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PLASTIC BAGS Should I be composting tea bags and using the compost on the vege patch? I read that tea bags contain plastic but the worms do such a good job of turning them into compost that I am loath to dispose of them in any other way.

MARIE KILGOUR, GOLDEN BAY

ASome tea bags do indeed contain small amounts of plastic and some have non-compostable metal staples too.

The older style of pyramidshaped shiny tea bags may be made with polyethylene terephthalate (PET) but manufacturers are responding to public awareness of microplastics in the environment by changing to materials made of maize starch treated with an enzyme that has plastic-like qualities and can be spun into fibres. Although this compound, polylactic acid (PLA), is plant-based, it needs the high temperatures generated in a commercial-scale compost system to break it down rather than a home gardener’s bin.

Even flat, tagless paper tea bags that look completely compostable are heat-sealed with a thin film of polypropylene holding the top and bottom together.

Check the website of your favourite brands of tea to find out what their tea bags are made of and if the materials are compostable.

If you are concerned about adding these materials to your compost heap, rip the bags open, compost the tea leaves and dispose of the bags in the rubbish.

Alternatively, make the change back to loose-leaf tea. It’s often cheaper and of better quality than the dusty stuff found in tea bags.

To make single cups of tea, invest in a tea ball infuser or two – there are many cute and functional designs available.

Or rescue grandma’s teapot from the back of the china cabinet and turn morning and afternoon tea into an occasion.

Barbara Smith

STAGHORN FERN I planted this fern in a bucket about 25 years ago and it’s now about 1m high. I’d hate to lose it. Do need to do anything to it?

KAREN MEAD, AUCKLAND

AStaghorn ferns grow naturally as epiphytes in the bush canopy. They collect moisture from the air and nutrients from debris caught in their fronds rather than using their roots as other plants do.

This means staghorns need minimal care in the garden as long as they are placed where conditions are similar to their bush home. The best position for staghorns is in dappled shade. As epiphytes, staghorns need perfect drainage. They are fairly drought tolerant but shouldn’t be allowed to completely dry out. Don’t overfeed staghorns

– a few sheep pellets among the fronds a couple of times a year or half-strength liquid plant food every three or four weeks is plenty.

Plants can be attached to trees in the garden but large specimens may damage the host tree so staghorns are often grown on a section of punga log or other backing material.

As insurance against losing your plant, you could start a new one. Remove one of the pups (offshoots) growing on the outer layers of the mother plant. Put a lump of soaked sphagnum moss on a tree trunk, piece of wood or punga log. Place the staghorn pup on top. Tie in place with an old stocking or make a hammock from a piece of chicken wire stapled to the mount. The pup will soon grow over the wire or stocking and hold itself in place. Barbara Smith

PAST BLOOMING? Do begonias have a lifespan? My favourite is over 20 years old. I split it but the flowers were very small and disappointing this year.

SANDRA BOSTOCK, HAWKE’S BAY

AWow, you have obviously been doing a very good job looking after your precious begonias as 20 years is way past their use-by date. Most begonia tubers are at their peak around three to five years old. Beyond that the flowers will get smaller and the plant will weaken.

I suspect that your long-lived begonia is a basket type with Begonia boliviensis in its genetic makeup because this species tends to pass on longevity and larger tubers.

I recommend that you take a basal cutting or two in spring so that you always have vigorous, healthy replacement plants. I never recommend dividing a tuber because the site where the division or cut is made will never grow roots or shoots, further weakening the plant apart from the very real risk of letting rot into the tuber.

Here’s how take a basal cutting. When the tuber starts into life, select one of the growths coming off the tuber (pictured above) when it is about 75mm. Wiggle it gently back and forth as if you were breaking a piece of wire and it will come away from the tuber, sometimes with small roots attached. Dip the end into some growth hormone like Clonex and plant into a gritty or sandy mix. Within a month you will have a new plant.

The Auckland Begonia Circle has members in the Hawke’s Bay who would give you specialist help. Graham Milne, aucklandbegoniacircle.org.nz

PLANTS ON FIRE? Trees in my coastal garden in salty, sandy, dry soil look burnt with dead black leaves. Neem granules haven’t worked. What’s going on?

ERICA BROUARD, CHRISTCHURCH

AThere are several factors at play here. The symptoms indicate that root fungal disease is possible but as the plants are growing in sandy soil close to the seaside, the likelihood of this is low.

There is certainly attack by chewing insects. The nature of the damage and open sandy situation, suggests this is a beetle or weevil (adults of soilliving grubs which love sandy soils). These beetle or weevil adults are rarely seen because they are mostly nocturnal feeders and are only around for a short time during mating flights.

The die-back and blackening is caused by dry conditions, exacerbated by grubs feeding on the roots, plus scale insects on stems or leaves sucking sap. You may find grubs around the roots. Grubs with legs are the larvae of grass grub, black or bronze beetle. Grubs without legs are larvae of weevils. If these larvae are present, they will probably be found in grassed areas nearby as well.

The only effective treatment for larvae in the soil is Kiwicare Lawnpro Protect or Yates Mavrik watered in well. There is no organic treatment.

For scale, spray twice, 10 days apart with Grosafe Enspray 99 plus Naturally Neem. These two organic insecticides work well together – Enspray by smothering all stages of sucking insects, complemented by the anti-feeding and disrupting action of Naturally Neem.

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