Cultivation notes
General comments
All the comments are based on published information and Prima Bio's experience. However, all purchasers should recognise that there is little history of growing any of these subjects in the UK, either outdoors or under cover, for more than two years. Thus, satisfactory longer-term growth or flowering cannot be guaranteed. Prima Bio accepts no responsibility for the subsequent performance of any plants purchased.
All Prima Bio's plants are raised in pots containing a mixture of ericaceous compost and perlite. This provides a free-draining compost that appears to be suitable for all species. Plants in large pots have coarse bark in the base of the pots, to facilitate drainage. Provided the pots never stand in water, all species described below seem to thrive on frequent watering during the growing season, even though they would normally experience dry conditions in summer. Watering from above with hard water seems to cause no problems. Watering from below (e.g. on a sandbed) has not been tried.
All species greatly benefit from regular liquid feeding with a balanced formulation in the growing season. They also require regular potting on if they are to be maintained in pots. In contrast to some other groups of Australian plants, none of the subjects appears to resent phosphate in fertilisers.
The species offered for 2005 are all from climates that are very warm and sunny in summer, and bright and mild in winter. In the UK, it is likely that they will benefit from some shelter, and dislike exposure. They also dislike prolonged exposure to still, moist air such as is frequently found in greenhouses in winter. Provided there is no frost, the frost-tender species generally appear happier in a bright but sheltered spot outdoors in winter.
Performance in conservatories that are heated in winter has not been examined, but merits examination provided the plants are given maximum light and minimal watering.
Eucalyptus caesia
A shrub or small tree grown in Australia primarily for its striking red flowers. It tends to have a very straggly growth habit. It appears very tolerant of the UK climate, and is largely free of pests and diseases although aphids occasionally colonise the shoot tips. It tolerates mild frosts well. Probably not suited for growing in containers. However, it thrives best when given plenty of heat and sun - plants in the ground in a polytunnel at East Malling are very vigorous. A plant in a greenhouse bed at Lullingstone produced flower buds this summer.
Eucalyptus erythrocorys
This is a mallee species from Western Australia which is quite widely-grown in Mediterranean climates. Its flower buds have striking red caps (opercula), and the flowers are large and bright yellow. It is not frost tolerant, at least when young. However, it is recognised as suitable for growing in large containers. A Prima Bio specimen aged 18 months and now in a 15 litre pot initiated the characteristic flower buds in July 2005. This specimen has been kept outdoors except for the mid-winter period, when it was kept in a cool but frost-free greenhouse. Seemingly a species free of pests and diseases, even when under cover.
Eucalyptus macrocarpa
A straggly mallee species from a dry part of Western Australia. It has glaucous-grey leathery leaves and large scarlet flowers - the largest of any eucalypt. It appears surprisingly easy to grow in the UK, provided the foliage is kept dry and plants are in a well-ventilated location in winter. Even young plants tolerated frosts down to -5°C under these conditions. Reasonably free of pests and diseases although sap-feeding insects can colonise shoot tips. Longer-term potential unclear. Probably a species for enthusiasts who like challenges.
Eucalyptus preissiana
A small mallee from the south coast of Western Australia, which has large yellow flowers and distinctive woody bell-shaped seed capsules. A popular ornamental in Mediterranean climates worldwide. It has a bushy habit and large leathery leaves. It is remarkably free of pests and diseases. Easy to grow, and said to be suited to growing in large containers. Tolerant of mild frosts but probably best overwintered in a frost-free greenhouse. Another species whose potential in the UK is unclear at present.
Eucalyptus polyanthemos
A slow-growing but potentially large tree from inland parts of New South Wales. Most commonly cultivated as regularly-pruned plants to provide a supply of the distinctive juvenile foliage, which is used in floristry but would also be an interesting feature in a garden. The shape and colour of this foliage varies considerably between individual plants, but the leaves are always held on slender but tough petioles and stems. Prima Bio's plants are from two high elevation provenances that are likely to have greatest cold tolerance, and survived -7°C on an exposed site in Kent in March 2005 with only slight damage. However, the species is probably most suited to being grown outdoors in sheltered but sunny sites.