomes clear that they prefer damp, shaded conditions and why they do so well in Wales!
If basic Latin terms are ‘Double Dutch’ to you as they were to me when I first started gardening then don’t worry as there are other ways of establishing the conditions that certain plants prefer. The first port if call for most will be the plant’s label which should contain a written or symbolic description of the needs of the plant in terms of sun or shade, soil moisture and possibly soil pH (acidity or alkalinity). Then there is the plant itself which will be trying to tell you certain things. I have already mentioned that leaf size is quite a good guide- small or narrow leaves suggest sunny and dry while large leaves suggest a liking for damp conditions. The leaf colour can also help with grey or silvery leaves designed to reflect light and thereby reduce leaf temperatures and transpiration such as seen in Lavenders and Artemesias. Other water-loss reducing mechanisms in addition to hairy leaves are waxy or shiny leaves or spines instead of leaves as in the case of Cacti. As you get to know plants better they really will begin to tell you the conditions that they require but for goodness sake don’t tell anyone that the plants are speaking to you!
Finally I must mention some of the excellent books often by well-known gardeners which emphasize the idea of choosing the right plant for the right place. For example I have a book by the great plantsman, Roy Lancaster, which is aptly named “Perfect Plant, Perfect Place” (ISBN 0-7513-3592-4) which brilliantly matches plants to their preferred conditions. I also used to have a book by the wonderful Beth Chatto concerning her famous Gravel garden (unfortunately I lent it to a friend and for one reason or another never got it back!) She developed this garden on a former car park on very poor soil in Essex, one of the driest parts of the country. The soil was dug over and organic matter added, the right plants were then chosen, they were watered well on planting, mulched with a thick layer of gravel and never watered again! Most thrived and began to self-seed and the whole thing was a great success, adding a whole new group of plants to her existing garden which was partly in woodland and around some streams and pools which obviously had a very different array of plants. If a really difficult site such as this can be transformed then there is hope for us all and maybe we should look upon so-called difficult areas as opportunities to try something different rather than seeing them as a problem.
I will continue then with this theme of hot, dry, sunny areas which often have poor, thin, sandy or gravelly soils which also applies to sunny banks and slopes where water drains away quickly. Many plants which are adapted to these conditions come from Mediterranean or mountain areas or other places with hot, dry summers. Many of them are evergreens with small, often grey or silvery leaves or with hairs and spines as I have already suggested. Several have an added bonus of having scented flowers or foliage and such plants include:-
Shrubs– Ceanothus, Cistus, Cytissus (Broom), Hebe, Hibiscus, Lavender, Parahebe, Rosemary
Perennials– Achillea, Armeria (Thrift), Artemisia, Dianthus, Erigeron, Eryngium (Sea Holly), Erysimum (Wallflower), Euphorbia, some Geraniums, Thyme, Verbascum
Bulbs– Allium, species Tulips eg. Tulipa tarda
I have mentioned our own gravel area which contains quite a few of the above in previous blogs. Although on nothing like the scale and scope of Beth Chatto’s garden it does, I think, show what can be done with what at first seems to be a problem area. On moving into our house in West Wales in the spring of 2017 we were faced with quite a large area of decking. Now I don’t propose to get into the pros and cons of decking which for many is a ‘Marmite’ subject- you either love it or you hate it! Suffice it to say that we had too much of it so we removed one section, gave the wood to the friend who did the removal and were then faced with what lay beneath! We exposed a rectangular area edged with mainly broken paving slabs and what had possibly been a pool in the centre although there was no evidence of standing water. A pool would have been nice but unfortunately and I think you can guess what is coming next, the area had been used as a dumping ground for a mixture of bricks, more broken slabs, patches of soil, sand and gravel and some green waste from the garden. As we had plenty of work to do inside the house we decided to work with what we had rather than to dig the whole area out and start again. So we broke up the rubble as best we could to give a very well-drained base layer and covered it to a depth of not much more than 6 inches (15 cms) with a mix of soil, compost and some lawn turf which we had from re-shaping the lawn. This was then covered with a weed supressing fabric sheet which we planted through by just cutting a cross shape and folding back the fabric. We then added a few pieces of slate as stepping stones before the whole area was covered in a 2 inch (5 cms) layer of gravel. We have been delighted with the results and as the photographs show it even looks reasonable in November! It just goes to show that by choosing the right plants for the conditions a difficult site can be made into a real asset. However, nothing is ever perfect and we had our share of failures something which reminds us that gardening is often about trial and error. I was sure that one of the plants which would do well in these conditions was Thyme which would love the sun and the thin, well-drained soil. I had visions of a carpet of different colours covered in bees in the summer. Unfortunately the plants hadn’t read the script and one by one they gave up the ghost and died on us. I think it is just too wet for them in the winter in this part of Wales despite the well-drained subsoil. However, other plants have loved the conditions and have done so well that we have now reached the stage when some need cutting back, something which we will leave until the spring. I have mentioned before Erigeron karvinskianus ‘Profusion’ with its small, daisy-like flowers and Persicaria affinis with its spikes of pink flowers as well as several grasses which seem to do well here. However, the real success has been the Parahebes of which there are now three. These as the name suggests are related to their larger cousins, the Hebes, and like them are from Australia and New Zealand occurring in sunny, dry and stony habitats. They are evergreen and mat-forming, ideal for gravel gardens and although the flowers are small they are produced in large numbers over long periods in white, pink, lilac and blue depending on the species.
One of the Parahebes in November sunshine!
A second problem in gardens can be caused by poor drainage and at times too much water. These areas often occur at the base of slopes and/ or on soils with a high clay content. Clay particles are very small and therefore the gaps between them are small which restricts the movement of water. If spaces are permanently filled with water and no or little air is present then only specialist marginal or truly aquatic plants will prosper and I will be saying more about these in the mid-December blog on ponds. However, most damp soils do have a mixture of air and water except when waterlogged perhaps for a few days each year and as a result a good number of plants will thrive in these conditions. They do, however, look very different to the ‘Dry Group’ of plants mainly because they have much larger leaves. Plants suitable for moist areas would include:-
Trees- Alnus (Alder), Betula pendula (Silver Birch), Salix (Willow) but not a Weeping Willow unless it is well away from the house! and Taxodium (Swamp Cypress).
Shrubs– Cornus (Winter stem) and Hydrangea.
Perennials– Astilbe, Iris, Lobelia ‘Queen Victoria’, Lysichiton (Skunk Cabbage), Lysimachia, Lithrum, Minulus, Primula, Rogersia.
Ferns– Matteuccia struthiopteris (Shuttlecock Fern), Osmundia regalis (Royal Fern).
Bulbs– Fritillaria meleagris (Snake’s Head Fritillary).
Our wettest section of the garden is the lowest lying corner which water naturally drains down to, although I have to say that as I write this on a particularly wet weekend all parts of the garden are absolutely soaked! This particular corner is dominated by a large, lacecap Hydrangea which clearly loves the moisture and it never suffers from wilting leaves which Hdyrangeas can suffer from in areas with drier soils.
A third so-called difficult area that many of us have somewhere in the garden is the shady patch. Some such areas are due to being shaded from the sun by fences, walls or buildings for much or even all of the day. Except right next to the screen the soil usually remains quite moist because of the reduced evaporation and there are many plants which do well in such situations including those, apart perhaps for the trees, in the list above. Such areas, I believe, should be considered an asset rather than a problem because they allow the gardener to grow a wider range of plants. Good plants for this damp shade would include:-
Shrubs– Hydrangea, Mahonia, Sarcococca (Christmas Box), Viburnum.
Perennials– Ajuga, Anemone nemerosa, Brunnera, Digitalis (Foxglove), Epimedium (Bishop’s Hat), Helleborus, Pulmonaria, Thalictrum, Tiarella.
Ferns– Athyrium (Lady Fern), Polystichum.
Bulbs– Galanthus (Snowdrops), Hyacinthoides non-scripta (English Bluebells- please not the Spanish Bluebell!)
Other shady areas, however, are a bit more of a problem. These tend to be under trees and larger shrubs which not only take up a lot of water from the soil but also, particularly in the summer, prevent rainfall from reaching the soil under the leaf canopy. This ‘Dry Shade’ is not an easy place for a plant to thrive in and this list is therefore more limited. Having said that there are still some good plants even for these areas. Spring bulbs are particularly good as they grow and flower while the soil is still moist and before the leaf canopy is full. They then die down and lie dormant through the summer. Larger, more permanent plants can do well if they are given a good start with lots of organic matter added at planting and afterwards annually as a mulch (as would happen naturally in a woodland) to help hold moisture and watering in the first few months to help them establish. Such plants include:-
Shrubs– Aucuba (Spotted Laurel), Evergreen Euonymus, Kerria japonica.
Perennials– Bergenia, Geranium macrorrhizum, Helleborus foetidus (Stinking Hellebore- don’t worry it is only the root that’stinks’), Iris foetidissima, Lamium (Dead Nettle), Vinca.
Ferns– Asplenium scolopendrium (Hart’s Tongue Fern), Dryopteris filix-mas.
Bulbs– Cyclamen, both hederifolium and coum, Galanthus, Hyacinthoides non-scripta.
Finally some parts of gardens are more exposed to the elements than others, especially to strong, cold winds. The key here is to choose plants which are small and compact so that they keep ‘below the wind’ and there suffer much less damage if any. Large-leaved plants are best avoided as they damage far too easily, as are early flowering plants which are particularly susceptible to frosts or chill winds. In really exposed areas the creation of shelter belts using hardy, often native, trees, shrubs and hedges may be necessary before introducing the more ornamental plants. Such plants might include:-
Shrubs– Berberis, Calluna (Heathers for acid soils), Chaenomeles (Japanese Quince), Deutzia, Erica carnea and E. darleyensis (Heathers for all soils including neutral and even slightly alkaline), Potentilla, Spiraea, Tamarix, Viburnum opulus.
Perennials– Aster alpinus, Dianthus.
In the above I hope I have covered the main problem areas which we gardeners have to contend with but I also know that there are many more. The main thing is to view the problem as an opportunity to grow some plants which you perhaps wouldn’t normally think about and which can make your garden even more interesting. Easy to say but difficult to do I hear you say but why not give it a try? If you have other garden problems which I haven’t mentioned please feel free to ask about them by sending in your questions in the contact space below the blog or if you would prefer it get along to your local, friendly garden centre where I am sure you will get plenty of good advice.
The next blog will be at the beginning of December when I will attempt to get you to at least look out at the garden even if you don’t feel much like getting into it! Unlike ‘Gardeners’ World’ this blog doesn’t stop for the winter!
Until then keep safe and try to keep gardening!
Keith