When autumn rolls around in Wairarapa after a dry summer, the flower garden is not in the best of health.
Even dahlias, which have been providing flowers for ages, seem to wilt under heat and dryness, their foliage falling victim to mildew. This is especially noticeable on dark foliage varieties.
Fortunately, there are some plants that thrive under these conditions. One of my favourites is the light blue flowered plumbago. This is an almost-hardy scrambling shrub that does best in hot and dry areas. We have one planted underneath a small Euonymus tree, in very dry conditions. It scrambles out from the bed and onto the edge of the lawn to capture more light, which is great as it gives a lovely light blue edge to the border.
This year, it has higher goals. Walking past the tree, I noticed that the plumbago had slithered its way up through the branches and was flowering at about three metres. It was a bit of a surprise, but charming to see the pretty flowers looking as though they were part of the tree.
There is another pretty autumn flowering plant, much smaller growing, but also having gloriously deeper blue flowers. Commonly called Chinese plumbago to botanists, it has the slightly unwieldly name of Ceratostigma willotianum. It is a small deciduous shrub, growing to maybe a metre or so high, with a similar spread. It has green leaves that contrast nicely with the darker stems and branches.
But it is the cobalt-blue flowers that are the main attraction. They are carried at the end of the branches and attract both bees and butterflies. I think it is a great plant for the edge of a garden bed or for popping into a mixed perennial border.
The crepe myrtle is another plant that comes into its own at the time of the year. It is a large shrub or small tree with the impressive name of Lagerstroemia indica. It is upright, growing with leaves that open bronze but quickly become dark green. The flowers are deeply crinkled [which leads to the “crepe” part of the common name] and come in an interesting range of colours.
They are deciduous so that may explain why they are not more popular, but they are lovely garden plants, mainly growing to about 2.5 metres high. They are very trainable and respond well to a little judicious pruning. They prefer an open, well-drained position and should cope with any frosts that Wairarapa may throw at them.
Among the better varieties is ‘Bergerac’, a tidy growing variety with deep pink flowers. ‘Soire D’ete’ has much lighter pink flowers, while “D Puard” has flowers that are bridal pink. There are white varieties around – ‘Townhouse’ is popular, as is ‘Kimono’ – as well as much darker forms like the purple ‘Tango’
If you are a little constrained for space, you could try ‘Samba’, which will only grow to about 60cm high, so it is ideal in a pot or on a patio.
The star of our autumn garden is undoubtedly the royal purple flowered salvia called ‘Amistad’. This is a very popular variety, partly because of the strongly coloured flowers, held in typical salvia fashion and popping out of nearly-black calyxes. The other reason it is so popular is its extended flowering period. It starts in early summer. Then has a moderate display over the warmer months and an eye-popping crescendo in autumn.
It does best in full sun and prefers well-drained soil, but it can withstand dry periods very well. It is said to be a little frost-tender, but our plant is over 10 years old and has survived all those winters. The books say it will grow to about 1.5 metres, but ours tops out at over two metres.
There is a plethora of autumn flowering salvias. We grow a relative of ‘Amistad’ called ‘Black and Blue’, which is a little more restrained in terms of height. It has the same black calyxes, and the flowers are cobalt blue.
My mother used to grow the slightly wild-looking Salvia uliginosa. This has bright sky-blue flowers carried atop tall stems and will flower right through the summer and into the autumn. It is commonly called the Bog Sage, which is an indication that it will cope with heavier and moister soils than most of its relatives.
If blue is your colour, there is a strikingly coloured form to keep an eye out for – ‘Blue Angel’. This is a variety of the gentian sage, S. patens, and has masses of gentian blue tubular flowers through summer and into autumn. It will not stand heavy frosts but should be fine in Wairarapa. It has the odd habit of dying back each winter to tuberous roots, which quickly spring back into growth with the new season.
