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YOUR GARDENING QUESTIONS THIS MONTH

Your questions answered.

QPOTTED FIG TREE I have a ‘Black Turkey’ fig tree that’s been in a large egg jar for five years. This year there was an abundant crop of large figs. The tree is thoroughly root bound and I can’t dig it out. How long can I expect it to last in this pot? Can I keep it alive and healthy with chemicals?

AA tree in a pot is really a giant bonsai. If it is left root bound, the crop will eventually start to diminish and the overall health reduce as the tree thinks it has passed maturity. But figs trees can live for over a hundred years, are very robust and they can handle being tortured better than most. The problem with bound roots is a lack of available nutrients and water – the less soil there is the less holding capacity for both. So feed it anyway you can – regular small doses of chemical fertiliser (you can’t sustain an organic ecosystem in an overcrowded pot), topping up the soil level with sheep pellets and including a liquid fertiliser with every water. You are basically going towards a more hydroponic type of management, so it is important to keep the moisture levels up and to feed a little and often. You can “burn” the roots with sudden doses of chemicals, so start small and build up to the high end of the recommended dosage over a month, then ensure you maintain this level regularly, even in winter when raining. Well cared for, it may go on cropping for years yet.

If you see the slightest sign of decline, start a new cutting as a replacement or re-pot it which may mean the end of your lovely pot as you are going to have to get it out of there somehow. To do that, remove it in winter, and tease out and loosen one third of the root ball. Replant using the best potting mix you can source with some slow release fertiliser such as sheep pellets and prune the canopy by roughly a third. Do this every year, taking three years to rejuvenate the entire root ball. Sheryn Dean

YVONNE MCDIARMID, AUCKLAND

What about star jasmine? It grows well in shade and can easily be trimmed for shape and size. In my garden, it flowers outside my bedroom window from late November through December and the scent brings a heady tropical atmosphere to summer evenings.

Star jasmine is evergreen and makes a dense screen which would be handy if you need to block neighbouring windows or need shade. It is one of the few climbers that doesn’t get “bare ankles” but has leaves right down to ground level.

Plants in pots always need more care than those in the ground. Use as big a pot as you can and keep evenly watered. Fertilise with a general slow release pellet fertiliser and liquid feed regularly.

Or try a pretty honeysuckle. Not the weedy Japanese honeysuckle but a tame ornamental one, Lonicera splendida, which are available from garden centres.

They are less vigorous than star jasmine and grow well in pots. They flower for a much longer period of the year but are semi-evergreen and can look a bit scraggly over winter. Plants can get bare at the base with all the flowers and leaves at the very top unless you regularly pinch back the growing tips to encourage the plant to branch out. They flower more prolifically in sun but do grow in shade as well.

Barbara Smith

ASANDRA HALLING, OREWA

This lovely evergreen shrub or small tree from Africa is called Alberta magna. Also known as the Natal flame tree, it’s not to be confused with the weedy Erythrina x sykesii (also commonly called the flame tree) which is on the banned plants list for Northland.

It tolerates light frosts but prefers warm, moist but well-drained conditions or sheltered coastal gardens. The glossy, leathery leaves are evergreen and the flowers and bracts give a colourful long-lasting display. It’s a favourite nectar tree for birds and monarch butterflies.

The bark on the trunk of larger trees looks like wrinkly grey elephant skin. In its homeland, this tree is in fact endangered because the bark is harvested for traditional medicines.

I asked Peter Cave (Peter Cave Nursery) for advice about growing the seeds. He says, “It’s not easy to grow from seed or cuttings, but if you don’t try you definitely won’t grow one!”

This advice is from the South African National Biodiversity Institute: Seed viability is variable so plant seeds densely in a porous but absorbent mix of river sand, bark and vermiculite. Scarification (grazing or penetrating) the seed coat aids germination.

Seedlings have a long juvenile period and should not be transplanted until well developed. Alberta magna is slow-growing but plants do flower while still small. Barbara Smith

ADEBBIE JOY YOI, GREYTOWN

Your photos show typical symptoms of buxus blight caused by Cylindrocladium buxicola or variations of this.

This disease is aggressive and difficult to eliminate once established. It usually arrives in a garden as an infection on purchased plants, not necessarily visible at the time.

It is best to hold newly purchased plants in quarantine for three weeks before planting to make sure they are free of the disease. It is also spread by wind, water, insect vectors and birds. It is harboured in fallen leaves and on the soil surface for long periods. Ongoing hygiene is important – remove infected tissue immediately and destroy. Clean secateurs and hedge shears before and after trimming, which must be done on a dry day.

The most effective fungicides are not available in the home garden range in New Zealand. The best we have is Grosafe Buxus Blight Fighter based on phosphite or Kiwicare Buxus Bight Buster based on fosetyl-aluminium.

According to RHS research, these products are only average. It will be necessary to use all the above cultural methods of prevention as well as the fungicide.

In situations where the disease is bad, it would be better to replace the buxus with an alternative small, low-growing hedge.

Bill Brett, Garden Pest & Disease Control, gardenpestcontrol.co.nz

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