Forgotten silver

Sunday, 01 June 2014

Agave americana

I have been thinking about silver-leaved plants a lot this week, having spent time going round the garden with a visitor interested in growing some of these plants; and also having contemplated the value of silver foliage plants in inland country gardens with cold winters and hot, dry summers. I have previously written two blogs about silver leaves: one focused on those plants which light up shaded spots, and the other looked at those that cope well in hot, sunny positions. Glancing over these blogs, I realised I had left out a few plants, so this week I am going to talk about these.

Tradescantia zebrina with button fern

For shade, one of my favourite silver plants is Tradescantia zebrina (ht 20 cm), with its striped leaves of silver and olive green. I have to admit that yes, indeed, it is a relative of that horrid weed wandering jew, but though it is very easy to grow, I have never regarded it as a menace. I wouldn't put it in rich, moist soil in a prize position - where it would surely swamp everything in sight - but used in a shady, dry border where little else will grow, it forms a lush carpet and brightens up dark corners. I just pull up handfuls of it when it has wandered too far. I grow it near the so-called button fern (Pellaea rotundifolia, with very dark green, rounded foliage. This Tradescantia also looks superb in a hanging basket if you prefer to constrain it.

Justicia scheidweileri growing in the Royal Botanic Garden, Sydney

A diminutive plant for shade that comes from the Acanthaceae family is another tough one for dry spots. Justicia scheidweileri (ht 20 cm) has elongated, silver-marked leaves and pretty burgundy and mauve flowers over a long period. It self-seeds gently but new seedlings are always welcome and are a pretty contrast to the pure silver leaves of Plectranthus argentatus or rhizomatous Begonia cultivars. It too can be used as a basket plant.

A miniature form of Ctenanthe, name unknown

Ctenanthe setosa has some silvery forms, including 'Grey Star' (ht 1.2 m), which has large, oblong leaves with green veins. I also have a miniature form, which has grown no higher than 15 cm and is forming quite a good groundcover. I haven't been able to find out its name yet. I have it growing with ferns - some all-green and others silver-marked.

Shrub Begonia Little Brother Montgomery

Some shade-loving shrubby and cane Begonia have silver spots or markings but the most ornate is possibly the shrubby cultivar 'Little Brother Montgomery', which has showy star-shaped leaves with dark centres. It pairs well with dark purple foliage. It also has pretty pink flowers! It grows well in a pot.

Salvia fruticosa

Many silver plants do well in hot, dry spots as their silvery colouration is an adaption to these conditions. A fairly recent addition to my Salvia collection is Salvia fruticosa, sometimes marketed as Salvia 'Greek Skies'. This is a shrubby plant to about 60 cm tall, with attractive sky-blue flowers in spring. It copes with drought and frost once established. Its leaves look and smell like the culinary sage (Salvia officinalis, but I haven't dared to eat it so far. Another tough silvery plant I grow is Agave americana (ht 1.8 m, pictured at the start of the blog), a succulent plant from Mexico with stemless rosettes of thick silvery-grey leaves that have very sharp spines. The plant needs full sun and good drainage - it is quite drought tolerant but doesn't like frost. It can be grown in a large pot.

Buddleja Silver Anniversary

The genus Buddleja has several silvery-leaved cultivars. 'Lochinch' (ht 2.5 m) is my favourite of these, with its soft lilac blooms in several flushes from late spring through to autumn. I also like 'Silver Anniversary', a smaller shrub (ht 1.5 m) with slimmer silver leaves that have a velvety texture, and small clusters of scented white flowers.

So silver plants can fill some of those 'difficult' spots that every garden has: from dry and shady to hot and sunny. I've probably forgotten lots more - they will have to wait until another time.