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Calla lilies (Zantedeschia)

Top left: Callafornia Red, Top right: Super Mac, Bottom left: Festival, Bottom right: Red Alert

Calla lilies, or Zantedeschia, are very brightly coloured (unless they’re white, of course) and have an elegant, modern look which is perfect if you fancy a change from the ubiquitous petunias and geraniums in your summer containers. The ones pictured here are some recent introductions on display at the Ball Colegrave summer showcase in summer 2019. Ball Colegrave supply to growers who supply to garden centres and online plant sellers, so you can pretty much guarantee that you’ll be seeing their plants for sale somewhere!

With zantedeschia you usually have the option of buying large plants in flower from around late April to June (you’ll sometimes see them even earlier sold as house plants – don’t put these outside until it’s warmed up). That has advantages as you’ll be able to see the exact colour (if you buy in a garden centre rather than online) and should be able to plant them straight into your containers if the risk of frost has passed. They can be a bit pricey as plants, though, and it’s much cheaper to buy the rhizomes which are not difficult to grow, it just takes a bit more planning and somewhere frost-free you can grow them on.

So, briefly, if you buy the rhizomes you can start them into growth as early as December if you want to grow them indoors, or in January – February if you want to grow them outside in the summer. The rhizomes have ‘eyes’, or raised, swollen nubs and these are on the top, so plant that side up. Plant very shallowly – the ‘eyes’ should be just visible at the surface of the compost. As always, use a good quality, free draining compost. It might be best not to add controlled-release fertilisers (though I usually recommend them) as it’s best not to over-feed callas and not to feed them when they’re in flower. Place them somewhere light and warm and keep them watered regularly so the compost doesn’t dry out, but don’t let the compost get soggy. Let them grow on until the risk of frost has passed, feeding with a high nitrogen feed at this stage, then harden them off gradually by leaving them outside during the day and bringing them in a night for a week or two, then plant them outside. Stop feeding when they start flowering as they don’t like too much fertilizer. Once flowering is over, a high potassium feed such as tomato food helps feed the rhizomes. Keep watering regularly and they should flower for a good couple of months.

If you want to keep them for another year, treat them a bit like dahlia tubers. You might be able to leave them outside in mild areas if they’re protected (if you can move the pot to a conservatory or greenhouse for example), but for better flowering you should dig them up, let them go dormant and store them in trays of compost so they don’t dry out, in a cool, frost-free, dark place until you want to start them into growth again.

Incidentally, the coloured part isn’t actually a flower it’s a modified leaf or bract that’s called a ‘spathe’, and the flowers are small structures that are situated on the fleshy finger-shaped growth in the middle which is called a ‘spadix’. So now you know!

Veronica longifolia ‘Charlotte’

First introduced around six years ago, this isn’t brand new but has so much to offer that I’m going to overlook that.

The elegant spires of veronica are perfect for breaking up the rhythm of all the more rounded flower shapes in the border. On ‘Charlotte’ the slender white spikes are plentiful, and are set off perfectly by cream edged green leaves.

In my garden and on my allotment it flowers from late June well into August, so comes in handy if you’ve got one of those ‘spring’ gardens that tend to peter out after the glories of April and May. Its tough, too, surviving hard frosts, drought and almost complete neglect – the allotment bed it grows in dried out and then became overrun with weeds and grass last year, but this veronica still came up and flowered again this year. Veronica can suffer from mildew, but I’ve never seen it on this variety, another big plus!

Last but not least, the flowers attract many bees and butterflies. Perfect.

Delphinium ‘Cinderella’

This delphinium is not just pretty, it is said to have sturdier stems than most delphiniums, be disease resistant and to flower twice – once in midsummer and again in autumn. At around 1m-1.5m tall its reasonably compact, especially compared to some delphiniums, and the layers of petals in the flowers are said to help the blooms last longer than single flowered delphiniums. Also the flower structure, which is bushier and less linear than the typical spike, or raceme, shape, is said to add to their strength.

I haven’t grown this variety, but it won the award for Best New Plant Introduction at the BBC Gardener’s World Live show this year. Having grown many other new plant introductions over 10 years of writing a new plant article for Which? Gardening magazine, I’m more than a little wary of extravagant claims. Repeat flowering for instance, is fairly typical with delphiniums, as smaller flower spikes grow from the stem once the main spike is over, and there are a number of varieties with semi-double and double blooms so this aspect isn’t unique. However, the stems looked sturdy on the plants I saw, it was very attractive and certainly caught my eye, so it would be worth a try if you long to grow delphiniums and find all the staking and mildew impossible to manage. No amount of breeding will keep slugs at bay though!

Delphinium ‘Cinderella’ will be sold by Suttons, but after its success at Gardener’s World Live they have currently sold out of plants and it won’t be available again until May 2020. It costs £10 for one 9cm plant, or £20 for three and while these prices may seem high, they are increasingly becoming the norm for new varieties.

Clematis ‘Diamond Anniversary’

A lovely new, spring-flowering clematis (alpina type) with large, rosey-pink double blooms. Flowers start to open in April and the main flowering season will last until May. There’ll be plenty of blooms over the whole plant during this first flush of flower, though there are often a few sporadic flowers throughout the summer as well. After the flowers are over, the fluffy seed heads can look very pretty for a while longer.

It grows to around 2-2.5m tall, and has dark stems that contrast nicely with the pink of the flowers. It might be possible to grow this in a pot, though, C. alpina cultivars tend to be quite big and bushy with a lot of stems when fully grown so are probably more manageable grown in the ground. It won’t need much pruning, just a bit of tidying up when flowering finishes.

With a good flowering season and such graceful blooms, this is well worth growing.

Available from Taylors Clematis (£12), Thorncroft Clematis (£12.50) and other online retailers.

New primrose

This is primula ‘Everlast’. It looks like the native primrose, Primula vulgaris, with the same simple yellow flowers that are so pretty in hedgerows, woodland, or gardens.

But this primrose doesn’t just flower in spring. It starts flowering in early autumn and carries on through most of winter, spring and even into early summer before it finally takes a break. For most of this time it has masses of bloom and each flower seems to last for ages, so the plants don’t need a lot of deadheading.

This photo was taken in February last year and the plant had already been in flower for several months.

Its as hardy as you’d expect a primrose to be, and it looks good in borders or pots.