Features: September 12th, 2014

Patience Atkinson-Gregory has some tips for growing edible plants in containers in community spaces.

Container gardening has become increasingly popular over the past decade, offering more flexibility than fixed beds and displays. Containers can be used to brighten up untidy areas and quirky spaces. This is also one of the reasons that councils and gardening groups use them for Britain in Bloom entries. They have also become an increasingly popular way of growing fruit, vegetables and herbs.

Whilst growing plants in containers is not difficult to do, there are ways of ensuring the best results. Ultimately, the aim is to create ideal growing conditions for whatever you plant. Important areas to consider include:

Drainage – ensure containers have adequate drainage (if not using a self-watering container). Many planters will already have holes in them, but if not, holes should be drilled prior to planting. Self-watering containers are the exception: they don’t have drainage holes because the specialised design means that plants are able to access moisture when needed.

Soil – containers offer the ability to control and vary soil conditions. This is particularly helpful in areas with poor quality soil. Flexibility is also important as plants favour different conditions. For example, lettuce like finely worked soil whilst runner beans will tolerate a coarser texture. The best soil to use is sterilised soil-based compost as plain garden soil tends to be too dense for successful use in containers.

Timing – although containers can be moved and offer some protection from the elements, they are also susceptible to ambient temperatures, which is why our containers have a double walled construction to offer increased insulation. This keeps plants cooler in the summer and warmer in the winter. As a general rule, most seeds germinate best when the soil is warm and the temperature is rising, although this does vary from plant to plant. For example, beans won’t germinate below 5°C whilst lettuce won’t germinate in temperatures above 25°C.

Making the right choice

There are so many styles and sizes of containers on the market, made from such a wide variety of materials that it can often be difficult to choose.

Glazed ceramic and terracotta – an attractive material, but it is prone to cracking when exposed to severe or prolonged frost. Look for frost-proof pots and position them on feet to reduce the risk of frost damage.

Plastic – flexible and hardy material, plastic is a great choice for planters. Difficult to break and lighter and easier to manoeuvre, they don’t dry out as much as clay or terracotta pots.

Wood – rots over time, but treating the wood and lining containers with punctured plastic sheeting can help extend longevity. Half barrels are often used for growing fruit trees. A compromise could be using an ‘Ambarrel’ which looks like wood, but is actually made from recycled polyethylene.

Metal – these containers have become increasingly popular. They don’t crack or rot, but they are susceptible to external temperatures, heating and cooling quickly. They may also rust.

Self-watering – these containers create optimal conditions for growth. Evaporation is kept to a minimum and the roots absorb only what they need. Designed for easy maintenance, each container has a filling point which rarely needs to be topped up more than once a week.

Does size matter?

Containers come in a wide variety of sizes. If aiming to create a dramatic floral impact, large containers work well, whilst smaller containers placed at differing height levels can create an interesting visual impact. In addition, tiered planters are also available on the market to create a cascade and/or tiered effect.
Growing root vegetables such as carrots and parsnips, or legumes and onions, requires larger containers with a deeper base to give the roots room to grow and thrive – a soil depth of around 45cm is ideal. Other edible plants such as lettuce and herbs grow well in planters with a shallower base – as little as 15cm.
Growing edible plants

The list of plants that grow well in containers is long and diverse – these are just a few that are well suited to containers.
Radish – quick and easy to grow, they prefer loose, well-drained soil. Seeds should be sown 2-3cm deep and will germinate in just a few days. They can usually be harvested within 4-5 weeks.
Lettuce – prefer shade in the summer and a well-drained soil. Be careful not to plant them too densely, and watch out for aphid attacks.

Carrots – can be planted from February onwards for June harvesting. As they grow, seedlings should be thinned to around 8cm between plants.

Runner beans – these are thirsty plants so self-watering containers are ideal. A high yielding plant if grown correctly in nutrient rich soil with ample moisture, they are quick climbers and will need canes to grow around; nets can also work well. Intolerant of frost, they should either be started off indoors during colder weather or planted outside once the danger of frost has passed. They also require a sunny location.

Spring onions – easy to grow from seed, these perennial vegetables provide a high yield in minimal space. As they have shallow root systems, they can be grown in small pots as well as with other vegetables. They should be sown around ½ cm deep and apart, in rows 15cm apart, and can be planted throughout the year. They like well-drained soil in a sunny position.
Tip: Try planting a salad garden in one large container, which could include lettuce, spring onions, chives and tomatoes.

Herbs

These culinary staples are particularly well suited to growing in containers. Most prefer a sunny, sheltered position in well-drained soil and may need protecting from frost during colder months.
• Parsley: germinates slowly in warm conditions and requires a rich soil. Prefers partial shade.
• Rosemary: prefers a deeper container in full sun.
• Chives: a perennial herb, these grow slowly, but will tolerate shade. Chive seeds should be sown in the spring under cover in warmth, and then planted outside when they are larger.
• Mint: like chives, mint will tolerate shade and moist soil. Mint can be invasive so growing it in pots can contain it.

As part of their Britain in Bloom entry, community gardening group Blooming Milford in Derbyshire created a herb garden that could be used by all the villagers. Each plant had an information label which explained how they could be used for different recipes and dishes. Planted in large self-watering containers, the herb garden required very little maintenance and was a hit with both judges and villagers. Norwich Council also made herbs a part of their Britain in Bloom entry, with local competitions for schools, residents and businesses to grow herb displays in raised beds or containers.

So, when looking to create displays or to grow edible plants, remember to include containers in your planting scheme – they offer flexibility, variety and the opportunity to create optimal growing conditions.

About the author
Patience Atkinson-Gregory is MD of Amberol (www.amberol.co.uk), a family run company which specialises in horticultural products which are made at the company’s factory in Derbyshire.