Consider canna lilies for a bold splash of summer colour
CANNAS or canna lilies are big, bold plants that make a tremendous impact in the garden, both with their large leaves first and then their fiery-coloured flowers.
They have become much more widely grown in recent years as an important feature of the popular tropical planting style, being so vigorous and showy.
But canna does not have to be grown only as part of the tropical-bedding style. It can be grown amid ordinary garden flowers in a bed or border where it will bring contrasting foliage and flashes of colour in late summer and going into autumn. It also looks great grown in a big pot, or pots, and associated with other container plants such as petunias and begonias.
Canna (not to be confused with calla lily which is not related), grows from thick rhizomes, or storage roots, to reach over two metres tall in some cases, though is mostly about 50cm less. Growing that size in a matter of a few months, it is an imposing plant with a central stem or stems, carrying broad paddle-shaped leaves and is topped by a spike of large colourful flowers that open in succession.
The canna came originally from tropical parts of Central America — but it does very well outdoors in our cooler climate, excelling itself in a warm summer and in a warm sheltered, sunny garden. In a cool summer, flowering can be delayed and not as plentiful. It can also be kept under glass.
Given its short growing season, it is a good idea to start off the plants early to make as much growth as possible before planting out after the danger of frost has passed in late May or early June. The roots can be potted up in early to mid-spring and kept in a porch or greenhouse. Early potting means they need attention for a longer period but they get a good head-start on the season.
Pot up in an open mix with plenty of grit or perlite. Keep the growing point near the surface of the compost so that it stays relatively dry and does not rot. Water very lightly, and when the young shoots begin to grow, keep the compost just nicely moist and begin feeding after a few weeks, potting on if necessary. The roots need to be lifted in autumn in cold areas, or mulched well in milder gardens.
While most kinds have light apple-green leaves, there are some dark bronzeleaved varieties (such as ‘Black Knight’ and ‘Tropicana Black’) and striped forms (such as ‘Striata’ and ‘Phasion’) that are very striking. The green forms often have brown markings on the leaves. ‘Wyoming’ is a good orange. ‘The President’ is a strong red, and ‘Lucifer’ is red with a yellow edge, but there are many kinds available.