AUGUST PLANTS
As summer reaches its peak, two richly coloured glaidioli, a delicate sunflower and strong-growing, pale-blue ipomoea feature among Tom’s top picks
CANNA ‘EREBUS’
There aren’t many of these water cannas around and this cultivar of Canna glauca is one of the best in terms of reliable, flowering performance. You can grow it in water margins or water-logged containers, submerging the roots throughout the summer. But it is equally happy flowering in a fertile garden soil. Treat it like any other canna, by allowing the first frost to slightly blacken the foliage and then bring it into a frost-free place for the winter. I have learned not to cut the foliage down until new growth emerges in spring. AGM*.
Height 1-2m.
Origin Garden origin (species from South America).
Conditions Poorly drained soil; full sun. Hardiness RHS H3, USDA 7a-10b. Season of interest July until first frosts.
HELIANTHUS DEBILIS ‘VANILLA ICE’
Sunflowers can be troublesome when it comes to their heavy f lowerheads and can demand strong staking techniques to see them through the latter part of the summer. ‘Vanilla Ice’ is a more delicate, multi-branched individual, and as such is far less demanding.
I grow this highly f loriferous cultivar for cut f lowers. The stems are wiry and the f lowers are very useful in arrangements with other summer blooms, such as yellow zinnias and blue statice.
Height 1-2m.
Origin Garden origin (species from USA and Central America). Conditions Moist but well-drained soil; full sun.
Hardiness RHS H2, USDA 9a-11. Season of interest July – September.
GALTONIA CANDICANS
Galtonias are widely available but as with a number of summer-flowering bulbs, they’re not used quite as often as they should be. I generally start these bulbs off in pots at the beginning of the year and plant out a strong specimen in the spring. Spikes of tiered, bell-shaped, white f lowers appear in the summer and give a boost of colour and elegance to mixed borders and containers. Galtonias work well when planted in small clumps throughout a planting scheme to give an effortless and natural feel to your plantings. They’re also great for containers. AGM.
Height 50cm-1m.
Origin South Africa.
Conditions Moist but well-drained soil in growing period; full sun.
Hardiness RHS H4, USDA 6a-10b. Season of interest Late summer.
GLADIOLUS ‘BIMBO’
If you enjoy the increasingly popular trend of combining creams, dusky pinks and apricot hues, then this summer corm will make a great addition to your planting schemes. There is an antique, coppery quality to its tones that really makes it stand out from the crowd. As with most gladioli, you should plant from April onwards, in clumps where the plants are to flower, and staggered planting will give a longer flowering period. To ensure perenniality, lift the corms after the first cold spell and store in a dry, frost-free place until the following growing season.
Height 1.5-2m.
Origin Garden origin (species from South Africa).
Conditions Fertile, free-draining soil; full sun.
Hardiness RHS H3, USDA 7a-10b. Season of interest Mid to late summer.
IPOMOEA ‘CAPRICE’
I trialled several morning glories last year and they were surprisingly variable in their performance, but this was one of the best blues. Strong growth covered my 2m-high obelisk in foliage and pale-blue flowers erupted all over this plant. It was quite a spectacle, especially alongside some of the less floriferous forms. Avoid over feeding or you’ll end up with lots of leaf and only a few flowers, but other than that, in a sunny position, ipomoeas will provide lots of colour and interest well into the summer and cover up some of those less attractive fences.
Height 1.5-2.5m.
Origin Garden origin (species from Mexico).
Conditions Moist and well-drained soil; full sun.
Hardiness RHS H1C, USDA 9a-11. Season of interest July – October.
VERNONIA ARKANSANA ‘MAMMUTH’
Tall border plants can be hard to get right. They need to provide that essential, back-of-the-border, top tier, while also offering prime flowering performance. Vernonias provide both. I’ve discovered them only recently, and was immediately entranced by these sophisticated and intriguing late-summer stars. With their dark-purple flowers, carried on tall, stately stems, they offer a late burst of colour to a border.
Height 1.5-2m.
Origin Garden origin (species from Northern and Central USA). Conditions Tolerant of most garden soils with good moisture retention during summer months; full sun. Hardiness RHS H7, USDA 5a-8b. Season of interest Late summer through to autumn.
ZINNIA ELEGANS ‘BENARY’S GIANT WINE’
I grew a number of taller-stemmed zinnias in 2017, and the ones that stood out head and shoulders above all the others were those from the wonderfully consistent Benary’s range. They are available in a variety of colours, with one to suit almost every taste. This one from the Benary’s Giant Series is a classy plant, with sultry mulberry-coloured flowers. It is perfect grown as a cut flower, but will also have a strong presence in your borders until the first frosts.
Height 50cm-1m.
Origin Garden origin (species from Mexico).
Conditions Moist but well-drained, fertile soil; full sun.
Hardiness RHS H2, USDA 9a-11.
Season of interest Staggered sowing will produce flowers from July until first frosts.
TITHONIA ROTUNDIFOLIA ‘ TORCH’
Tall, vibrant and blisteringly brightorange flowers appear on this Mexican sunflower as the summer warms up. Grow as an annual and plant in full sun in reasonable garden soil to achieve a strong two metres of growth. Tithonias will keep flowering until the frosts (don’t forget to collect the seed). This is a strong cultivar with consistent dark-orange flowers that are hard to beat in mixed and exotic plantings. They detest the cold so resist planting them out until June.
Height 1-2m.
Origin Garden origin (species from Mexico and Central America). Conditions Well-drained, fertile soil; full sun.
Hardiness RHS H2, USDA 9a-11. Season of interest Midsummer to autumn.
DAHLIA ‘BLACK JACK’
I’d be more than happy to grow this dahlia for its foliage alone. Its strong architectural, glaucous foliage appears in the early summer and complements a number of garden plants. I’ve grown it alongside the earlier performing Potentilla ‘Gibson’s Scarlet’ to act as a foil to the fiery red blooms. As the year rolls on, very large and rich cactus f lowers of the darkest maroon appear on very strong stems. Almost shrub like in its habit, this dahlia works on many levels as a garden plant – a welcome cutting f lower too.
Height 1.5-2m.
Origin Garden origin (species from Mexico and Central America). Conditions Well-drained, fertile soil; full sun.
Hardiness RHS H3, USDA 7a-10b. Season of interest July until first frosts.