Yellow Gum, Johnston's gum
Eucalyptus johnstonii

Family: Myrtaceae

What it is like

Eucalyptus johnstonii is an evergreen Tree growing to 60 m (196ft 10in) at a fast rate. See above for USDA hardiness. It is hardy to UK zone 8. It is in leaf all year. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees. It is noted for attracting wildlife. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils, prefers well-drained soil and can grow in nutritionally poor soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry moist or wet soil and can tolerate drought. The plant can tolerate maritime exposure.

Height (m): 60

Where it is found

Usually found on badly drained sandstones from 600 - 2600 metres.

Australia - Tasmania.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 0

Medicine

Rating: 0

Other

Rating:

Tolerates maritime exposure, though the foliage may be burnt, and it can be grown as a shelter belt tree. Wood is of high quality.

Shelterbelt: Wind resistant plants than can be grown to provide shelter in the garden etc.

Wood: A list of the trees and shrubs that are noted for having useful wood.

Attracts Wildlife: Plants noted for attracting wildlife

Food Forest: Plants for Edible Forest Gardens and Food Forests.

How it is grown

Prefers a sunny position in a moderately fertile well-drained moisture retentive circum-neutral soil. Dislikes clay or chalk soils but succeeds in most other soils. Tolerates poor soils, especially those low in mineral elements. Tolerates dry soils and also drought once it is established. Tolerates maritime exposure, though the foliage may be burnt. A fairly hardy species, it tolerates long periods down to -6°c and short periods down to -9°c. Plants are hardy to between -15°c and -20°c according to another report. Eucalyptus species have not adopted a deciduous habit and continue to grow until it is too cold for them to do so. This makes them more susceptible to damage from sudden cold snaps. If temperature fluctuations are more gradual, as in a woodland for example, the plants have the opportunity to stop growing and become dormant, thus making them more cold resistant. A deep mulch around the roots to prevent the soil from freezing also helps the trees to survive cold conditions. The members of this genus are remarkably adaptable however, there can be a dramatic increase in the hardiness of subsequent generations from the seed of survivors growing in temperate zones. Eucalyptus monocultures are an environmental disaster, they are voracious, allelopathic and encourage the worst possible attitudes to land use and conservation. This species is sometimes included as a sub-species of E. vernicosa. Plants are shallow-rooting and, especially in windy areas, should be planted out into their permanent positions when small to ensure that they do not suffer from wind-rock. They strongly resent root disturbance and should be container grown before planting out into their permanent position. The flowers are rich in nectar and are a good bee crop.

Propagating it: Seed - surface sow February/March in a sunny position in a greenhouse. Species that come from high altitudes appreciate 6 - 8 weeks cold stratification at 2°c. Pot up the seedlings into individual pots as soon as the second set of seed leaves has developed, if left longer than this they might not move well. Plant out into their permanent positions in early summer and give them some protection from the cold in their first winter. The seed can also be sown in June, the young trees being planted in their final positions in late spring of the following year. The seed has a long viability.

Best place to grow: Woodland Garden Canopy; Bog Garden;

Habit: Tree

Hardiness: 7-10

Growth: Fast

Soil: Light (sandy), medium, heavy (clay)

Shade: No shade

Moisture: Dry, moist, wet

Things to keep in mind

Citronellal, an essential oil found in most Eucalyptus species is reported to be mutagenic when used in isolation. In large doses, oil of eucalyptus, like so many essential oils has caused fatalities from intestinal irritation. Death is reported from ingestion of 4 - 24 ml of essential oils, but recoveries are also reported for the same amount. Symptoms include gastroenteric burning and irritation, nausea, vomiting, diarrhoea, oxygen deficiency, weakness, dizziness, stupor, difficult respiration, delirium, paralysis, convulsions, and death, usually due to respiratory failure.

Its other names

Local names

Synonyms

E. muelleri. T.B.Moore. E. subcrenulata