Twig: Female pawpaw plants produce the best fruit

Q&A with our gardening guru. This week: pawpaws, jasmine and preparing lawn for winter.

Female pawpaws produce the best fruit; one male plant can pollinate several females.

I’ve planted out two pawpaw seedlings that sprouted in my compost. I know I need a male and female; how long before they flower to identify if I’ve chosen a pair? - Lissa Fry, Brisbane

Outside the tropics, pawpaws usually have separate male and female plants, but they can be bisexual or even change the sex of their flowers. Females produce the best fruit; one male plant can pollinate several females. Common practice is to plant many seedlings together and cut down all but one male once flowering, usually in the second year, identifies them. Female flowers are large and plump on short stalks; males are smaller, in clusters on longer stalks.

How do I get rid of sooty mould on my jasmine? - Ailsa Toneman, Perth

Sooty mould is a secondary problem. It’s a fungus that grows on the sticky honeydew exuded by sap­-sucking insects such as scale or aphids, covering leaves with unsightly black material. Treat the pests by thorough spraying with Eco­Oil or PestOil, or use Defender MaxGuard if you need something systemic. The sooty mould eventually washes or flakes off; you can speed that process by spraying over with Natrasoap.

My lawn has suffered over summer and is patchy and dry. How can I prepare it for the colder months? - Emma Puszkar, Tasmania

Autumn is a great time to fertilise lawns anywhere in Australia, strengthening and greening them before winter. To rejuvenate yours, first break up areas of compaction with a garden fork or hire a lawn corer. Rake out thatch build-up with a stout steel rake. Apply a hose­-on soil-wetting agent to help water penetrate and hold, then fertilise. You could also oversow bare patches with lawn seed or lay rolls of turf in bare areas.

How should I prune my grafted Eremophila? After two years it’s too big and leggy. There are shoots in the centre — can I prune back to these, reducing it to 60cm? When is best? - Ian Booth, Brisbane

Native emu bush prefers dry summer regions so grafted plants are a good choice for those in wetter locations. They are actually grafted on to rootstock of a different species, Myoporum. Excellent drainage and ample sun are essential. The recommended pruning regimen is to cut back by a third after flowering. It is safe to prune hard if there are existing shoots to prune to, and you can do it now.

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

The best question for April wins a Bokashi kitchen composting kit, worth $90 from Biome Eco Stores (biome.com.au).

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