Sage advice on autumal bloom
For an older generation, the name 'salvia' conjures up the scarlet-red salvia that was once widely used as a summer bedding plant, often along with blue lobelia and white alyssum. Now, it's rarely seen except in some traditional municipal flower beds. The bedding salvia is not hardy and dies with the first frosts.
However, many other kinds of salvia have become available in recent decades. Salvia is part of the very large sage family and offers many decorative species, some of which are hardy summer-flowering perennials, such as Salvia nemorosa and similar kinds, short plants with spikes of small blue flowers.
There are also shrubby forms, such as Salvia greggii, including the two-tone red and white 'Hot Lips', which flowers through most of the growing season. Most of these are native to Central America and can be tipped back by frost but usually re-sprout from the old stems.
The value of salvia continues from summer to late autumn. Salvia confertiflora is a tall, almost shrubby plant with narrow spikes of orange-red flowers. It can be floppy but in a most attractive way. The pink-flowered Salvia involucrata is also a tall perennial with floppy stems, the pink-purple flowers matching well with autumn colours
The friendship sage, Salvia guaranitica 'Amistad' - meaning friendship in Spanish - is a relatively recent addition and has tall spikes of intense violet-purple. The flower spikes are made up of smallish hooded tubular flowers.
These are of typical salvia family shape and are carried at the tops of fairly tall stems from late summer well into autumn and add a great deal to the autumn garden. The intense violet colour offers a strong contrast with the yellow, orange and red of the autumnal foliage.
'Amistad' has related named cultivars of Salvia gauranitica, such as 'Black and Blue', which has strong blue flowers and dark purple-black calyces behind them. 'Blue Enigma' has blue flowers and green calyces which do not offer as strong a contrast. These varieties are not fully hardy, especially in colder areas of the country. The plant forms tuberous roots and grows back in spring from tough stems close to ground level. It's easy to raise cuttings of small shoots taken in summer.
It could also have the root area covered with mulch or coarse sand.
It can grow to over 1m tall and the same width, so it needs space in a mixed border. Pinching out the first young shoots makes the plant more bushy. It likes good soil, fertile and free-draining and should not be wet in winter.
Q I'm going to plant griselinia hedging soon. Have you any general advice for planting - depth, spacing and ground preparation including compost and feeding?
Griselinia is not fully hardy, so does best close to the coast. Plant the young plants 50-60cm apart, in good soil, and in good light. There's no need for feed when planting into good fertile soil, but feed in spring with general fertiliser if growth is slow after a year. Plant to the depth of the soil mark on the stem and keep free of weeds.