The sage family is a rich source of good garden plants. Sage is used as a cooking herb, but many other related plants are grown for their decorative value, usually under their botanical name of salvia. The best-known is probably the red salvia used as a summer bedding plant. It is not hardy and dies with the first frosts.

Salvia nemorosa and similar kinds are very popular for early summer. Shrubby forms, such as Salvia greggii, especially the recently launched ‘Hot Lips’, offer great value from spring to autumn. Even in winter, these can have a few small flowers.

In autumn, there are several good kinds. Salvia confertiflora is a tall, almost shrubby, kind that has narrow spikes of orange red flowers. Although it is a bit ungainly, it is a most impressive plant in flower.

Also given to producing long, lanky stems is Salvia involucrata, each one topped with a spike of neon-pink flowers, a wonderful sight in autumn. Added to that illustrious list more recently is the ‘friendship sage’, Salvia guaranitica ‘Amistad’. Amistad is the Spanish word for friendship, hence friendship sage. It is a great name, easy to recall, and has no doubt helped in making this plant better known.

But ‘Amistad’ has not yet found its way into many gardens, though everybody who sees it is impressed, and it will gain greater popularity in future. This plant has tall spikes of intense violet-purple. The flower spikes are made up of a series of hooded flowers a few centimetres long. These are of typical salvia family shape and are carried at the tops of fairly tall stems from late summer well into autumn, and it was still in full flower in November this year. The long, warm autumn obviously suited it and it might not have lasted as well had harsh weather come earlier.

But it is a flower for the late season and it adds a great deal to the autumn garden. The intense violet colour offers a strong contrast with the yellow, orange and red of the autumn colours of trees and shrubs, the sage highlighting the lighter colours. Just a touch of intense violet is enough to have this effect, so even a single plant can do the job.

It shares this contrasting function with Aconitum carmichaelii ‘Arendsii’, which is deep blue, and the deep blue-purple flowers of strobilanthes. Although too much of these dark colours could be deadening.

‘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. ‘Purple Splendour’ has purple flowers.

The original species is from South America and not fully hardy, especially in colder areas of the country. It forms tuberous roots and comes back in spring from tough stems close to ground level.

It is easy to raise cuttings of small shoots taken in summer, and this is a way to protect against losses in winter. It could also have the root area covered with mulch or coarse sand.

The plants can grow quite large to over 1m tall and at least the same in width, so it needs space in a mixed border and suits rural gardens very well.

Some brightly coloured pink or orange dahlias nearby can be very striking. These salvias like good soil, fertile and free-draining and should not be wet in winter. CL

Last-ditch nasturtiums

Nasturtiums are great indicators of the first really hard frost. No plant melts under frost in quite the same way as nasturtiums do. The leaves and stems collapse onto the ground, turned to slush in one night, almost like wax too close to a flame. Though gone in some places, they hang on in others, sometimes in the same garden. Nasturtiums have been remarkably good this year, growing strongly and flowering into late autumn. But they are on borrowed time.

Soon all the tops will be gone and only the seeds remain. The seeds are large and resistant to frost because of the corky layer wrapped around them. This acts as insulation against the cold. When the seeds form first, they are green and later turn light brown, as the corky layer forms. Many seeds survive the winter frosts and germinate in late spring or early summer. So well does this strategy work that it is usually only necessary to sow the seeds once and, for many years, self-sown plants reliably appear!

This week in the garden

Flowers

Bulb planting must be finished off as soon as possible. Tulips can be planted into November, but it is best to plant early. If the soil is not wet, perennial flowers can be lifted and divided or new kinds planted. Gladiolus and dahlias may need to be covered with sand or soil or lifted. Pots, baskets and flower beds can still be planted up.

Trees, shrubs and roses

The traditional deciduous bare-root planting season has begun. Evergreens can still be planted, but it would be best to wait until spring in an exposed site, where winter winds might dry out the foliage. Rose bushes can be planted now. Check the tree ties on trees planted and staked in recent years to ensure the stakes are solid.

Lawn

Grass growth has slowed, although lawns are generally in good condition, after a remarkable summer of growth. If lawn moss is obvious, apply sulphate of iron. Repairs to a damaged lawn can be carried out and humps and hollows fixed. Seed will be slow to germinate now, but it can still be sown in good weather.

Fruit, vegetables and herbs

The vegetable area can be tidied up, and perhaps dug over, but weeds should certainly be controlled now. Plant fruit trees and bushes. Most fruits are very easy to grow, but they must have a good site, some shelter and good deep soil for best results. Established fruit trees can be pruned, with the exception of plum trees.

Greenhouse and house plants

Check for pests, such as greenflies, that can cause a lot of damage now. Remove all plant debris and dead plants. Pots and trays can be washed and the glass cleaned to improve light levels. Tidy away old tomato plants. Water house plants very little and do not stand the pots in saucers of water.