Put aside your prejudices when you hear the name and embrace this easy annual.
Some plants get left behind in the race for more compact, more colourful and more exciting varieties. And some plants, though excellent in the garden, do not look good when young. This is a serious disadvantage in this age of instant gratification when we want to buy petunias in bloom and even wallflowers with buds in autumn.
Convolvulus tricolor is one such plant. If you want to grow it you need to sow seeds. I have never seen plants for sale. Despite the huge sales of cosmos in two litre pots in August, it is not the most sensible thing to do to buy large pots of annuals. Now in the garden, convolvulus is an ever-increasing mound of sinuous, Medusa-like stems. From every leaf axil grows a long pedicel carrying one beautiful, funnel-shaped flower, carefully positioned to face the sun. The trouble is that plants don’t bloom when tiny and, in pots, the mass of entangled stems would make the garden centre sales bench look like a tossed salad once customers got their hands on them. Commercially they are a disaster.
Forget the unavoidable visions of bindweed. For a start bindweed is not botanically convolvulus, it is Calystegia. Convolvulus are much better behaved and the best known is the Mediterranean shrub C. cneorum with silver leaves and white flowers. The more adventurous may know the creeping, blue C. sabatius and the seductive, satin pink, but potentially invasive C. altheiodes.
But I digress. Convolvulus tricolor has flowers with, your guessed it, three colours; blue, white and a yellow centre. Usually only available as a mix of two shades of blue, pink and white, the deep blue ‘Royal Ensign’ and ‘Blue Flash are sometimes available. The pinks are usually shaded with intense eye markings reminiscent of the fanciest, modern hemerocallis. Despite the clarity in the blue flowers I find the pinks strangely appealing. All are neat and pretty and, unlike so many annuals the plants remain in bloom for a very long time. They have no value for cutting unless you like replacing your vase every few days.
The seeds are large – peppercorn size – so very easy to space out and sow. The seedlings are large too and grow vigorously. I do sow these in cells too and sow two seeds per cell. Even better, the large seeds are easy to collect so you don’t need to buy them every year. I find these are best sown in spring as they do not survive winter well and I have not known them to self seed much – in fact not at all – but they may do so in milder climates and lighter soils. When well grown the plants will reach 40cm tall and at least as much wide. They are good plants to pop into gaps in the herbaceous border and would be ideal for mixing with hardy geraniums for later colour and to plant over daffodils to hide their dying foliage. Or plant with lupins to fill the gap they leave after flowering.
South Africa is the home of many of our summer flowers but this is another Mediterranean plant.