Grafted Flowering Gums

Amongst Australia’s most popular native trees are the different varieties of Flowering Gums. While all Eucalypts/Corymbias/Angopheras flower here we are talking about trees based on Corymbia ficifolia or its hybrids.

From careful selection and breeding over many years, a variety in a good range of colours from white through to pink to red and everything in between, are now available.

There are two main types available:

The hybrid versions

Summer Red 4-5 m, Scarlet Red colour,
Summer Beauty 5-7 m, Pale Pink colour,
Summer Glory 5-7 m, Purple Pink colour,
Summer Snow 5-7 m, Cream colour.

To get these hybrid flowering gums, a breeder has crossed a Corymbia ficifolia (Red Flowering Gum) with its close relative Corymbia ptychocarpa (Swamp Bloodwood) to end up with a range of beautiful small trees.

With these hybrids, the flower size is slightly bigger than the straight Corymbia ficifolias. All need to be grafted to ensure they grow true to type and label.

Because they have tropical tree genes in them, they have proven to have better and stronger growth in more humid climates such as Northern NSW and Queensland.

The non-hybrid versions

Dwarf Orange 2-3 m, Fluoro Orange colour,
Calypso Queen 3-4 m, Watermelon colour,
Baby Scarlet 2-3 m, Scarlet Red colour,
Wild Fires 5-6 m, Fire Engine Red colour,
Lollypops 5-6 m, Powder Puff Pink colour,
Little Sweetie 5-6 m, Cerise Pink colour.

These non-hybrid varieties are generally selections based on normal seedling variation. Here collectors have found mature specimens that flower well, have good growth habit, size and colour, and have replicated them with grafting.

To produce large numbers, grafting is necessary to guarantee vigour, colour, form and size and that they grow true to label.

The rootstocks for all flowering gums are usually 'Bloodwood' or 'Spotted Gum'. Although these can grow into big trees, as rootstocks for these Flowering Gums they seem to be governed by the size of the tree/bush grafted onto them. The grafting of Eucalypts has been proven to reduce the mature size of the tree.

All of these trees but particularly the hybrid ones, are sensitive to severe frost if they are under five years old. After this they develop resistance as they mature, so some protection is advised if you are in a frost prone area.

The best time to buy them is in spring and plant out when all danger of frost is finished. This gives them time to get established and acclimatised before winter. For gardeners in colder areas, the worst time to buy them is in autumn if you intend to plant them out close to winter.

Along the NSW coast north of the Illawarra into southern Queensland, they can be planted almost any time except in winter. The non-hybrid Flowering Gums come from South West of Western Australia where there is little humidity, consequently they appreciate a temperate climate better than tropical or humid climates. The 'Summer' hybrid gums are ideal in these conditions.

When planting do not disturb the root ball, gently knock off pot and plant into a prepared hole. If the plant is old and potbound, some gentle teasing out of the lower roots may be required. Prune off any rootstock shoots you see growing from below the graft union (indicated by a change of bark colour).

The plants appreciate an annual prune after flowering before the gum nuts begin to form if you want exceptional flowering the next year. A dose of a native blend (low phosphorus) fertilizer in early spring will also ensure better flowering next season.

Other variations

Eucalypts in the bush can cross pollinate themselves and natural hybrids have been found, although nothing of great ornamental value seems to have been found yet.

Work has been done hybridising other small ornamental Eucalypt species in South Australia, but these are generally not suitable for growing on the east coast because of the humidity.

There will always be non-grafted Corymbia ficifolias available but you won't know what you have until they flower after about 5-7 years. You may even have grown one from seed yourself, but the same applies. One of these grown on may eventually turn out to be very good if you are lucky, but is more likely to be very ordinary or a dud when compared with the available grafted flowering gums.