Modern container gardening

Isabelle Palmer shares her tips to creating a stylish small space garden

Isabelle Palmer

 

You can grow most plants in containers that you would grow in the open garden. Container plants come in a wide range of shapes, sizes and colours and include small trees (such as purple beech), shrubs (such as pittosporum, phormiums and cordylines), climbers (such as clematis and sweet peas), as well as perennials, grasses, bulbs and annual bedding plants.

To ensure success, ascertain whether you can provide your choice of plants with the right growing conditions. You can easily supply the best growing medium, but the amount of light your outdoor space receives is beyond your control. The level of sunshine is by far the most important factor for ensuring your plants will thrive — some plants like lots of sun, others don’t, so try to choose plants that will grow well in your space. The amount of sunshine a space receives depends on the “aspect”. This is the direction in which your garden faces —whether this is north, south, east or west. This affects which areas get lots of sun and which ones are in the shade for all or part of the day.

Working out the aspect of your space

Using the compass on your smartphone, stand outside with your back to your property and facing your garden, balcony, etc. Whatever position is directly ahead of you is the position your garden faces. So, if south is ahead of you, then your garden is south-facing. South-facing gardens receive the most sunlight; west-facing gardens receive afternoon and evening light; east-facing gardens receive morning light; north-facing gardens receive the least light.

 Sun versus shade – which is better?

Strictly speaking, all aspects have pros and cons in terms of container gardening. Yes, there are more plants that prefer lots of sunshine – and who doesn’t want a sunny garden – but that also means you will have to water your containers more frequently. There are a few tricks you can employ to offset low light levels. For instance, to reflect light back into a space, try painting walls in white or cream, using mirrors and adding pale reflective gravel mulches. These techniques will trick plants into thinking they’re somewhere sunnier. If you’re gardening up high on a balcony or roof garden, then the wind factor also plays a part. Drying winds can desiccate plants, so bear this in mind when making your selection. You can also grow evergreen screening plants such as golden bamboo and laurel in large planters to provide shelter from cold, drying winds for susceptible plants.

Where to start?

I suggest you do a little bit of research and make notes before you buy any plants. This is the best approach for gaining a clearer idea of what you need, so you don’t stand dumbfounded in the garden centre not knowing where to start – which I have done at times.

I advise you to buy your containers first. This may seem a little odd, but it’s the best place to begin. Starting with the containers means that you can decide how much space you want to fill, where to put them and then how many plants you need to get. If you buy the containers before the plants, it’s a good idea to take them with you to the plant nursery or garden centre. If that’s not possible, make sure you at least take a picture of them on your phone. That way, you can match the containers to your selection of plants.

 

Choosing containers

There is a wide range of containers available made from traditional terracotta, concrete and zinc in many different sizes and materials. You can also recycle items to produce a display that’s uniquely yours. Your local garden centre will have a good selection to choose from, and you’ll also find a fantastic choice online. Take the time to consider the sizes, shapes, colours and prices. Putting containers together to create a “garden” is a real opportunity to experiment with different textures and shades.

I think it’s better to buy a couple of key containers than lots of smaller ones. Don’t forget the importance of matching the style/material of the containers to your property. For example, lead-effect planters look great with older properties, modern apartments call for more up-to-date materials, such as zinc, and cottage gardens are enhanced by informal containers, such as terracotta or stone.

 My top tips for choosing containers

  • The bigger the container, the better (this will ensure that watering is needed less frequently and that your plants have room to grow).
  • Deeper pots are better than shallow ones.
  • Ensure containers have at least one drainage hole (three is better).
  • Pick containers that will create focal points.
  • Include containers of different heights and sizes in a scheme.

Container materials

Natural materials, such as terracotta, stone and wood, make the best containers for plants, being more cooling for roots and ensuring plants don’t overheat. You can also buy very good imitation terracotta and stone versions that are just as appealing visually and less expensive. Look for containers made from reconstituted stone and lighter materials such as fibre glass. Lighter containers may be the best option for a balcony or roof garden where weight is a consideration. Wood is also a great choice, but bear in mind that it can rot over time.

Load-bearing considerations

If you only have a balcony or roof garden, it is essential to check with an architect or structural engineer how much weight the space can take before committing to buying containers and plants. If you are planning any major work, such as building raised beds, then also check whether planning permission is required. Make sure you find out whether the balcony is waterproof. Remember, a fully watered container is very heavy, so it’s best to place containers near load-bearing walls, or over a load-bearing beam or joist.

 

 

How to choose healthy plants

Here is a useful checklist of what to look out for: 

Plant health — check for signs of pests and diseases. The eggs of insects, for example, are often attached to the undersides of leaves, so look over the foliage carefully.

Root system — if possible, remove the plant from its plastic pot and inspect the roots. They should be firm and look healthy. A plant that is pot-bound, with a mass of tangled roots growing out of the bottom of the plastic pot, is best avoided.

Leaves and flowers — make sure these look healthy, without any discoloration or markings.

Flowering plants — choose plants that have lots of unopened buds. That way, you know you’ll get great value, particularly from annual bedding plants.

 

Designing container plantings

Putting together wonderful planting displays in containers is both creative and rewarding. From a single specimen in a large planter to miniature “borders” of flowers and foliage in a collection of containers, the opportunities for experimenting with colours, patterns and shapes are endless.

There is a useful phrase to remember when you are designing a container scheme: “Thriller, filler and spiller”. This can be helpful when you’re working out the design for a container and how to compose your plant combinations. For example, if you have a large container, you might want some tall plants at the back to provide height (the “thriller” or focus plant) and then some shorter plants to fill up the middle area of the container (the “filler” plants). To finish the planting, you could choose plants that trail over the sides (the “spiller” plants).

Here is a list of my favourite thrillers, fillers and spillers:

Thrillers Argyranthemum, azalea, campanula, dahlia, delphinium, euphorbia, ferns, fuchsia, grasses, hydrangeas, lavenders, lupins, phormium, pittosporum, sweet peas, tall verbena, veronica

Fillers Anemone, antirrhinum, aquilegia, aster, astrantia, coleus, cosmos, diascia, heuchera, impatiens, pot marigolds, matthiola, osteospermum, poppies, pelargonium, salvia, tiarella, vinca, zinnia

Spillers Calibrachoa, erigeron, ipomoea, lobelia, petunia, trailing ivy, trailing verbena

 

Putting it all together

  • Planting in odd numbers is the most aesthetically pleasing to the eye, so plant one, three or five plants in a container.
  • Consider restricting the colour scheme, opting for shades of one or two complementary colours. This is because too many colours can make a display look too busy and your space smaller – unless, of course, your intention is a cacophony of colour!
  • Remember “Thriller, filler, spiller”: choose a focal plant and complement it with a mixture of upright bedding plants and those that will trail over the sides of the container.
  • Use a focal plant such as evergreen box, lavender or bay to provide year-round interest to which you can ring in the seasonal changes by underplanting with perennials and annuals for summer and bulbs for spring and autumn.
  • Combine plants that have similar growing requirements for the best results. For example, combine plants that prefer full sun or those that require partial or full shade.
  • For small-scale containers, look for dwarf varieties or alpines that will be happier in more confined conditions.
  • Opt for drought-resistant plants such as cacti and succulents, or perhaps sun-loving herbs, if you don’t think you can commit to a daily watering regime for them.

 

Planting mediums

There will be a wide selection of potting mixes on offer at your local garden centre and online. There are two main types of potting mix: soil-based potting mix and soil-less potting mix.

 Soil-based potting mixes

A soil-based potting mix is a reliable, all-purpose mix containing a combination of sterilised loam (soil), peat, sharp sand and fertilisers, making it perfect for most containers. It provides plants with a good supply of nutrients for the weeks immediately after planting and retains moisture well. It is also free-draining, which encourages roots to grow.

Soil-less potting mixes

As the name indicates, this type of potting mix doesn’t contain any loam (soil). Instead, it is usually peat- or peat-substitute-based. If you are concerned about the environmental impact of removing peat from bogs to make peat-based potting mix, then choose one made from a peat substitute such as coir or wood fibre. Soil-less potting mixes are perfectly adequate for most types of plants. They have the advantage of being lighter than soil-based potting mixes, plus they are also often cheaper and ideal for small containers. Their main drawback is that they tend to dry out very quickly and can be very difficult to rehydrate once dry. For this reason, it is a good idea to add some moisture-retaining granules to the potting mix when you plant up your containers. You will also need to feed plants grown in this type of potting mix regularly to keep nutrient levels topped up. I advise against using them for long-term container plantings.

 Taken from Modern Container Gardening: How to Create a Stylish Small-Space Garden Anywhere by Isabelle Palmer, published by Hardie Grant Books, £12.43

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