Garden tips: curry-leaf tree; bamboo; shade trees; silver birch

A reader asks: We’ve removed 12 clumps of bamboo with a chainsaw, and poisoned it, but it keeps reshooting. What now?

It can take years of regular, persistent treatment to get rid of bamboo.

Readers’ gardening problems solved. This week: How to eradicate bamboo, what to do with curry seeds, new shade trees, and how to encourage silver birch.

We’ve recently removed 12 clumps of bamboo with a chainsaw. It keeps reshooting despite spraying with concentrated Zero. Digging it out is definitely a long, slow process. What’s the most effective method? - PAM SHOEBRIDGE, MALENY, QLD

Control with glyphosate (Roundup, Zero) is most effective in spring and summer. Cut stems to 20cm and immediately pour a 1:3 dilution down the hollow stems and over the cut surfaces. Spot spray leaf regrowth when young. Regular, persistent treatment across several years is necessary for eradication. Call a stump grinder to remove roots.

My curry-leaf trees have a profusion of seeds. How can I use them? - BO GIL, BRISBANE

Curry-leaf tree (Murraya koenigii) is not the source of curry powder but the leaves are used to flavour various spicy dishes. The black, shiny berries are edible, sweet when ripe, but have an aroma some find unpleasant. Do not eat the poisonous seeds. In northern parts of Australia be sure to remove the berries as this tree has potential to be weedy. The seeds germinate easily and birds love them.

Can you advise on suitable small to medium shade trees for the NSW mid-south coast, leaf-free in winter to help keep heating bills low? It’s a reasonably sheltered position about 1km from the sea. - GARY MILLER, BATEMAN’S BAY, NSW.

Crepe myrtles (Lagerstroemia) have four seasons of interest; check the Indian Summer series for a range of colours and sizes. Other choices include flowering ash (Fraxinus ornus), white cedar (Melia azedarach), one of the smaller ornamental pears (Pyrus ’Dancer’ and ’Edgewood’), mulberry, or box maple (Acer negundo ’Sensation’ or ’Edgewood’). Details about many of these are at flemings.com.au.

The silver birch seedling we planted five years ago has grown 3m tall, but during the past two years there has been little growth and only a smattering of leaves. Can it be saved or should we plant something else? - GABRIELLE SMITH, SYDNEY

Silver birch (Betula pendula) generally doesn’t do well in Sydney. It likes a cool, mountainous climate and soil. Tropical or river birch (Betula nigra) is much better. It has a similar shape and graceful form; like silver birch it looks best in small groves. Rather than silvery branches, it has reddish-brown bark that exfoliates in papery curls.

Send your questions to: [e-mail] or Helen Young, PO Box 3098, Willoughby North, NSW 2068. Website: helenyoung.com.au. The best question for February wins a vertical garden kit of 10 Multi-Hang pots, worth $69, from wallgarden.com.au. They’re a good size, versatile and Australian-made from BPA-free recycled plastics.

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