Dead animals as fertiliser; lemons; soursobs; fast-growing trees

Dead animal carcasses can help give your trees and garden a boost.

Trees such as river red gums thrive if planted with a dead animal.

Living on a farm, I’ve experimented with burying unexpected carcasses and planting tree seedlings on top. One river red gum grew 5m in three years. Is the carcass responsible for the remarkable growth? What would they have absorbed?

JOHN GRIFFIN, BY EMAIL

Blood and bone is an ancient fertiliser, supplying nitrogen and phosphorus in a slow-release form. Interestingly, Eucalyptus camaldulensis responds well to phosphorus. Some wonderful country gardeners favour this method of establishing trees. Traditionally, passionfruit vines were planted with a liver beneath to supply additional nutrients.

When can I transplant a small lemon tree that arose from birds dropping seeds from lemons they attacked? What are some tips for citrus care?

JENNIFER FOONG, BY EMAIL

Early spring is good for transplanting unless in a frosty area. But a seedling-grown lemon may not be the same as the parent tree. It’s better to buy a known variety, grafted on to superior rootstock. Eureka is a good all-rounder, cropping most of the year. Citrus needs full sun, good drainage and enriched soil. Fertilise lightly and often with an organic-based citrus fertiliser and keep evenly watered. PestOil or Eco-Oil will control most citrus pests.

Is there anything that will kill soursobs once and for all (and doesn’t require hours of picking bulbs out of soil)? I feel like I’ve tried it all.

SACHA PECH, ADELAIDE

Timing and persistence are key to eradicate this bulbous oxalis weed. Strike as the plants produce their yellow flowers in late winter, when the bulbs’ food store is used up and before new bulbils form. Paint the leaves with glyphosate (Roundup, Zero), taking care not to touch other plants; Roundup Gel is useful. Repeat in subsequent years, when the problem should steadily lessen.

My daughter has just had a baby and moved to a new property with a large back yard. Can you recommend a quick-growing tree that children would love to climb?

SUE MCDONOUGH, BENDIGO

Deciduous trees are cold tolerant and let in winter sun. For autumn colour, look at the maples Acer ‘Pacific Sunset’ or Acer negundo ‘Sensation’, and ornamental pear, Pyrus calleryana ‘Aristocrat’, with its superior branching structure. Chinese weeping elm (Ulmus parvifolia) has ornamental bark and a spreading canopy; ‘Todd’ is an improved form. Flemings.com.au has excellent photos and information.

Send your questions to: [e-mail] or Helen Young, PO Box 3098, Willoughby North, NSW 2068. helenyoung.com.au.

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FLORA

You may have seen guarana listed as the hero ingredient in energy-boosting soft drinks and wondered what it is. The woody vine or climbing shrub Paullinia cupana is native to the tropical Amazon Basin and bears dense clusters of fleshy, red berries.

When ripe they split to reveal their black seeds and white flesh, looking disconcertingly like eyeballs. The crushed seeds are used for their significant caffeine content, twice as high as coffee beans, to impart a stimulatory effect.

Local native tribes make a paste with the dried, roasted and powdered seeds, using it in drinks, foods and medicines. It’s not one to try growing yourself, unless you have a climate like the Amazon and extremely acidic soil. Seeds lose viability within three days of harvesting.