Plants For Containers

When preparing garden designs and plans, we are often asked by clients to provide them with ideas and suggestions for plants they can grow in containers – on patios, as features / focal points, flanking walkways or by the front door.

Containers are a good way of making a bold statement, drawing attention to a specific area of the garden, or simply bringing some colour to a patio or seating area.

As with a lot of things, a little careful planning and thought pays dividends when working out what to put in pots.  So let’s take a look first at some plants that are suitable for growing in containers, and then at some more general advice and things to watch out for.

Plants suitable for containers

Some plants to try in pots:

• Annuals and tender perennials
• Herbs
• Clipped evergreens e.g. Box, Yew
• Some medium – large shrubs will tolerate being grown in containers, and this can be a useful way of introducing greenery to a shady courtyard.  Three potential shrubs to consider are Aucuba (spotted Laurel – often seen in containers in cafes in France and Italy – ), Viburnum tinus and Prunus lusitanica.  Often these plants are clipped for a more formal and neater effect.
• In areas with alkaline soils, containers with ericaceous compost (compost which is lime-free and more acidic than most) may be the only way of growing plants such as Camellias, Pieris and Rhododendron.  See note on maintaining acidity of soil below.
• Small evergreen shrubs such as Pittosporum ‘Tom Thumb’, Euonymus ‘Emerald and Gold’ (and ‘Emerald Gaiety), Skimmia japonica ‘Rubella’ (and others), Photinia ‘Little Red Robin’.  Also Lavender and Hebe.
• Grasses e.g. Festuca glauca, Pennistum
• Smaller conifers e.g. Juniperus squamata ‘ Blue Star’.  Also some Thuja.
• Evergreen perennials such as Heuchera and Bergenia.  Also herbaceous perennials with attractive foliage e.g. Hostas (see note on slug control below)
• Long flowering small deciduous shrubs e.g. hardy Fuchsias
• Smaller climbers e.g. some Clematis and Ivies
• Exotic flowering plants e.g. Agapanthus, Lilies (which benefit from the good drainage that containers can provide)
• Spikey plants e.g. Cordyline and Yucca (but beware the razor sharp leaf edges of many Yuccas)
• Ferns e.g. Asplenium and Polystichum – great in shade

The RHS website is a good place for more detailed plant information (type the plant name into their search box).  If you’ re looking for images and inspiration, try typing in any of the names above (combined with the word ‘container’ and/or ‘pot’) into the Google image search.  It’s obviously not a technical reference point, but is usually a good way to quickly find an image.

Container Arrangements

When planning what to grow in containers, gardeners often think about which plants to combine in a single pot, but it can be more effective to grow plants in individual containers, and then to arrange the containers to provide attractive combinations of foliage size, colour and texture, as well of course as flower colour.  If you’re not confident in arranging your containers, one tip is to make sure that there is some thread of commonality running through your arrangement – that could be the  type and/or shape of the containers as well as the type/colour of the plants.

If you do want to combine more than one plant in a single pot, a few tips:

• Firstly, check that the container is big enough – see below.  Less important for annual arrangements, but when it comes to perennials, remember they will grow!
• Consider the overall look you are aiming for – a mass of flowers and colour, or perhaps a more structured, ‘tidy’ arrangement
• Linked to the above, think about form.  Consider having a taller, structured plant in the centre, surrounded by a mixture of shorter and/or trailing plants (the latter are useful if the pot is not particularly decorative!)
• Within reason, only group plants that like the same sort of soil/sunlight levels/watering

Size

When thinking about what to plant in a container, it is important to remember that no plant likes to live in the same (or indeed any) pot forever.  As the plant grows it will quickly consume all the nutrients in the soil, and its roots will outgrow the allotted space.

So, while the plants are young, they will need repotting into larger pots with new compost periodically, and also feeding during the growing season.

With larger plants, there will almost inevitably come a time when it is no longer practical to keep potting up an ever larger plant.  Here, it is important to try to remove the top few inches of soil / compost each year and to replace this with some fresh new compost.  The plants will also benefit hugely from being fed.  Ideally, these large plants will eventually be found a home in the flower border, but if not they may continue to flourish in their pots until they finally get pot bound and begin to look less healthy.

Pests & Other Problems

Pests such as vine weevil and red spider mite can be a problem when growing plants in containers, and some form of chemical or biological control might be necessary.  Vine weevil, for example, are very fond of plants such as Heuchera and Fuchsias.

For plants that need lime-free, acidic soil, over time, watering will cause ericaceous compost/soil to become more alkaline.  To compensate, boost the soil periodically with iron sequestrine.

Some plants are particularly liable to attack by slugs and/or snails – Hostas (see photo to right) for example.  Damage can be restricted by mulching the soil with a coarse grit, and also standing the pot on a layer of grit.  A band of copper around the edge of the pot can also be effective.

And a final tip – you can often buy summer flowering perennials inexpensively by buying them in small 9cm containers, and many garden centres will also give volume discount if you buy say 5 or more.  Try growing these in their first year in a few pots on the patio to give you lots of summer colour, and then planting them out in the autumn!

Image credits: ALDA, Morgaine