February 15, 2008 Weekly Garden Guide

The rains this week were timely, even though there has not been sufficient to bring moisture levels back up to normal. But as far as container plants and the vegetable garden go, it is more efficient use of water to keep those levels up now rather than to let it all become bone dry again and then start watering. A little often is much better than a lot occasionally.

  • If you feel you must and haven’t yet done so, spray for thrips on rhododendrons – those nasty leaf sucking critters that turn the leaves silver and weaken the plant. An insecticide is required – ask at your local garden centre which ones are recommended for home gardeners. But unless it is a pretty special variety, we advocate avoiding spraying. Open up around the plant to allow more light and air movement. If the plant is really suffering, dig it out and replace it with a healthier option. Not all rhododendrons get thrips and some get them much worse than others.
  • The same can said for roses. If you want to avoid the need to spray, take a critical look now at which ones in your garden look good and which ones don’t justify their place. I am afraid Burgundy Iceberg is destined for the burning heap here whereas all the Flower Carpets, the rugosas, Sparkler (white) and a few others whose names I need to locate again are still looking just fine.
  • Our onion crop is non existent this year (after a brilliant harvest last year) but others who are more successful will be harvesting them as the tops die down. Onions need a cool, well ventilated situation to store well.
  • We are at least picking green beans but sadly the heritage variety, Borlotto Fire Tongue, does not cut the mustard. Heritage may equal old and unmodified but does not necessarily equal tasty and tender. These are stringy darned things that we won’t be growing again. The modern varieties are cropping better and taste better.
  • At least the rain this week makes it easier to start planting some winter vegetables, especially those varieties started from seed – brassicas (except brussel sprouts – too late now), carrots, spinach, silver beet and salad veg.
  • Keep melons watered well. Watch out for aphids and white butterfly, especially on brassicas.

February 8, 2008 Weekly Garden Guide

With no rain forecast yet and the need to conserve water, there is not a whole lot most of us can be doing in the garden. We don’t expect this sort of extended dry spell in Taranaki but other parts of the country cope with it most years. And at least the autumn rains will come in due course, unlike large parts of Australia who have no such prospect.

  • So a reminder that moving container plants to shaded areas or plunging them in the garden will reduce their need for water. If the water flows out the bottom of the pot as fast as you pour it in the top, it means you are wasting water because the mix is so dry that the water is running straight through and not being absorbed. Using a surfactant will help water absorption. A squirt of liquid detergent will also work.
  • Watering in the evening or early morning will mean that more water is absorbed. Rather than leaving a hose in one place to give a deep soak, repeatedly passing over an area with a fine spray (in other words, copying the action of banned sprinklers or emulating a light rain) will do more to soak an area and direct the water to where it is most needed. It takes longer but if you do it properly, you won’t have to do it so often.
  • Do not forget to keep an eye on the water level in the goldfish pond. If the level drops too much and the water heats up, it is not good for the fish.
  • Many of the spring bulbs are starting to move already and as soon as the rains come, they will all bolt in to growth. You can tell when they are starting to grow by the fresh white root which forms. So do not delay on digging up overcrowded patches that you may have earmarked for attention last spring. By far the largest proportion of our bulbs in this country are South African in origin, particularly those whose growth is triggered by autumn rains.
  • Spray citrus trees with summer strength copper and oil for mites. This also helps protect against botrytis which can strike later on and makes the leaves turn brown and cause the fruit to fall off.
  • A further reminder to prune flowering cherry trees now. We will admit that Mark still has to do ours. Remove witches brooms (the patches of dense foliage which look different to the main part of the tree – these will never flower and tend to take over) and shape the trees as required.
  • An update on monarch butterflies – if you have run out of swan plants, bigger caterpillars at least will eat pumpkin and pupate. Their golden excrement has a certain novelty value and is an indicator that they are happily digesting the pumpkin. It does not appear that you can raise young caterpillars entirely on pumpkin.

In praise of monarchs

The monarch caterpillars have been contributing to the stress in our lives recently. While our backs were turned, they stripped the plants in vegetable garden to the point where not a single leaf remained and then they started the exodus in search of more plants. I knew this had happened because I came across some intrepid souls in the middle of the driveway heading off to goodness knows where. As the nearest plants were in Mark’s terrace gardens a good 100 metres away, I didn’t like their chances of finding them so I had to do a manual transfer.

In preparation for the late autumn famine and in an attempt to get sufficient population wintering over, Mark sowed fifty metres of swan plants in a nursery block across the road. As these plants are only about 10cm high and already sporting eggs and baby caterpillars, he has regretfully come to the conclusion that he will need to practice some infanticide in order to allow these plants to grow sufficiently to achieve their purpose. The culling now will allow the survival for the greater good of later generations of caterpillars.

New Zealand is sadly lacking in a range of spectacular butterflies enjoyed in many other countries of the world. We have some beautifully marked moths but you need an eye for detail and an appreciation of understatement to perceive the beauty in moths. In the butterfly stakes, the miserable and unwanted cabbage white probably rules supreme in numbers. Red and yellow admirals are extremely rare around here but then so is their preferred host food of stinging nettles. The common copper doesn’t quite rank up with the admirals and monarchs.

In common parlance, a species indigenous to New Zealand includes those that arrive without assistance (this means that coconut palms up north are native now because there are instances where they have washed ashore and taken root). So I guess whether monarchs might now be regarded as natives here depends on whether the first butterflies were perhaps blown over from Australia, or whether somebody introduced them. But they do not, as far as I know, have any negative impact here and only enhance our visual environment.

Butterflies do on occasion blow over from Australia and are not unknown on the north coast of Taranaki. Our elder daughter spotted the lesser wanderer caterpillars on her grandmother’s swan plants at Urenui when she was very young. They were the usual black and yellow caterpillar but smaller and with an extra set of antennae. They morphed into a small monarch type of butterfly with slightly different markings but failed to naturalise despite our best efforts. The large and spectacular blue moon butterfly arrived tattered and exhausted after its long trans Tasman flight and despite Mark’s attentions, it failed to reproduce before it died. It would have been a showy addition to the summer garden.

So all we have in the showy butterfly line is the monarchs and they need some care and attention to their food source to flourish. I read a letter in the Weekend Gardener from a woman who works on three established plants. She nets two to prevent butterflies from laying eggs on them and restricts the caterpillars to one plant at a time. We can’t quite work out how she stops the caterpillars themselves from migrating to the two netted plants. Monarch caterpillars seem perfectly capable of finding swan plants even some distance away but this system seems to work for her. With plenty of space and having saved seed, Mark is more of the overkill type where he hopes his 50 metre planting will ensure continued food supplies.

The bottom line is that monarchs really only like swan plants (asclepias), or milkweed as it is sometimes referred to overseas. The term swan plant comes because of the seed head which is shaped like a swan and full of white fluff which enables the little black seed to become windborne and disperse more widely when the seed pod bursts. Desperately starving mature caterpillars will apparently eat pumpkin or melon flesh to stay alive and chrysalis but I have never heard of anyone successfully raising monarchs from egg to butterfly on anything other than swan plants.

Fortunately swan plants are very easy to grow from seed and if you can keep your swan plant from being decimated during the season, it will flower and seed freely. We had a truck in collecting plants here this week and we noticed it had a load of swan plants destined for a garden centre so if you want to buy one to get you started, ring around and see who has them in stock. Just be warned that if you buy a plant, you will need to keep it netted until it gets established or you will find that a stray butterfly will find it and lay its eggs while you are not looking.

Raising monarch caterpillars is loads of fun, unless you have the distressing experience of running completely out of food for them, and I am of the view that it is mandatory for parents and grand parents to introduce children to the delights of the life cycle of the monarch. Later in the season, Mark starts a hospital where he saves chrysalis which are in danger because they have been spun in inappropriate locations (at times some caterpillars are unwise enough to metamorphose on the swan plant where their brothers and sisters then eat the supporting stem, or on nearby plants which may not last long enough for them to hatch). The chrysalis need to hang in order to develop and hatch cleanly so he used to tie a fine cotton thread to the tip but has now graduated to the faster but less aesthetic masking tape, hanging them from a safer place. He does not get 100% success rate from this intervention, but the row of chrysalis hanging from a bar in front of one of our windows keeps us mildly entertained.

We have had occasional years when we have had good numbers of monarch butterflies wintering over in our garden and it is a joy and delight to see them stretching their wings together on a sunny winter’s day. They tend to congregate in one spot over winter. But every year we manage to keep at least a few resident around here to start us off again for spring.

If you want to know more about monarchs, there is the Monarch Butterfly NZ Trust whom you will find at www.monarch.org.nz

On another topic entirely, Mark has a yen to own a Planet Junior, a manual tilling device from way back, decades ago. If anybody has an unwanted Planet Junior in a back shed, he would be really pleased to hear from you. My attempts to locate him one on Trade Me have failed so far. We could promise said PJ a good and appreciative home.

February 1, 2008 Weekly Garden Guide

Today may herald the start of a new month but until some rain comes, there is not a great deal to be done in the garden. Central and South Taranaki gardeners in particular are under complete watering restrictions now and that is unlikely to change for several more weeks. Set priorities for what water you can use. Moving all container plants to shady spots will substantially reduce their need for water as will burying terracotta pots below the soil surface (plunging). You can recycle dish water, shower water or the rinse cycle of the washing machine.

  • While container plants can die from dryness and heat and so can recently planted material, established trees and shrubs may wilt and get stressed but will generally weather the drought out as long as rains come by autumn. There is no point in wasting water on them.
  • Digging an irrigation trench alongside rows in the vegetable garden gets the water closer to the roots that need it, as opposed to sprinkling water on the top. Many vegetables like peas, beans and tomatoes will need water at this time if you want a crop.
  • You can always weed and at least pulling weeds out or push hoeing means that the sun will effect a good kill rate on them by shrivelling them up very fast so you only need to remove those weeds that have set seed. The sun will not kill the seeds.
  • Ignore the brown patches in lawns. Green lawns are a luxury when water is short. Most of the world lives with brown lawns in summer.
  • Unless you have your own water supply, hold off planting even in the vegetable garden until some rain is forecast. You won’t lose anything by waiting another week or two before sowing the winter veg. But if you have water to spare, you can be sowing parsnips, carrots, dwarf beans and brassicas as well as keeping lettuces going.
  • Pinch back cucumbers, melons, courgettes, pumpkins and similar spreaders to keep them under control and to encourage fruit set. Tender pumpkin tips are delicious to eat, as are stuffed courgette flowers, if they are not infested with white fly.

January 25, 2008 Weekly Garden Guide

  • No doubt we are not alone this week in having to deal with the unscheduled arrival of the winter firewood, although with older trees than most people, we may have to deal with more. It is a mystery to us why ours fell on a calm Friday night rather than in Tuesday’s winds but the fires here this year will be fuelled by tawa and pine.
  • Harvest garlic if you have not yet done so. To store it, garlic is best cleaned up and then hung with plenty of air around it in a cool, dark place. The traditional way is to plait the stems but if you can’t be bothered, recycled onion bags can be used (the orange mesh type) as long as the garlic is dry and not packed in tightly. Keep some in reserve for planting in mid winter. Imported Chinese garlic should be shunned in the garden. It is frequently infected by virus which is threatening local garlic producers and it is not worth the risk of trying to grow it. It is also a waste of time and effort because it has crossed hemispheres and its growing season is so disturbed that yields will be poor.
  • Do not be lulled in to a false sense of security by the small amount of rain we had this week. It was not enough to get the moisture content of the soil up and we are highly likely to go back to being very dry. With severe water shortages around much of the province, it is not sensible to indulge in dividing plants and creating gardens which will need watering to keep plants alive. There is not a lot you can do in the ornamental garden in high summer beyond weeding, dead heading, summer pruning roses and general maintenance.
  • As plums are harvested (Sultan plums are worth growing here), prune the trees to keep them open and well shaped. Summer pruning reduces the risk of silver blight getting in on the cut surfaces.
  • It is down to the last week for sowing corn for late harvest in coastal gardens but too late now for inland areas. Planted now, it will hold into the winter and extend your corn eating season into June. Sweetcorn fresh from the garden is much more tender than sweetcorn from the supermarket or fruiterer as much of the sugar content turns to starch very soon after picking. It is also getting late for sowing carrots so do not delay past this weekend on getting carrot seed in for a winter crop.
  • Continue planting lettuces and beans.