The Back Yard

Justin Newcombe's tips for creating a gorgeous and productive garden

Gardening: A pitiful passionfruit problem

By Justin Newcombe

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Landscape gardener and Life columnist Justin answers your questions.

Passionfruit like friable, free-draining, composted loam. Photo / Babiche Martens
Passionfruit like friable, free-draining, composted loam. Photo / Babiche Martens

Early this year I planted some passionfruit plants in a narrow strip of my yard and added potting mix and slow release fertiliser to the hard soil. My plants took off and climbed the trellis quite quickly and one piece of fruit had formed by May. Over winter all the vines yellowed and withered and appear to be dying, although a second piece of fruit is now almost ripe. About a month ago I read that passionfruit are acid-loving plants so gave them some Yates Thrive for azaleas and camellias, plus some slow release plant food. The tips of the vines are now greenish but overall there is very little foliage. When I moved to this house I was told that this section was a hotel carpark before the house was built about eight years ago. Do you have any advice?
- Daphne Field

It sounds like a classic case of poor-quality, compacted soil. Your place used to be a carpark and with modern construction methods, a hard compacted base (usually clay) is a bit of a prerequisite. Passionfruit would rather have a friable, free-draining, composted loam. The other thing I notice here is you have planted in a "narrow strip". passionfruit have shallow spreading root systems but your plant probably can't spread much.

The best thing you can do is mulch your plants with well composted chicken poo and straw. Even lawn clippings and cow poo. You need to build up the soil layer above the ground. I would also stop feeding with azalea food as this is a bit too acid. Try using Sequestrone Plant Tonic from Kings to give your vines an initial boost, but focus on the soil. The plants above the ground are simply a reflection of what's below it.

I noticed in your column of October 16 your suggestion to spray roses weekly with a garlic and baking soda spray. Could you please give me the quantities and method for making the spray using these ingredients. It sounds like a good organic spray.
- Beverley Golding

For every one litre of water use:

* Half a teaspoon of garden friendly soap (I use eco dish soap)

* 1 Tbsp olive oil (you can use horticultural oil from kings)

* 1 tsp baking soda

* Three or four cloves of crushed garlic

Let the garlic soak for a day or so in a jar with just enough water to cover it then add to the other ingredients. Check your plants 20 minutes after spraying. If they show signs of wilt then spray lightly with water. You will need to water down your mixture a bit and re-apply the following day. And remember, don't spray in the middle of the day.

We have quite of number of flax planted on our property, both native and red variety. Every one of them is covered in large rusty red/black measly spots. Do you know what would be the cause of this and how do I to fix the problem? The flax look quite healthy.
- Noelene

It sounds to me like mealy bugs. You'll find these at the base of the flax fronds, where they join the plant. Oil-based sprays work best so give Yates Conquer oil a go. Follow the safety instructions carefully. For a home-made remedy try olive oil and soap. This may be successful. It's also best to keep an open, airy canopy to encourage light and birds into the foliage where the pathogens are. Another flax infliction is caterpillar damage. Although you don't say the plants look eaten it's best to check anyway. Again keep an open airy canopy and remove all dead or badly damaged foliage. Caterpillars could be treated with derris dust but try squirting them with the hose first as they absolutely hate water.

Weekend checklist

* Plant, plant, plant - start getting your summer veges and flowers in the ground now, including sunflowers.

* Mulch your fruit trees and feed with sheep pellets.

* Check your irrigation for blocked heads and your hose for leaks.

* Deadhead flowers and keep beds clean to reduce pathogens.

* Keep a birdbath topped up near your bottlebrush or banksias.

* Sow beneficial insect blends around your fruit and vege garden.

* Spray your roses with Yates Bravo or try the spray (recipe in the article).

* Start making comfrey and seaweed sprays now.

* Plant your tomatoes but remember not to feed until they flower.

* Plant corn and underplant with pumpkin. The pumpkin will keep the ground moist while the corn will grow unobstructed.

* Plant basil by seed. Each pack has about 200 seeds and I've found them really easy to propagate. If you're keen it's easy to make loads of pesto which you can freeze.

* Set up beanpole structures for your kumara. This keeps the vines off the ground and helps your plants form massive tubers rather than loads of small ones.

* Grow your gherkins off the ground on tepees. This makes them easy to manage and harvest.

* It's not too late for strawberries. Stock up at Kings today.

* And need I remind you? Turn your compost.

For more gardening tips see kings.co.nz

* To ask Justin a question, click on the email link below.

- NZ Herald

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