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