Tohm's A - Z of Plants. H is for Heliconia



What sculptural splendour!



The Heliconia is the flagship of exotic plants. Commonly known as Crab Claw or Lobster Claw there are not many flowers as ostentatious as these.

Used by the florist trade throughout the world, many types of Heliconia travel well and last for a long time as cut flowers. They are also a fabulous landscaping plant offering a variety of sizes; from 50cm with the shade loving H. stricta “Dwarf Jamaican” to the 6 metre giants such as Kawauchi. You will need a lot of room for some of them.

Mostly Heliconia prefer full sun with a few exceptions. If you are looking for a good shade lover, try H. angusta “Red Holiday”- it will add a splash of colour to your winter garden.

There are clumping and running Heliconia. The clumpers will spread out slowly, proving themselves more suited to a smaller garden. They will deplete the soil of nutrients rapidly, requiring fertilizing in early spring and mid summer. Cut off the dead flowers and when the new season growth is coming on, cut last year’s shoots right back to the ground. This will leave the clump looking fresh and healthy.

If you prefer a running variety, such as any of the H. psittacorum cultivars, you as the gardener need to consider how you will you control the spread. Large underground pots or root barriers will contain the plant, though after about three years the plant will need to be dug up and a few rhizomes replanted. If on the other hand you prefer to let them run free, they will send flowers up through other small shrubs and can be an attractive way to stabilize banks.

Heliconia grow best in well drained, moist soil with a regular supply of mulch and dug-in compost. I knew of one clump of H. stricta growing well between two Alexander palms for many years until one summer it just upped and died. The reason for this was that the palms and Heliconia were so happy in their place that their roots and rhizomes raised the ground level, hence blocking the flow of water. The Heliconia effectively spent two months in a bog and rotted, proving that too much of a good thing can kill you.

Scale, grasshoppers, mealy bugs and lack of organic matter are the main health issues facing Heliconia. The latter can lead to a general lack of vigour, making the plant more susceptible to attack by the three insects. If the plant is in poor soil and exposed to the sun with inadequate moisture in the soil it will tend to look pallid with mottled or spotted foliage. The plant is most likely to be ready to be lifted and replanted in rejuvenated soil.

Go on a tropical holiday every time you visit your garden by combining Heliconias with Cordylines. You will be the envy of your visitors from down south.

Tohm's A-Z of Plants. G is for Gardenia

Perfection itself

I often get carried away when talking about the beauty of particular plants. There are so many which seem to have a lot to offer and Gardenia is no exception. The glossy leaves make the plant an attractive addition to the garden without the even considering the flower.

The genus, Gardenia, contains around 200 species ranging in size fro mounding ground covers to trees of around 15 metres tall. Species can be found in Africa, Australasia, Asia and Oceania. Northern Australia hosts several native Gardenias.

The most commonly cultivated variety, Gardenia jasminoides (syn. G augusta) originates from China. Over the centuries hybrid varieties have been bred to give us Gardenia ‘Radicans’ at 25cm high, through to Gardenia ‘Magnifica’ at  about 2 metres tall, with many sizes in between. I will focus on the cultivation of these.

They are renowned for their incredibly fragrant rose like blooms. These are either single or double whorls of clean white or occasionally golden cream petals. The flowers last well even when cut with a short stem, making them very popular in posies or as a button hole flower. Be careful not to bruise the petals.

The deep orange fruit, residual on the plant long after the flower has gone can be used for yellow dye in textile and foods. The petals are sometimes used to perfume tea.

Gardenias love humus rich, friable soil. The pH needs to be acidic, which is generally not hard to achieve on the Sunshine Coast.

Prior to planting, dig a manure rich compost 200mm into the soil and supply additional composted manure or organic fertiliser in early spring and again in early summer to ensure healthy foliage and abundant flowers. A common problem with Gardenias is a yellowing of the leaves. This is generally caused by a magnesium deficiency and can be remedied by a general purpose fertiliser with trace elements or a small dose of Epsom salts. Inadequate or inconsistent watering can also bring on leaf and bud drop. In long dry periods, mulch well to conserve water and either prune the plant back after flowering to reduce its requirements or water if permitted.

While they enjoy bright light, Gardenias prefer protection from the blasting afternoon sun of summer. Plant on the eastern side of a building or large tree.

In cooler areas, plant them against a north facing wall to protect them against the cold and frosts of winter.

They are shallow rooted plants. Disturbance to roots during flowering will cause the buds to drop. However, they do transplant quite well if moved or re-potted in autumn with the shallow roots providing a smaller, more manageable root ball.

Gardenias can be use for standards, hedging or as a back ground plant in garden beds. Any of the larger, common Gardenias make excellent specimen plants.

Pests, unfortunately, are a common part of growing Gardenias. Scale and mealy bugs will attack the upper reaches of the plant, usually resulting in the unsightly sooty mould. These pests are more prevalent if the plant is struggling for light or water or, if it is fighting against weeds. Sort out these problems first then if needed monthly sprayings with a horticultural oil when the problem is recognised will clear it up. Nematodes can also attack the roots of the plant, causing the leaves to yellow and fall. Companion planting with some annuals such as Marigold may alleviate the problem. In sandy soils, ensure dig a large amount of compost and manure into the ground before planting.

Aphids and White flies can also attack Gardenias.

Generally, the healthier a plant is, the less likely it is to be attacked by pests and diseases.

Find a spot outside a window or near your dining area to make the most of the heady scent from the Gardenia.

Tohm's A - Z of Plants. F is for Festuca

What a perky little fellow!

A plant species that has become popular in recent years as a part of the low water garden is the Festuca. The reason for this is its predilection for well drained soil, making them quite at home in rockeries, open fields, borders or arid landscapes. Commonly known as Fescues, they can handle periods of dry weather and are not bothered too much by frosts. They are also tolerant of salt spray making them ideal for coastal garden.

Festuca means stalk or stem in Latin, which accounts for its tufted, grass-like appearance. This also makes it an attractive and low maintenance addition to a garden.

Fescues are found throughout the world, with Australia boasting 9 native species, along with 4 exotic species which have become naturalised. Their flowers can range from insignificant to prominent plumes that create a classic mist-like aura around the plant. The foliage can be gold, green or blue/grey, depending on the variety. 

They are best grown in full sun, although they can handle some shade. In our climate, too much shade during the warm wet months may result in the plant rotting.

 Festuca glauca or Blue Mountain Grass is one of the most common ornamental forms with its distinctive 30cm high mound. This gorgeous grass is popular in contemporary landscaping either as a mass planting surrounded by feature pebbles or in contrast with grasses of other colours such as Pennistum setaceum (Red Fountain Grass).

Keeping your fescues looking their best is a simple task. Like many ornamental grasses, when your plantings start to look a bit tatty just give them a hair cut and they will bounce back all bright eyed and bushy tailed.

Propagation of some species can be by seed, though for the home gardener, dividing the clumps in spring just as the new season’s growth is kicking is an easy way to provide many new specimens quickly. Trim the blades back to about 70mm and set into potting mix in a small pot or 50mm tube. Don’t forget to fertilise. Keep them well watered, then in 4 – 6 weeks you should see new shoots appearing out of the top and fine hairs creeping out of the base of the pot. They are now ready for planting.

Because some species are classified as weeds, care should be taken if you collect your own seeds from the bush.



Tohm's A - Z of Plants. E is for Euphorbia

Revered in its native Mexico, the Poinsettia (Euphorbia pulcherrima) is also known as the Christmas Flower. In this part of the world however, we see it flowering in late autumn and early winter.

It is in fact a member of one of the largest genuses in the plant kingdom. There are over 2100 species in the genus Euphorbia ranging from tiny herbaceous plants growing between your pavers through to an amazing array of succulents, and even some very beautiful woody shrubs.

While having many varied forms, all Euphorbias have two things in common. They all produce a corrosive white sap (latex) to deter animals from eating the plant. They also have fairly simple green or yellow flower. The showy displays that many Euphorbias’ are prized for are actually the bracts, a modified leaf.

Most cultivated Euphorbias prefer sunny aspects with the shrubby varieties developing an open leggy habit if grown in too much shade. If a more compact shrub is required, especially with the Poinciana and Snowflake (E leucocephala), prune very low as soon as the coloured bracts start loosing their appeal. Tip prune regularly throughout spring until around the end of January. This will encourage many lateral shoots, each of which will support a flowering head.

Propagation of the shrubby varieties can be done using soft tip cuttings in summer- struck in a glass house at high temperatures of around 25-30 degrees Celsius, or with woody stem cuttings from winter to spring. For the succulent Euphorbias, remove stem sections in spring or summer and leave exposed for a few weeks for the wound to callous, then pot out into a well drained, sandy, striking mix.

The sap can do damage if it comes into contact with mucous membranes and may even cause blindness. Therefore, care should be taken when handling most members of this genus. Immediately wash off any sap that you come into contact with. If the sap has already started to congeal it will no longer be soluble in water. Clean it off with milk or moisturising cream instead. It’s interesting to note that this potent sap has been used medicinally to heal wounds and stomach disorders. A common name for some varieties is Spurge derived from the old French term ‘espurge’, to purge. Do not self medicate with the sap, as poisoning is a possible side effect.



A beautiful display of  Poinsettia and Snowflake



Tohm's A - Z of Plants. D is for Doryanthes

Splendid in their form and colour

For a native plant that provides dramatic visual effect, you can’t beat Doryanthes. The genus Doryanthes contains only two species, both of which are among the largest lilies in the world.

The Gymea Lily (D. excelsa) originating from a region around Sydney provides a spectacular flower display on a stem 3-6 metres high. You need to be pretty tall or have a high vantage point to get the most out of this flower. The Spear Lily (D. palmeri) native to northern NSW and south east Queensland also produces its flower on a large stem though this bends over providing a stunning flower at ground level.

Both have sword like leaves up to 3m long and large red flowers on very large red terminal heads (about 500mm across). Sweet nectar is produced over a period of several months attracting many nectar feeding birds to your garden.

Doryanthes plants prefer to be grown in full sun or part shade and will rot if the soil is boggy. While its foliage is frost tolerant, the developing flower needs to be protected.

As the plant grows larger, its stem draws deeper into the soil giving it the ability to withstand extended dry periods. It does however require deep friable soil to perform this task. The growth of a Doryanthes plant will be restricted in heavy clay soil. I know of a 10 year old plant in these conditions which is less than 1m high.

The Doryanthes will present well as a pot specimen for a number of years and is a good alternative to the more delicate Agave attenuata. Be aware that the plant will not be restricted by its confined quarters, preferring to break out of the pot as its stem swells. If planting in your favourite ceramic pot, be sure to pot up or plant out early enough to avoid the problem.

From seed, the Doryanthes will take 8-10 years to flower. So the gardener who cannot wait that long should obtain an advanced plant. Otherwise, be patient and enjoy the foliage until the flowers eventually arrive.

Tohm's A - Z of Plants. C is for Curcuma

Makes a gorgeous cut flower
that lasts for weeks

This gorgeous member of the ginger family fits under an umbrella known as tropical gingers. Originating from tropical Asia through to Northern Australia, there are approximately 80 species of curcumas and hundreds of cultivars.

Unlike many other gingers, curcumas die back in autumn with lush foliage emerging again in mid spring earning it the nickname of Hidden Ginger.

All have stunning flowers ranging from 50mm to over 300mm, with such a broad spectrum of colours that even the fussiest of gardeners will be satisfied.

Curcumas are the ideal sub-tropical alternative to temperate bulbs and are an easy plant to keep providing a few simply rules are followed.

1. Some like sun while others prefer shade, so research your choice and plant with the appropriate aspect.

2. They do not like winter water. Plant them in soil which is well drained and rich in organic matter. Remember, they originate from the rainforest floor.

3. When the spring shoots appear, fertilize well and ensure an adequate water supply.

4. Mark the spot where the plants are so you don’t accidentally dig them over during the winter.

Tumeric (C. longa) is probably the best known of the species. Here are a few other varieties that I would recommend. For a full sun position, try the ‘Siam Tulip’ (C. alismatifolia) or ‘Voodoo Magic’. If the aspect is more filtered light, ‘Jewel of Burma’ (C. roscoeana) or ‘Jewel of Thailand’ (C. cordata) are ideal choices. If you prefer natives, the ‘Cape York Lily’ (C. australasica) is the plant for you.

Curcumas make great pot plants as they can be hidden away behind the shed during winter and brought out as a stunning display when the flowers appear. It is important during winter not to water curcumas as the rhizome will rot. A great way to ensure this is to simply lay the pot on its side.

Some varieties are fantastic as cut flowers, lasting for weeks in the vase. Curcuma plants are usually only sold when flowering and will be available in the shops from around Christmas.

Tohm's A - Z of Plants. B is for Bracteantha

Little rays of sunshine in the garden

Botanical names of plants are used to help avoid confusion created by several plants using the same common name or a plant having various common names. But occasionally the classification of a plant can lead to more confusion for the home gardener than common names.

A great example of this is a plant most of us know as the Paper or Everlasting Daisy. The genus has had four names since it was first described in 1803 with many species drifting in and out of the club as studies intensified. Many of us would have grown up knowing it as Helichrysum bracteatum. In 1991 it was reclassified as Bracteantha bracteata, a name under which it is still marketed today. However, one year before that classification, Russian botanist Nikolai Tzvelev had assigned it the name Xerochrysum bracteatum which is currently the plants official botanic name.

Fortunately this confusion has no impact on the plant’s growth or popularity with cultivars receiving awards around the world.

The strawflower is a member of the Asteraceae or daisy family and can be found growing naturally in most regions of Australia except the tropics. It is best known for the stunning daisy flowers which retain their colour even when removed from the plant and dried. The flower head is surrounded by layers of stiff paper like bracts which are a modified leaf, not a petal. These blooms are often used in dried flower arrangements and potpourri.

It can be treated as either an annual or perennial depending on the region it is grown. Wet summers of the sub tropics often lead to rot at the base of the stem. Plant out fresh ones in late autumn to provide your garden with the glowing flowers through to Christmas.

Strawflowers are versatile in the home garden. They can be used in rockeries, cottage or bush gardens and annual garden beds. They can be grown from seed, though the colour of the flower and the size of the plant may vary. If a consistent plant size and colour is required, select one of the many cultivars available. These have been carefully bred since the mid 19^th century to provide us with a wide range of stronger colours. Modern varieties are often more compact than their wild or seeded cousins.

This is a particularly drought tolerant plant making it useful to the gardener who does not water their garden. Plant out in full sun into well drained, slightly acidic soil.

Dead head throughout the flowering season to ensure bushiness and more blooms. If grown as a perennial, prune back old woody growth early in winter.

No matter where the name changes take us in the future, the Helichrysum/Bracteantha/Xerochrysum will continue to be an important and outstanding flowering plant in gardens throughout the world.

Tohm's A - Z of Plants. A is for Austromyrtus

A midyim berry ready to eat!

Once considered much larger, the Austromyrtus genus has recently undergone a bit of pruning leaving it with only 3 species. They are a genus of shrubs found in the Myrtaceae family, which includes plants such as tea trees, bottle brushes, lilypillies and eucalypts. The name is derived from Australis, Latin for southern and myrtus, the Greek word for myrtle.

Found between Sydney and South East Queensland, they mostly appear with small white flowers of 5 petals which are followed by soft edible berries. These are a great attractant for small birds. Known as a source of bush food, Austromyrtus species and their cultivars have well and truly endeared themselves to the home gardener due to their splashes of colour, versatility and hardiness.

The most common of this genus, Austromyrtus dulcis, is a spreading heath land shrub, equally at home on the range.  Also known as the Midyim berry it will grow to 0.5 m high and up to 1.5m wide. After a blanket of beautiful small flowers in Spring, the Midyim will fruit profusely through early Summer and to a lesser extent in Autumn. The fruit are sweet with a mild cinnamon taste and are quite aromatic. I have found this to be a favourite among young children who will happily sit for long periods beside a shrub while they graze on the fruit.

It is interesting to note that the local costal region of Mudjimba has been named using an indigenous word meaning –‘place of the midyim shrub’.

Popular cultivars for the Austromyrtus are sold as ‘Blushing Beauty’ and ‘Copper Tops’. Both are small, compact shrubs with beautifully coloured foliage in the red hues. These can be pruned into an attractive low hedge or included in cottage style gardens.