Paeonia clusii

April flowers to plant

Fresh, white flowers and arresting foliage feature among Keith’s choices this month along with a hybrid form of one of his favourite plants. Photographs Jason Ingram

April sees spring swing into bloom. Here’s plantsman Keith Wiley‘s choices of the best flowers to plant this month. For Keith’s monthly column, subscribe to Gardens Illustrated magazine. 

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Tulipa 'Peppermint Stick'
© Jason Ingram

1

Clematis ‘Lunar lass’

Clematis 'Lunar Lass'
© Jason Ingram

An evergreen clematis scrambling to only about 60cm in height but covering itself in scented flowers in the spring. As with many of these New Zealand hybrids the leaves look tough and leathery but the plants actually need a sheltered spot and are usually considered to be conservatory plants, or grown as patio plants brought in
for the winter. I grow mine in a very well-drained raised bed under cover but open on all sides where it scrambles through low-growing daphnes. Height 60cm. Origin New Zealand. Conditions Well-drained soil in a sheltered site, ideally south- or west-facing; full sun. Hardiness RHS H2, USDA 7a-9b. Season of interest Late winter and spring for flowers.

2

Epimedium grandiflorum ‘Nanum’

Epimedium grandiflorum 'Nanum'
© Jason Ingram

One of the smallest, if not the smallest,  of epimediums, reaching only 15cm in height when in flower, with a later flush of leaves growing a little higher. The combination of a dome of dapper leaflets each margined with a border of purple red, beneath sprays of large, pure-white flowers opening from pink-flushed stems and buds, is a jewel-like joy of spring. Not surprisingly such beauty bears close scrutiny so this plant looks especially good when potted and placed at eye level. Height 20cm. Origin Japan. Conditions Open, well-drained soil; shade to part shade. Hardiness RHS H5, USDA 4a-8b. Season of interest Spring mainly, summer foliage.

3

Adiantum pedatum ‘Japonicum’

Adiantum aleuticum 'Japonicum'
© Jason Ingram

A hardy maidenhair fern with the most amazing burnished copper-coloured young foliage. This colouration gradually fades to green over a period
of three to four weeks. In the best forms, which are worth seeking out, it unfurls its croziers a really rich colour but this can vary in its intensity from season to season, depending perhaps on weather conditions or light levels. Makes a lovely clump of foliage throughout the summer and is one of my favourite smaller ferns. Height 45cm. Origin Japan. Conditions Best in a good woodland soil; part shade. Hardiness RHS H5, USDA 6a-8b. Season of interest Best in spring, but still good in summer.


4

Magnolia laevifolia ‘Gail’s Favourite’

Magnolia laevifolia 'Gail's Favourite'
© Jason Ingram

This evergreen species, previously known as Michelia yunnanensis, has always been described as only suitable for the very mildest climates. With me it has survived virtually unscathed in the open garden for the past ten years. Raised in New Zealand, this cultivar is one of the best selections, with flower buds and young growth covered in rich golden-brown indumentum that persists on the undersides of the leaves. The scented flowers are produced later than most of the deciduous magnolias. Height 2-3m. Origin Garden origin from New Zealand (species from Yunnan). Conditions Acidic soil; full sun, sheltered from strong winds. Hardiness RHS H4. Season of interest Spring for flowers.

5

Paeonia clusii

Paeonia clusii
© Jason Ingram

A species herbaceous peony with class stamped all over it. A relatively low-growing plant with dissected leaves and pristine white, large, scented flowers of beautiful form, flowering for several weeks. In the wild it grows at high altitudes in Crete, so is temperature hardy in the UK, but as it comes into growth very early it is vulnerable to spring frosts. It also prefers well-drained conditions so I grow it in a stony raised bed in an open-sided airy polytunnel where it gets better every year. Height 40-50cm. Origin Crete. Conditions Well-drained soil; sheltered, sunny site. Hardiness RHS H3 (because of early growth). Season of interest Spring for flowers; spring and summer for foliage.

6

Uvularia sessilifolia ‘Variegata’

Uvularia caroliniana variegata
© Jason Ingram

A rare woodlander that should be better known. It forms a gently spreading clump of attractive leaves narrowly edged in cream, which gives the plant a creamy-grey appearance that contrasts well with the dark stems and pendent cream flowers. This does spread but not frighteningly so, and only reaching a height of about 30cm, it is delicate and refined enough to coexist peacefully with many other woodlanders, such as trilliums and erthroniums, unlike the similar but distinctly more thuggish and larger, Disporum sessile ‘Variegatum’, which will quickly swamp its neighbours. Height 30-40cm. Origin Canada and USA. Conditions Woodlander for part shade. Hardiness RHS H5, USDA 5a-9b. Season of interest Spring and summer.

7

Acer palmatum ‘Corallinum’

Acer palmatum 'Corallinum'
© Jason Ingram

Japanese maples are such good year-round plants. Nearly all have graceful winter form with the delicate tracery of their naked branches and are renowned for their autumn colour, but it is for the spring colour of the new foliage that I value them. For this there is none more spectacular than ‘Corallinum’, which for nearly six weeks literally puts even the massed flowering of the evergreen azaleas in the shade. Sadly, there is no autumn colour worth mentioning. AGM. Height 2m. Origin Garden, bred at Hillier’s Nursery, in 1910 (species Japan). Conditions Well-drained soil; full sun to part shade. Hardiness RHS H6, USDA 5b-9b. Season of interest Spring to early summer for rich colour.

8

Erythronium ‘Joanna’

Erythronium ‘Joanna’
© Jason Ingram

April is the main erythronium flowering month in the UK. If you want your erythronium to produce a good clump of flowers, I’d recommend one of the hybrids and ‘Joanna’ is a really good choice. It is a cross between a pink-flowered species and a yellow one that serendipity has managed to merge into a winning combination that borders on apricot in colour, while maintaining a species charm in the flower form. Robust in growth and very free-flowering, it is an excellent erythronium for general planting. Height 40cm in flower. Origin Garden origin. An Erythronium revolutum x Erythronium tuolumnense cross bred by John Amand and named for his daughter (species North America). Conditions Fertile soil in part shade Hardiness RHS H4, USDA 5a-9b. Season of interest Spring.

9

Iris ‘Mrs Nate Rudolph’

Iris 'Mrs Nate Rudolph'
© Jason Ingram

To be honest, I’m a little ambiguous when it comes to these dwarf bearded iris cultivars. When they’re in flower I adore them, but then my passion starts to wain as the season goes on and their foliage becomes just that little bit tatty. I’m sure this says more about my inability to use them correctly and in the future I do have plans to be a little more sympathetic to their growth patterns when choosing where I grow them. However, in the meantime I will just have to luxuriate in their colours and the classic simplicity of their flower form. You will, however, need to watch out for slugs that will damage flowers. Height 15-20cm. Origin Garden origin. Conditions Well-drained soil; sunny spot. Hardiness RHS H6, USDA 3a-8b. Season of interest Spring.

10

Rhododendron augustinii ‘Lanarth Green Eye’

Rhododendron augustinii Green Eye Form
© Jason Ingram
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As this is a species that flowers in April, it is one that is vulnerable to spring frosts although it will tolerate a degree or two of frost without flower damage. If you have the space to accomodate it then it really is one of the glories of the woodland garden. It’s a species that can vary widely in colour from pale purple to rose purple in the wild, to near blues in cultivation. Over the years I have grown many colour forms, but I still most cherish this paler incarnation selected from a plant growing in the Cornish garden of its name. Height 2-3m. Origin Garden origin (species China). Conditions Acidic soil; partial shade. Hardiness RHS H4, USDA 5a-9b. Season of interest Spring.