Plant Now: Penstemons, Calla lilies, Alstroemerias

Plant NowSummer showed up yesterday with a humid and heated hello. It had me gasping for water, so imagine how the plants must have been feeling. There are many heat lovers that can still be planted this week, though, including penstemons, calla lilies and alstroemerias.

Penstemons are herbaceous perennials that flower from late spring through summer. Although they’re not commonly grown as cut flowers, they do have a good vase life. Buy seedlings or fully grown plants at this stage and position in full sun (though they don’t mind light shade). Water well while establishing and feed twice a year, once in spring and again in midsummer or early autumn.

Calla lilies
Calla lilyIf you didn’t get around to planting your calla lily tubers back in October, don’t panic. Flowering plants are available in garden centres now. These gorgeous blooms (botanical name zantedeschia) grow well in containers or in the garden, but if transplanting in the ground, keep plants at the same level as the soil’s surface (ie, plant them no deeper than they were in the pot). Callas like a moist, free-draining soil in sun but will benefit from a little shade from the midday sun in hot areas. Water regularly and mulch to retain soil moisture.

AlstroemeriaAlstroemerias are popular because of their long flowering season, their long vase life (up to 14 days) and their extensive range of colours. They come in pastel shades to vibrant hues, in dwarf or regular size. Pick the tall-flowering perennials if you plan to pick them for the vase and plant in a spot that gets at least half a day’s sun.

Dahlias, Clematis, Calla Lilies

The weather has warmed up dramatically, so it’s time to get cracking in the garden. I’ve been sowing hundreds of flower seeds, as well as a few plants and tubers.

Dahlia tubers can be planted now for summer and autumn flowering. Plant them so their necks are 5-6cm below the soil. If they’ve already sprouted, position them so the base of the shoot is just below soil level. For detailed information on planting dahlias, click here.

My two clematis are in full bloom. Clematis montana ‘Tetra Pink’ and ‘Elizabeth’. The latter has a gorgeous chocolate scent (truly!) and both can climb to a whopping 7-10m high if you let them.

Clematis come in all shapes and sizes, from dainty diminutive blooms to giant dinner-plate show-offs. They can be compact growing or high climbers. They also flower at various times of the year, so if you plant several different varieties you can have at least one plant in flower almost year-round.

Believe it or not, clematis are superb cut flowers. Pick when the flowers have just opened and remove all foliage. Check your local garden centre for plants, or try a specialist nursery like Mr Clematis.

Calla lilyCalla lilies
Calla lily (Zantedeschia) tubers can be planted for midsummer blooming, although bear in mind that tubers under 3cm won’t produce flowers until their second year. Buy tubers from garden centres or from specialist mailorder nurseries, like NZ Bulbs.