There is hardly a more fail safe choice for summer pots and baskets than petunias. Striped, starred, multi-toned or plain, they come in almost every thinkable colour, combining graceful beauty with astounding toughness.
Petunias are renowned for their ability to prevail through the hottest months of the year and, unlike varieties of old, today's petunias stand up to wet weather too. Their vampy trumpet flowers are produced in astounding volume in a non-stop display from spring till the first frosts of winter. The sooner you plant them, the longer you’ll enjoy their startling effects.
Plants are available as seedlings in punnets or advanced ‘potted colour’ seedlings in bloom, to larger multi-branching plants that will quickly fill a large pot or basket, one plant often doing the job of up to ten seedling plants.
The more sun they see, the more flowers petunias will deliver. Although drought tolerant, they’ll give their best performance with regular summer watering, especially when grown in hanging baskets. Well-drained potting mix is essential. Use slow release fertiliser at planting time with extra liquid feeding up to three times during the season. Most modern strains drop their flowers cleanly and generally don’t require dead-heading, but occasional light trimming keeps plants looking tidy and encourages further flowering.
Close petunia cousins, the Calibrachoas are for all intents and purposes mini-flowered petunias. Just a few centimetres in diameter, their flowers are produced in teeming hundreds to completely smother strong spreading plants with attractive small leaves. Like petunias, calibrachoas are long flowering, sun loving and highly weather tolerant.
A fantastic option for shadier parts of the garden, a hydrangea in bloom sits beautifully in a large pot (350-500mm wide). Any hydrangea can be grown successfully in a pot, but the compact growing varieties, such as Tuxedo, are ideal.
A good sized pot and attention to watering is important to prevent drying out. Adaptable to sun or shade, hydrangeas prefer a spot that receives morning sun and afternoon shade, although too much shade limits flowering. For best flowering, feed regularly over spring and summer.Some hydrangeas change colour according to the soil pH. For pinker flowers, increase the soil pH by adding lime; for bluer flowers, lower the soil pH by applying aluminium sulphate. White varieties are not affected by soil pH but feeding with sulphate of potash a few times a year will help maintain a true white colour.
Pruning once a year after flowering (in autumn, winter or early spring) maintains good shape and flowering. Cut stems to just above a pair of fat swollen buds (these are the ones that deliver next season's flowers). Ideally, hydrangeas are pruned to about half their height, but those in deep shade (or overgrown ones) will produce flower buds higher on their stems. Hardwood cuttings taken in winter will propagate easily.
Pelargoniums (also confusingly known by the common name ‘geranium’) have a long history as unwavering stalwarts for colourful summer containers. They are famously ‘Mediterranean’ and renowned for their tolerance of heat and drought. Cascading ivy-leafed pelargoniums look great in hanging baskets and window boxes and will often be seen climbing up a power pole. Bushy upright forms include the pot-perfect ‘Ringo geraniums’ available on seedling stands and the likes of the Pac pelargonium sold as larger advanced plants ready to enjoy in an enticing array of colours. Choose snowy white, classic red or one of many beautiful shades of pink, orange and lilac.
Another group of pelargoniums to explore are those grown, not so much for their dainty flowers, but for their highly scented leaves. They are especially valuable plants for the sight-impaired. Scents include peppermint, spicy, rose and citronella to ward off mosquitoes.
Impatiens have long been a top choice for colouring shadier parts of the garden, and in recent times breeders have come up with varieties like ‘Sunpatiens’ that will also thrive in full sun. They are fantastic for all kinds of containers, and very good in the company of ferns and fuchsias. Available both in seedling punnets and as larger instant landscape plants, modern impatiens are compact and free flowering in a wide choice of vibrant colours. Larger flowered New Guinea hybrids have equally exotic foliage and provide an instant touch of the tropics.
Eye-catching and easy-to-grow mandevillas are twining plants with dark glossy foliage and masses of flashy trumpet flowers in shades of red, pink and white. Their easy-care nature and amazing heat and drought tolerance make them perfect for pots as evidenced by their ubiquitous presence around the cafes and tourist traps of Europe.
These heat loving plants hail from Brazil. In frost free climates they are long living evergreens which will climb 3 to 4m on a support. Or simply snip off the growing tips for a bushier growth habit. Where winters are cold, they’re grown as annuals - enjoyed for their constant and prolific flowering from spring till first frost. New hybrids have been developed with more compact and shrubby shapes.
Mandevillas enjoy full sun or part shade. Water deeply, once or twice a week, depending on weather conditions, allowing to dry out slightly in between waterings. Mandevillas hate wet feet, so avoid overwatering. Support constant flowering with liquid feeding once a fortnight. A light trim after flowering will promote new growth and enhance flowering performance. Wear gloves when pruning to protect your skin from the milky sap.
Simple, sun-loving daisies provide generous colour though summer and autumn, offering lots of options for pots. The compact marguerite daisies (Argyranthemum) with attractive fern-like foliage come in a lollie scramble of colours and flower forms. Favourites for pots include the Federation Daisies.
Osteospermum, Gazanias and Arctotis are the African daisies with a huge array of modern compact varieties in spectacular colours. In coldest climates these frost tender beauties are grown mainly as annuals. Echinaceas (aka coneflowers) bloom from summer through autumn with modern pot-friendly varieties offering an exciting range of colours.
A beautiful option in sky blue, Felicia is another strong contender for a good sized pot. Brachyscome (aka Swan River daisies) have fine ferny foliage and lashings of dainty daisies in pink, white or lavender blue. And let’s not forget Gerberas; no longer the tricky to grow cut flowers of yesteryear. Excellent compact Gerberas varieties for pots are now widely available in garden centres.
Choose top quality container mix for optimum drainage with best possible water holding capacity. Most contain controlled release fertiliser to get plants off to a healthy start. Some also contain a wetting agent which helps to spread the moisture throughout the potting mix. Otherwise you can add this yourself.
In summer, daily watering is the necessary norm for plants in pots. In very hot dry weather you may need to water twice a day,especially when it’s windy. Windy weather accelerates water loss through leaf and pot surfaces, so avoid windy locations if possible, especially for hanging baskets.
Feed little and often with liquid fertiliser or add controlled-release fertiliser. Plants in pots need more frequent feeding than those growing in garden soil.
