"Summer exuberance"

Warm-climate plants love the heat!
Sunday, 20 January 2019     

Hibiscus rosa-sinensis hybrid, possibly Apple Blossom

If the current heatwave in Sydney has any messages, one of them for me it is that using warm-climate plants in our gardens makes more and more sense. In high summer, Sydney gardens can show their semi-tropical side, if filled with plants that thrive in the heat. The plants keep right on growing through the hot months, and can make the garden look so full and exuberant at this time of year. Before I added these plants to my garden, it was fairly bereft of colour in summer; I now rejoice in their glowing jewelled hues amidst luxuriant foliage. Our hot (and getting hotter!) summers enable us to grow a wide range of subtropical annuals, perennials, vines, shrubs and trees which are too tender or which sulk in cooler climates but which flourish in our warmest weather, usually continuing blooming well into autumn.

In my own garden, I never embraced a completely full-on tropical style garden with palms, cordylines, banana trees and other dramatic foliage plants, but sought instead warm-climate flowering shrubs and shrubby perennials to create my own peculiar version of English herbaceous borders with colour, texture and a profusion of flowers over as long a period of time as I could manage. Decorative warm-climate foliage plants are added into the mix for dramatic effect, and semi-tropical annuals self-seed in gaps to provide ribbons of bloom amongst the other plants.

Dahlia and Canna provide brilliantly coloured flowers for months on end, in a rainbow of hues. Both come in a range of heights, with compact specimens suited for smaller spaces or pots. Other good performers include a number of summer-flowering Salvia shrubs: probably the most floriferous being 'Amistad', with its seemingly endless array of spires of rich purple flowers. Smaller salvias such as those from the 'Mesa' and 'Heatwave' ranges also bloom well for months on end, in an array of colours.

A stalwart small shrub that sails through the hottest weather is Pentas. A rounded plant up to about 1 m in height, it is covered in posies of tiny star-shaped flowers in colours of pinks, purples, mauve, white and red. A number of Acanthaceae plants are also in bloom throughout the hottest months: the shrimp plant (Justicia brandegeeana), with quirky inflorescences of crimson, rusty-red or lime-yellow; the so-called white shrimp plant (Justicia betonica), with its upright white spires, looking very good at the moment; Justicia carnea, with its chubby pink or white plumes; Brillantaisia subulugurica, with its striking panicles of purplish-blue, claw-like flowers; and Pachystachys lutea, with its golden candelabra blooms. All of these shrubs will grow in part-shade as well as sun.

In recent times, I have been growing a Hawaiian-type hibiscus (Hibiscus rosa-sinensis) successfully for the first time, and it is melding in well with the rest of my semi-tropical plants, and producing opulent, pastel-pink flowers each with a deep red maroon that add an exotic flavour to the garden. It is possibly the cultivar 'Apple Blossom'. Another plant I am pleased with is Mussaenda frondosa, a plump, wide shrub 2-3 m tall bedecked with small orange flowers with large, attractive white bracts that look like bunting draped through its branches. It looks effective in a border with white flowers and white-variegated foliage plants. There are cultivars with other coloured bracts, such as pink and red, but they seem to need milder winters than we experience in Sydney. Other tropical-looking shrubs I grow include the angel trumpet (Brugmansia) and Lepechinia salvae with its arrow-shaped foliage and spikes of raspberry-hued flowers.

Coloured foliage lends itself to creating an exuberant semi-tropical-style look, and amongst my favourites are Iresine, which has forms in hues of cerise, purplish-brown and yellow-striped green; and coleus, with myriad variations of colour and pattern. My current pet has brilliant orange leaves, pairing nicely with a delightful dwarf Canna with neon-orange blooms. Some of the Canna themselves have decorative colours on their bold, paddle-like foliage, such as the yellow-veined 'Striata'; and striped orange, red, green and bronze in the popular 'Tropicanna'. A yellow-variegated leaf ornamental ginger (Alpinia zerumbut 'Variegata'), has stunning yellow/green variegated foliage (ht 1.5 m). It is an excellent plant to bring light and colour into gloomy parts of the garden; it also is in flower now, with trusses of creamy-coloured, waxy buds opening to reveal yellow and red shell-like blooms. The metallic purple leaves of Strobilanthes dyeriana and the velvety silver foliage of Plectranthus argentatus are also favourites for stunning leaves.

Warm-climate, self-seeding annuals that have found a place in my summer garden include the brilliant blue Browallia americana, the burgundy-tasselled Amaranthus caudatus, tall, airy Verbena bonariensis, the brilliant orange-apricot bracts of Euphorbia cyathophora and lime-green Nicotiana langsdorffii. I do pull hundreds of seedlings up when they appear, just leaving a few here and there, otherwise my garden would be overrun!

I relish the lush - almost rampant - growth of these plants at this time of year, when it can be a battle to walk down garden paths with jungle-like foliage blocking the way, and the blowsy explosion of flowers that is so very, very different from springtime! To grow to their full potential, these sorts of plants need humus-rich soil and sufficient moisture. After my horrendous water bill last summer, I am relying on my drip irrigation system this year, assisted by applications of a soil-wetting agent and plenty of mulch. So far, the plants are holding up OK, despite the terrible heat of this past week in Sydney. Regular deadheading keeps the flowers blooming: and that's about the limit of gardening for me right now, whilst the heat is forecast to go on ... (but thank goodness for a cool respite this weekend just past!)

 Reader Comments

1/6  Margaret - 2122 (Zone:10 - Warm Temperate) Monday, 21 January 2019

Great blog - you have suggested so many plants which flourish in our hot/humid summer. Cosmos, zinnia, canna, dahlia, all provide colour and enjoy the heat. My cane begonias, although liking some shade, do also enjoy the heat, and are dripping with flowers. I don"t grow hibiscus, but am interested to acquire the Hibiscus rosa-sinensis and also try the Mussaenda. My snail vine has completely covered an arch and this year I planted a chocolate vine, which is growing well, so far, without flower. Thanks, Margaret. Your garden must be looking fab at the moment. Deirdre

2/6  Valerie - 2121 (Zone:10 - Warm Temperate) Monday, 21 January 2019

Thanks for mentioning the Salvia Amstad. I bought one at the Epping Cottage Garden Club meeting, planted and then forgot what it was. It has the most beautiful purple flowers. Thanks too for mentioning Canna - am trying a yellow one out for the first time and so far so good. I appreciate what you mean by the horrendous water bill. I"ve just put a drip irrigation on a row of camellias to save the hand watering. Thanks, Valerie. Because we have had some showers of rain this summer, it is not as dire as last year and my drip system seems to be working. I have not run the sprinklers this year (yet)! Deirdre

3/6  Pamela - 2158 (Zone:10 - Warm Temperate) Monday, 21 January 2019

Great to read your blog and note all the same plants in my own garden. Colour everywhere with coleus, seeded cosmos,begonias,Angelonias & creeping ipomeas. My Mussaenda finally settling in and looking happy.Roses flushing again and foliage reigns supreme with Iresine, Cannas, Plectranthrus, golden Duranta and Alternantheras glowing.Salvia Amistad & Mystic Spires never stop flowering. Choosing the right plants as you say is key, arent we lucky to have so much colour now i i.! It sounds wonderful, Pamela! Deirdre

4/6  Sue - 2074 (Zone:10 - Warm Temperate) Tuesday, 22 January 2019

A helpful blog - thanks. My garden is lush & exuberant especially with weeds. Being out of action I see some things have died and others look great especially begonia fuchsoides. S.Amistad is on my list now, thanks. Salvia oxyphora, is doing well with its pink furry blooms. Unlike Margaret my snail vine is rubbish this year - think too much in the shade. My water bill will be down this year as only a bit of watering done by the better half. So thankful for the rain on Monday morning. The rain was a lovely surprise on Monday morning. The begonias are really enjoying the heat. Deirdre

5/6  Kerrie - 2104 (Zone:10 - Warm Temperate) Wednesday, 23 January 2019

Hi Dierdre, aren"t the Cannas wonderful this year! A couple of questions, is Salvia Amistad one that suckers & spreads? Had to remove one this year that looked like this due to it wanting to take over. It was a cutting so I never knew the name. Such a pretty flower! Have you ever thought of doing an open garden? To benefit a charity perhaps? I"m sure lots would love to see your garden. Kerrie, I have heard some people say Amistad spreads; in my own garden it has clumped up but has not sent out suckers in all directions like some of the really bad salvias such as S. guaranitica or S. uliginosa. I am keeping an eye on it, though. Have had my garden open in the past for garden groups but am not planning to do it again in the foreseeable future; it is a lot of work! Deirdre

6/6  Maureen - 2118 (Zone:10 - Warm Temperate) Wednesday, 23 January 2019

Another great inspiring blog Deirdre, after such hot summer which has caused grieve to some plants but amazingly they look like surviving the ordeal. Am resisting pruning off burnt leaves though. Yes I gathered during last visit to your garden you had had a frightening water bill!! I am trying to be very good with watering this summer, and so far, so good, despite the awful heat. Deirdre

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