May in the Garden

May has to be my favourite month in the garden.

Everything’s so fresh and green, and some of my favourite plants are coming into flower now.

Floral & Hardy’s Top Ten Plants for May:

image of Aquilegia

Aquilegia – 

‘Columbine’ or ‘Granny’s Bonnet’ – an old cottage garden favourite with pretty ferny foliage and dainty flowers with long ‘spurs’. They come in many colours and self-seed freely around the garden. They reach 60-90cms tall depending on variety. Plant them near to the front of the border so you can see the delicate blooms.

image of Azaleas

Azaleas and Rhododendrons – 

Actually azaleas are rhododendrons too, but we tend to think only of the larger leathery-leafed evergreen species as rhododendrons. The deciduous and smaller oriental types, we think of as azaleas. Many of the colourful deciduous varieties are beautifully scented. Generally speaking the azaleas can take more sun than the rhodos, but all need an acid soil. Try and visit one of the open gardens in your area this month to see spectacular displays. You can find out where they are from the Open Garden Scheme or from the RHS.

image of Ceanothus Concha

Ceanothus ‘Concha’ (AGM) – 

‘Californian Lilac’ – one of my absolute favourite garden shrubs, this has the deepest of blue flowers in profusion. It can grow quite large (about 3ms tall and wide) so you do need space for it, but it’s worth it. Try growing a pink Clematis montana through it for a lovely colour combination, and later flowering Clematis to prolong the flowering season.

image of Cercis canadensis 'Forest Pansy'

Cercis canadensis ‘Forest Pansy’(AGM) – 

Judas Tree – despite its unfortunate common name – given because it was believed to be the tree Judas hanged himself from – this is a really pretty small garden tree. The deep pink flowers give a dramatic display on the bare branches and these are followed by heart-shaped, deep purple leaves, turning yellow in autumn. It will eventually grow about 10ms tall.

image of Choisya ternata

Choisya ternata (AGM) – 

‘Mexican Orange Blossom’ – so called for the sweetly scented white, star-shaped flowers. This is such an easy shrub to grow and I use it a lot in my designs. It’s evergreen and so also makes a good foil for other flowering plants later in the season. There are several different varieties – some with finely divided foliage and some with lime green leaves. It makes a rounded shrub about 1.5ms tall and wide.

image of Convallaria magalis 'Lily of the Valley'

Convallaria magalis – 

‘Lily of the Valley’ – an easily overlooked plant, as it only reaches about 25cms high, until that is, you get a whiff of its wonderful fragrance. The bell-like flowers are generally white and their scent has been used for making perfume for centuries. They make good ground cover in woodland or shady borders. Fit for a future queen!

image of Dicentra spectabilis 'Bleeding Heart'

Dicentra spectabilis (AGM) – 

‘Bleeding Heart’ – so named for the shape of its pendant flowers, this is another plant that prefers woodland or shady conditions, although it will tolerate sun if the soil is moist. It has attractive ferny foliage and is also available in white. It grows to about 60cms tall.

image of Paeonia suffruticosa 'Tree Peony'

Paeonia suffruticosa – 

Tree Peony – we’re probably all familiar with the herbaceous peony with its large blousy, blood red flower, but the tree peony is less well known. They make large shrubs (to about 2ms) with attractive deeply cut foliage and big bowls of papery petals in red, pink, white or yellow. They’re not hard to grow, just give them a sunny, sheltered site and stake the flowers if they’re too heavy!

image of Papaver orientale 'Oriental Poppy'

Papaver orientale – 

‘Oriental Poppy’ – what can I say – big, bold and beautiful. These flamboyant flowers are available in colours ranging from white to deep red, but most have black bases to the petals and prominent black anthers. In recent years the variety ‘Patty’s Plum’ has been very popular, but I like the brighter, orange-red blooms of ‘Marcus Perry’. The only down-side is the fact that the foliage dies down after flowering, so cut back and plant other perennials around them to fill the gaps.

image of Polygonatum hybridum 'Solomon's Seal'

Polygonatum hybridum (AGM) – 

‘Solomon’s Seal’ – another old cottage garden plant, but its elegant form and flower would look just as good in a contemporary scheme. Its graceful arching stems grow to about 1m high and carry pendant green-tipped, white bells. It’s another one for the shadier parts of the garden.


1. Stake herbaceous plants if you haven’t already done so, particularly tall specimens like delphiniums, to stop the precious flowers being broken off.

2. You can still sow hardy annuals such as nasturtiums, marigolds and sweet peas where they are to flower if you’re quick, otherwise you can sow some perennials outdoors now, such as Lupins, Delphiniums and Achilleas.

3. If you sowed annuals last month you should be ready to thin them out now. On average you should leave about 10-15cms between them but obviously that will depend on the size of the mature plant, but make sure you keep the strongest looking specimens.

4. If you didn’t mulch around your plants earlier, either with good home-made compost, well-rotted manure or bark, do it now to help keep the moisture in the soil.

5. Keep looking out for pests such as aphids and caterpillars and deal with them promptly by whichever method you prefer.

6. Any dead shoots on climbers such as Passiflora (Passion Flower) and Trachelospermum (Evergreen Jasmine) can be pruned out now, and, if it’s got too rampant, old favourite Clematis montana can be cut hard back now, immediately after the flowers have faded.

7. Formal hedges can be cut back to shape this month, although be careful if you have Leylandii that you do not cut back into old brown wood, as this plant does not regenerate.

8. If you have a new pond and are starting to get an algae problem, don’t be tempted to empty the pond and start again, as this will only prolong the problem. Instead remove the blanketing algae by twirling a bamboo cane in it to get it all out, then make sure you have some good aquatic planting to grow on and cast some shade over the pond, such as Water Lilies and Water Hyacinth . Oxygenating plants are also very beneficial and your local aquatics shop can advise you.

9. Early May is really the last chance to sow new lawns

10. Finally, make sure you are watering and feeding everything regularly from now on, especially in periods of dry weather.

By Helen Ellison, Floral & Hardy’s Garden Designer

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