Most gardeners have some narrow borders to deal with, particularly those gardening in small spaces. Maybe you have a strip of land alongside a fence or wall, at the edge of a patio, or between a path and a boundary? Even those with sufficient space have a habit of making the beds too narrow, often in the belief that flower beds mean hard work, while grass is easier to maintain. In reality this is far from the truth.
So often medium sided shrubs are planted in beds that are too narrow to accommodate them. This results in futile work: the constant task of cutting back the offending plant in an attempt to make it fit the space. The plant is the innocent party - the planting space simply wasn't large enough to accommodate it. The same is true of herbaceous perennials that start the season as a nice n Eat clump of fresh shoots and them quickly expand into a billowing mound that encroaches onto pathway or lawn. The effect can be ruined in an attempt to contain their natural inclinations.
Euonymus japonicus 'Green Spire'
The answer is to choose plants that go up, rather than out. Narrow and fastigiate shrubs such as Euonymus japonicus ‘Green Spire’, an upright evergreen for any growing conditions. This will contribute solid structure amongst tall, slender, self-supporting perennials and annuals and climbers. Use the vertical space and suppress any inclination to keep your plants in check at a low level. It's also worth mentioning the importance of not planting too close to the edge of the border. This is a common mistake made when planting herbaceous perennials. A reasonably compact geranium such as 'Johnson's Blue' planted a few inches away from the edge of a lawn or path will soon encroach. Plant it further back if possible and use the available space. If the planting area in narrow it is worth alternating taller and shorter subjects along the border to take advantage of the available ground.
Euonymus fortunei 'Emerald Gaiety' and Hedera colchica 'Gloire de Marengo'
Slender perennials that grow straight up from a rosette or clump of leaves are ideal to add seasonal height. Digitalis lutea is a good example. Delicate, slender spikes, self-supporting growing from plants with an unassuming footprint. This is a plant which does not flop and sprawl. It stays neatly within bounds.
Some penstemons such as Penstemon ‘Raven’ are also very upright and ideal in narrow beds. They have the advantage of being evergreen with woody stems that need no support. They flower from midsummer through to late fall and require little in the way of maintenance apart from dead-heading and a tidy up after winter.
In dry, sunny borders verbascums are a good choice, especially the shorter varieties with smaller leaves. Verbascum ‘Jackie in the Pink’ will fit into the narrowest space and will overwinter surprisingly successfully on well-drained soil. The branched but upright flower spikes are extremely attractive and bloom for weeks. It’s lovely with silver foliage shrubs and lavenders, all good choices for sunny, dry narrow beds.
Verbascum 'Jackie in the Pink'
The Russian sage, Perovskia ‘blue spire’ likes similar situations. The silver stems can become rather lax and floppy on damp, fertile soil but stay sweepingly upright in sunny, dry spots. It can be very effective in a narrow border along the base of a wall or fence if under planted with something to provide ground cover.
Perovskia 'Blue Spire'
If the narrow border is backed by a wall or fence then this is a great opportunity to use climbers. Personally I am a great fan of large-leaved ivies for shady walls. On low walls Euonymus fortune varieties work well. However if you want flowers and a colourful summer display clematis will fit in anywhere. Rather than just planting one, why not grow two together. This will either extend the season or create an exciting colour combination.
Growing 2 clematis together
If you like the idea of something different look out for Actinidia pilosula. This is a deciduous climber, but the twining brown stems are not unattractive in winter. The narrow, pointed dark green leaves are randomly splashed with white as if they have been dipped in a pot of paint. Deep pink flowers hand from the stems in clusters in early summer. This is light enough to fit into a narrow space but has enough character to create an impression.
For shady narrow borders Helleborus x hybridus is a good choice. The dark green leaves on upright stems look good from late spring through fall. The late winter and spring flowers are a delight. I think it is most effective when it is planted as a solo subject all along a narrow border at the base of a wall or fence. If you have an old stone wall and a narrow shady space you will find it hard to choose a better subject.