Over the past few weeks I have shone the spotlight on some underrated but easy shrubs. Before I launch into some more practical posts next week I will first turn my attention to one of the most iconic of all shrubs: the popular and colourful pieris, often simply called forest flame – although this is actually a variety of the Chinese Pieris formosa.
This is a great area for seeing pieris in all their glory and they are a feature of some of the great gardens of Surrey and Sussex. Few shrubs work so hard in the garden. They are evergreen, have lovely ‘lily-of-the-valley’- shaped flowers in large clusters in late spring and the new foliage is usually bright red, being more spectacular than the blooms. The flowers are popular with bees.
There are many variations on this theme and some have pink or red blooms and some have variegated leaves. The flower buds are formed autumn and remain at the tips of the shoots all winter before they open in late spring. Their ultimate height is also highly variable with some exceeding 5m when mature while others are compact, reaching just 1m. So check the labels before you buy.
But all these positive features come at a price. Before you take the plunge and buy a pieris you need to understand what they need to grow well.
1 Principally, they need a lime-free soil. If you can grow camellias and rhododendrons you will be fine. If you have a soil that is alkaline you must grow them in pots and you need to plant them in ericaceous compost.
2 Secondly, they dislike wet, heavy, clay soils. They are best on light, sandy soils, enriched with organic matter. This does not mean that clay should prevent you trying but you should fork in lots of organic matter. If you have access to fallen pine needles make the most of them and dig them in and mulch with them and your pieris will be delighted.
3 Thirdly, a spot in part shade is usually best. If the site is too hot and sunny the foliage will be prone to becoming rather yellow instead of dark green. A spot in deep shade will result in green foliage but you may get a tall and straggly plant and few flowers.
4 And lastly, although the plants are hardy and are rarely damaged by winter cold, the new foliage is very prone to being killed by late spring frosts. This means they should not be planted where they are likely to be affected by late frosts. Overhead branches of trees offer some shade in summer and also light protection from frost and pieris are naturally woodland plants. If planted by a building, one that faces west or even north is better than one facing east. If the plant is small you can cover it with fleece if a sharp frost is forecast in April or May when the new foliage is expanding.
Frost ‘nipping’ the new growth is disappointing but not always a disaster. More new growth usually follows a month later. But you don’t want this to happen every year because it will set the plant back. In my own garden I always seem to get one late frost in spring and my pieris (and Japanese maples) are frequently damaged. My pieris ‘exist’ but they are not happy – as you can see in the photo.
Unlike most of my posts, these photos are not all of plants in my own garden, apart from the one above! But just a few miles away pieris thrive. My garden is new and exposed and as my trees and shrubs provide shelter and shade my pieris will do better!
So if you fancy a pieris, and who wouldn’t, think of where you will plant it. If you have an acid soil and you can grow camellias and your hydrangeas are blue, you can plant in the soil. Even so, make sure the spot is not waterlogged and always dig in plenty of organic matter. A bag of ericaceous compost is ideal but mix it with the soil and do not plant in a pocket of compost.
If your soil is not acidic and your hydrangeas have pink flowers, you will need to grow your pieris in a pot. Use ericaceous compost or Lime-free John Innes compost. If growing in a pot you will need to keep the plant moist at all times and you will need to feed, ideally with a liquid, acid-plant fertiliser every week from April to September.
Whether in the ground or in a pot, the site should be semi-shaded and protected from burning sun in summer and early-morning sun all year. The mature heights of the plants varies so some are suitable for the front of the border and others at the back or at the edge of woodland.
When your pieris is happy it will not need much attention and regular pruning is not needed. If an old plant is overgrown or too tall you can prune it in spring and it will sprout from the base and recover.
What to do this week
Get your mower ready for spring and book it in for a service if necessary
Get ready for sowing. Get your seeds, trays, labels, compost and propagator lids – you can use clear plastic ‘fruit’ containers.
Start summer bulbs into growth in heat indoors including begonias, cannas and dahlias.
Spring talks
Check the details of my talks at Nags Hall and Knights Betchworth if you want to know more about summer bulbs. Tickets must be pre-booked and there are still some left, both with a pre-talk dinner and for the talk alone.
Feed spring bulbs such as daffodils in lawns now by sprinkling some general fertiliser between them. It is more effective to feed now rather than after they have flowered