In the garden 28/11/2008

  • Spring flowering shrubs are best pruned and then fed as they finish flowering, which, by definition, most will have done by now.
  • Stop putting off deadheading rhododendrons and get onto them asap.
  • Stay on top of weeds which are growing vigorously.
  • Scarlet runner beans can be planted. It is the last opportunity to get kumaras, yams and sweet potato variants into the ground. If you are still planting potatoes and tomatoes, they will be late crops so don’t delay on getting them in.
  • Keep successional sowings of peas, green beans, corn and all salad vegetables. These are all crops that need to be sown fortnightly to ensure continued supply.
  • Stop picking your asparagus immediately, no matter how great the temptation. They need the late shoots to build up strength in the crowns for next year.
  • Prune grapes, shortening the new growth to two leaves above the bunches and removing the enthusiastic lateral growths. This improves fruit yield considerably.
  • Brassicas are under siege now from white butterflies and other pests and diseases so unless you are prepared to spray, give up on trying to grow them (including rocket and mustard) until the cool of autumn descends.

Amongst life’s random and probably useless pieces of information is the news that the growing of the Giant Jersey cabbage has been in major decline over the past fifty years. This is clearly a terrible shame because not only are the leaves suitable for using in soup or feeding to cattle while the roots can be carved into thimbles. But the greatest use of the Giant Jersey cabbage (which has a proud history in the Channel Islands) is that it used to be cultivated for the production of gentlemen’s walking sticks. It did take three years to develop a stem worthy of a walking stick for a Victorian gentleman, but it sure beats cutting down a tree.

The Elements of Organic Gardening

Author: HRH The Prince of Wales with Stephanie Donaldson
Publisher: Orion distributed in NZ by Hachette Livre
ISBN 978 0 297 84498 3

No, HRH did not actually write this book and my review copy was not, alas, signed by him but he is a very keen gardener and has been committed to organic and sustainable gardening practices for many years, enduring quite a bit of ridicule before it became fashionable. This is a book for gardeners, not for fans of the royals (though the latter may enjoy it too). What sets this book apart from other organic tomes is that it is not solely dedicated to the production of healthy food. Indeed, while chapter 2 is on growing fruit and veg, much of the rest of the book is dedicated to good land management avoiding the use of chemicals with particular reference to maintaining a very high standard in ornamental gardens.

The Prince has three gardens – at Highgrove, Clarence House and Birkhall and he takes a hands on approach to managing all of them. Naturally he is backed up by very capable gardening staff but these gardens are his projects. The book is full of handy hints on gardening and quite a bit of very precise information. Some practices clearly require a generous royal budget (the water recycling process at Highgrove is reasonably complex) but many of the other tips and hints are within the reach of all gardeners. There is even a chapter on how to start converting to organic gardening practices. It is good to see a book which demystifies organics, avoids the hocus pocus fringe element often associated with it and which promotes practical solutions in sustainably managing high quality ornamental gardens on a large scale. Well done, Prince Charles.

I dream of hostas with a snail free leaf

Hostas have been preoccupying me for the past fortnight. First up, Mark and I volunteered to take a workshop on the topic during our recent festival and were a little taken aback at how many people turned up to hear our pearls of wisdom on the topic. And secondly, I have spent this week dividing and repotting hostas in the nursery. I have reached the point where I even dream about them which may be a sad commentary on the state of my life at the moment. But there are probably worse subjects to dream about than hostas.

When we used to sell plants by mail order, we were often surprised by the number of people who fail to understand that hostas are deciduous – in other words they disappear underground in autumn to re-emerge in all their glory in spring. And it is all that fresh spring growth which is their greatest appeal. That and their endearing tolerance of shaded conditions, even dry shade.

The worst example of hosta ignorance came from a new customer in Auckland. We despatched her order by courier in late autumn and she faxed back to say that the carton had arrived and all the plants were in excellent order, bar the hostas. I can still recall her words: “It appears there has been a rabbit in the carton eating the hosta foliage. Or if the hostas are meant to be like this, then I don’t want them.” I can not remember how we resolved the situation but I am pretty certain we never sent her another plant list. Some customers, as Mark has been known to observe, put the cuss into the word customer.

As with most other plant genus, hosta aficionados like to search out the new or the different (and in the hosta world, new does not always equal visibly different) so a full hosta collection can become rather large. But we are tending the other way and weeding out varieties which have minor variations at best. In fact I find it impossible to tell the difference between Patriot (itself a sport of Francee) and Minute Man. All three varieties are green with a white edge and googling hostas throws up a host of other minor variations of the same original plant. Hostas are not all stable in type and some varieties tend to throw up what are known as sports – aberrations or variations. Occasionally it will be something worth having but that is rare… The flip side of the coin is that the variegated hostas can tend to revert to a plain colour and that reverted part of the clump will often be stronger growing so will take over in time. So if you have a fancy hosta with a plain section, it pays to cut out that reversion. As most of the newer varieties in this country have come in as tissue cultured plantlets (in other words they have not been divided from an established clump but have been increased in a laboratory from cell divisions and grown on agar), the problem of reversions is becoming more common. Tissue culture is not always stable and can throw up variations or reversions.

The most common mistake made by less experienced gardeners is to be seduced by all the wacky variegations and to plant them together – the green with white edging, the reverse variegation of white with a green edging, the blue and yellow both ways and the green and gold options. After all, who wants to buy a plain coloured hosta, especially if it is plain green or a low key blue toned one? My rule of thumb is that every variegated hosta needs at least two plain coloured ones to set it off. So a showy big blue hosta with a yellow edging is going to look a great deal more effective if it is grouped with a small plain yellow and a mid sized plain blue plant. It is the variation in size, leaf shape and some level of restraint in combining patterned leaves which makes a hosta patch pleasing to the eye.

If you can’t bring yourself to buy plainer hostas and nobody is offering you divisions, raise seed. No matter what parent plant you collect the seed from, the vast majority of offspring will return to plain colours, mostly green.

Hostas are predominantly for shady areas of your garden. They are tolerant of very dry shade under trees but equally they will be happy in damper areas with heavy soils. What they don’t like are light soils in full sun – their foliage will just burn and the plants will fail to thrive. You can get away with reasonable light levels on the margins of sunny areas but the paler variegations (the plants with white or pale yellows) will burn and crisp around the edges in direct sun.

The greatest problem with growing good hostas, as every gardener knows, is slugs and snails which feed voraciously on the leaves. I spoke to many garden visitors, particularly from Auckland and Hamilton, who talked about walking out at night and crunching their way across snails and I can remember seeing the phenomenon once in Palmerston North where it was like a horror movie (The Invasion of the Snails, perhaps, or Snails’ Revenge) with literally hundreds of them teaming across a concrete pathway. If you have a snail problem of this magnitude, forget growing anything that is snail fodder. But if you have only a moderate issue with these herbivores, a combination of good selection and good management can keep the problem within manageable bounds. Choose hostas with thicker, tougher leaves rather than the soft and wispy types. Slimy crawlers do not appear to like slithering over gritty surfaces so circling plants with sand, sawdust, baker’s bran or similar will often deflect them elsewhere. We have little problem under our rimu trees with the thick carpet of rimu needles. Yes you can use slug bait, but it is not very nice stuff and can poison dogs, hedgehogs and birds so be very sparing – one bait per plant is all that is required. If you head out with a torch on a misty or rainy night after a dry period, you will often find the hungry offenders on the move.

Given that every discussion about hostas comes down to slug and snail control in the end, I leave you with the thought that most of the slugs in this country and all of our icky snails must have come in on plant material. What I do not understand is why, on those early boats bringing settlers to New Zealand along with all their trappings to remind them of home (blackbirds, thrushes, sparrows, trees and plants), they did not usefully employ themselves on the long sea voyage exercising digital control to ensure that not a single pesky slug or snail survived. It would have saved us a great deal of trouble in the garden.

November 21, 2008 Weekly Garden Guide

We are not great on growing annuals (my expensive packet of white cosmos seed failed to germinate), but if you use annuals for bedding, you will be wanting to get plants in now for a display when the family turn up for Christmas… If you can be bothered deadheading annuals, it greatly extends their display time because their instinct is to flower, set seed to ensure their continued survival and then die. So delaying the seeding stage forces them to put up more flowers.

  • Ornamental pots are remarkably cheap these days and a simple pot planted with annuals now can make a charming gift for Christmas Day – a good gift for widowed aunts or people who like flowers but do not garden much. If you want to do it well, buy a potting mix with a quick release fertiliser added, pop in the baby plants and keep watered and disbudded so the plants grow to fill the pot before you let them set flower buds a couple of weeks out from Christmas.
  • Wisterias can be rampant growers and are putting on their spring growth in a bid for world domination. Cut back the long, waving shoots to more manageable proportions – three or four leaf buds out from the branch is all they need. It is the same principle with apple trees which need an early summer prune as soon as the growths sprint away.
  • From here on, the ornamental garden is more about summer maintenance – pruning, shaping, mulching and staying on top of weeds. There is a limit to how much creative work and planting you can do over the summer months.
  • But it is all go in the vegetable garden where you should be sowing and planting successional crops of all the staples – corn, peas, beans and salad vegetables. Main crop potatoes, kumara, pumpkins and other cucurbits can all be planted. Watch out for pests such as whitefly, aphids, leaf roller caterpillars and the like. Early vigilance can hold them at bay and prevent major problems developing.
  • Queen wasps are still on the wing, building up their nests. Mark can be seen out with pyrethrum spray stalking both the queen wasps and the narcissi fly. Getting rid of the queens now holds wasp infestations at bay.
  • The one lawn weed worth spraying for is prickly Onehunga weed which makes it impossible to walk barefooted. We should have reminded you earlier to do it – if you have a problem with it, ask at your local garden centre for advice on which spray is currently recommended and permitted and make it a priority.

And a quote from Anon this week: God made rainy days so gardeners could get the housework done.

One Magic Square

Author: Lolo Houbein
Publisher: (Wakefield Press)
ISBN 978 1 86254 764 3 (pbk)

The whole principle of this book is that you can grow your own food on one square metre of garden. “My goodness,” said a friend. “If your garden is only one square metre, you could take it on holiday with you.”

If you are only going to have a garden which measures one metre by one metre, it is a bit of a moot point as to whether you need a book which runs to about 350 pages to tell you how to do it. Yes there are planting diagrams. There is the soup plot. There is the Aztec Plot (that is the one with a marigold in the centre). Then there is the plan for the pasta/pizza plot. How about the curry plot? Maybe you fancy the stir fry plot or the anti-oxidant plot.

If you have the gardening skills to work to this level, odds on you will want to expand beyond one square metre. There is quite a bit of additional information (but nothing that I have not seen before in other how-to guides) and it is written by a woman who is clearly enthusiastic about her topic and has a love of home grown vegetables. But honestly, I need a lot of convincing that it is possible to achieve self sufficiency and stave off famine on a mere square metre of vegetable garden. This book may appeal more to eccentrics rather than the target audience of novices.