The Newnham Naturalists – gardening with annuals

annual borders in front of Kennedy

By far the most photographed bit of the garden at the moment seems to be the annual borders in front of Kennedy.  In the middle of July, they are probably at their peak, but with rigorous weekly dead- heading (please feel free to dead head as you walk past!), they should be flowering well into October and the first frosts.

Often when people think of annuals, they think of the bedding displays on roundabouts and in parks – regimented flat lines of marigolds and lobelia, or clashing pelargoniums. But because annual plants cram all their energy in to one season, you can, with a good seed catalogue and some space to pot on seedlings,  create a truly spectacular  display that will provide colour and cut flowers for the whole summer. And at the end of the summer, if you leave some seed heads to ripen, you can collect seed to have free plants next year.

By choosing a selection of different annuals, and spreading the sowing over several weeks, it is possible to achieve a succession of plants, with some flowering best early on before the later species take over. In the beds here, the white Clarkia dominated in June, now replaced by the yellow Calendula as the main front border plant. Every year I try growing a couple of varieties that I haven’t tried before, to see how they grow and how well they perform – my favourites  this year  are the annual Delphinium Blue Spire, and the Salvia horminum Oxford Blue, both of which have been flowering well for a month now. But there are some reliable easy annuals that I grow every year so that if all else fails, the flower beds will still be full, and here are my top five:

  • Cosmos – there are hundreds of varieties available in lots of different sizes and colours, but I always grow the large white ‘Purity’, because it is so reliable and looks good with everything
  • Tithonia rotundifolia – also known as the Mexican Sunflower, the bright orange of the flowers is fabulous, and works very well with dark leaved Dahlias
  • Cleome spinosa – available in various shades of white, pink and purple, they flower well all summer with very little work, with the new flowers appearing at the top of the stems above the seed pods
  • Nicotiana – many species and varieties, all worth trying for a range of colours and heights. My  favourite is Nicotiana sylvestris, which looks tropical with its candelabras  of fragrant drooping white flowers suspended above enormous leaves
  • Ipomoea – there are lots of splendid annual climbers, great for adding height to the border so it is difficult to choose just one, but Ipomoea tricolor  Heavenly Blue really is divine, and for something  interesting, try Ipomoea lobata with flowers that change from cream, through yellow orange and red up the spikes.

In fact, not all of the plants in the borders at Kennedy are strictly speaking annuals. There are four different salvias, only one of which (Salvia horminum Oxford Blue) is an annual. We do the two large herbaceous salvias, Amistad and Phyllis’ Fancy, from cuttings, and over-winter them in a warm greenhouse. The small blue-flowered one is a microphylla–type, and hardy, so will be planted out in other beds when we change the display in the autumn.

Gardening with annuals seems to have become rather unfashionable, but even if you don’t have the room for a whole border devoted to annuals, it is well worth growing a few to fill gaps in your herbaceous borders, as we have done in the borders in front of Peile. Anyone with large oriental poppies will know about the equally large unsightly holes left when they have gone over. A couple of Cosmos or Cleome, planted out just as the poppies are going over will fill up this hole, and flower for the rest of the summer.

Lottie Collis
Head Gardener

Moth of the month:  Elephant Hawk-moth, Deilephila elpenor  

This is probably the most glamorous moth we’ve had this month. A fetching combination of khaki green and shocking pink with a few splashes of white, and a wingspan of 70mm, make this a very welcome visitor to the moth trap. Surprisingly common, a night’s catch can include six or more of these colourful beasts, but one or two is more likely.

They are on the wing in June and early July, feeding mainly at night on the nectar of honeysuckles, petunias etc, hovering in front of the flowers and lapping the nectar with long tongues. Their larvae are said to resemble elephant trunks, hence the name, and feed on Rosebay Willowherb and Bedstraw.

  • Gardener Chris Thurgood is our ‘moth man’. His keen interest in Lepidoptera (which means “scaly winged”) aka…moth watching, extends to operating a moth trap in Newnham gardens.  This is basically a wooden box with an ultra-violet light on top that attracts and holds the moths until morning, when they are identified, counted and then released.