Tag Archives: swan plants

Monarch caterpillars and butterflies – a mid-life obsession that is safer than a Harley Davidson

The green swan seed pods and the fat monarch caterpillar in high summer

Mark has always loved butterflies. Alas it was his misfortune to be born in a country with remarkably few butterflies so he has had to focus all his efforts on the only obliging candidate, the monarch. When we travel overseas, he likes to be armed with guides to both local birds and butterflies but at home the yellow admiral and the coppers are largely unknown in our area and the cabbage white does not qualify. The red admiral, which is here, is not as much fun because its main host is stinging nettle. New Zealand has an abundance of different moths, many of which are extremely beautifully marked, but you have to be of a nocturnal disposition for these. This brings us back to the monarch which is large, spectacular and can claim indigenous status because it was self introduced (like the wax-eye), arriving here under its own steam, apparently around 1840.

I admit that I fear his dedication to supporting an exponential increase in numbers of monarch butterflies wintering over may be nearing obsessive levels. Even I was a little surprised at the extent of his swan plant plantations. As magnolia crops have been harvested from our open ground area, he has gone in to the cultivated ground with his little seed sower and trundled up and down the rows dispensing swan plant seed. Strung end to end, we are talking several kilometres of swan plants – probably closer to five kilometres than two. What is more, he is successional sowing in the same way he does with the sweet corn and beans. All this is aimed at ensuring that we have plenty of food to take the monarch caterpillars through to late autumn. That way, they are far more likely to winter over here and there are few close up sights of natural beauty as magical as looking up into a tree on a fine winter’s morning and seeing the monarchs waking and stretching in the sunshine.

The drive to have successional crops may strike a chord with many readers who will be struggling now with a surfeit of caterpillars and a dearth of food. There is something both brave and poignant about watching an exodus of monarch caterpillars heading down from a completely stripped swan plant and wriggling off into the wide unknown in search of another. I suspect Mark suffered some emotional traumas in years past, coping with food shortages. One autumn he raised many caterpillars on slices of pumpkin and he finds it hard to cull babies to preserve dwindling food supplies for the more advanced specimens who are likely to reach maturity and chrysalis in time to metamorphose.

Merely sowing swan plant seed is not enough, however. Definitely not. Crops require management. For starters, you want to try and get at least one plant through to its second season so you can gather your own seed. It germinates readily if sown fresh. We have always known the swan plant as an asclepias, Asclepias fruticosa in fact but it has apparently been renamed Gomphocarpus fruticosus which is altogether too difficult for us to remember even with our experience in horticulture. Sometimes it is referred to as milkweed (it exudes a milky sap) but the term swan plant is commonly understood. The seed pod is like a green bubble swan and when it bursts, the fine seeds come out attached to silky white filaments – maybe they resemble white swan feathers? The filaments help the seed to be dispersed by the wind.

The problem with juvenile swan plants is that the monarchs don’t understand about food conservation so you have to protect your swan plants or they will be stripped long before they become established. If you only have a few plants, you can cover them and restrict access to the egg laying butterflies. These days we have so many plants that the supply finally outstripped demand but in the awkward mid stages, Mark did have to resort to a little infanticide to protect the plants for autumn. And we have to be honest and say that our swan plants are not organic. Without intervention in the form of insecticide, the yellow aphids would have destroyed the entire crop before the monarchs even got going. When he first decided that spraying was necessary a couple of years ago, he went through and carefully picked off all the larger grade caterpillars and relocated them to a clean area. These days we just have too many plants so he tries to get his timing right because insecticide is indiscriminate and will kill eggs and caterpillars as well as the nasty aphids. He tries to do it as early in the season as he can before the explosion of monarch caterpillars.

If you only have a few plants or a single plant under siege from caterpillars, it helps to put in a twiggy branch alongside. Too often the caterpillars will chrysalis on the swan plant where they can be very vulnerable to subsequent generations eating off the stem to which they are attached, so it is better that they be encouraged to neutral territory. Our observations are that cocoons must hang in order to allow the butterfly to emerge undamaged. If you have a stray cocoon, you can try tying a piece of fine cotton to its top so you can suspend it. We have resorted to a bit of sticky tape just across the stem at the top of the cocoon which seems to hold them long enough as long as it doesn’t get too wet.

The final piece of the jigsaw for us is having enough food throughout the year to sustain the butterflies. So it is swan plants as host for the eggs and caterpillars and nectar rich flowers for the butterflies. They will just fly away if you live in a green desert with no food for them. I have written before about butterflies feeding in winter on our Prunus Awanui and Edgeworthia papyrifera. There are many flowers with good nectar but I am slightly amused to see zinnias and marigolds making a reappearance here. We haven’t grown these since back in the competitive school garden days of our children but I notice Mark will row them out in the vegetable garden for the prime purpose of feeding the butterflies. In fact the monarchs have caused him to revisit his approach to the vegetable and kitchen gardens and to give space to many flowering plants in order to feed his butterflies. There is nothing as twee as a potager. We are talking more meadow garden style but it is very pretty. The monarchs are a good argument in support of a gardening style which favours flowers twelve months of the year.

Mark is by no means alone in his monarch butterfly fetish. There is a strong organisation in New Zealand to foster the monarch and readers who wish to know more can visit their website on www.monarch.org.nz . This site will also give further suggestions for nectar rich flowers. One of our friendly neighbours has derived much delight from our monarch butterflies visiting his garden in winter, despite Mark threatening to bar code them and charge accordingly. Send our butterflies home, I heard him say. As far is Mark is concerned, his monarch butterflies give him a great deal more pleasure than a mid-life Harley Davidson and are a lot safer and cheaper.

In the garden, February 12, 2010

  • It is pretty much the last call for heavy pruning on flowering cherries. These need their pruning done in summer to reduce disease. While you are about it, you can prune plums and other deciduous fruit trees straight after harvest. This encourages them to set more fruiting spurs for next year, rather than too much leafy growth.
  • While you are watering container plants (should be done every day), don’t forget to top up the fish pond. Even robust goldfish get stressed if their water heats up too much.
  • While planting in the ornamental garden is largely on hold until temperatures cool or we get some serious rain, mid summer can be a time to give lawns some attention. You can spray for flat weeds now or sprinkle sulphate of ammonia. If you are not keen on spraying, get out with an old carving knife and crawl around the lawn. This last activity is guaranteed to engender a rosy glow of virtue. Never feed a dry lawn – the fertiliser is more likely to burn the surviving grass. If you are planning on sowing new lawns, autumn is the optimum time for this but preparation can start now. The quality of a new lawn can be directly linked to the amount of effort put into preparation. Level the area, cultivate it, remove all green cover and keep hoeing off successive waves of germinating weeds.
  • Vegetable gardens are all about forward planning so while some of us are enjoying full summer (and quite possibly worrying about how to stem the deluge of courgettes), organised home growers are already on the ball for winter. As summer crops are harvested, winter veg are sown and that takes in root crops of the carrots, beetroot, turnips variety and brassicas and leafy greens. Some people start sowing onions this early. You just have time to get a final sowing of green beans but do it asap.
  • Because we maintain active websites (abbiejury.co.nz for published writings and jury.co.nz for garden and plant information), I track google search terms. This week saw somebody looking for advice on how to propagate swan plants (the food for monarch caterpillars) aka asclepias. Seed, preferably fresh seed is the answer. If you sow it at this time of the year and prevent the butterflies from laying eggs on the germinated seedlings and then the baby plants, you will have well established plants next summer which in turn will produce seed. If you have room in your veg garden, it is worth putting a row in. If you are buying swan plants from garden shops at this time of the year, you will end up raising some very expensive monarchs. The idea is to have large, well established plants (bushy and chest or head height) coming ready from now through autumn to enable the monarchs to linger longer into winter.
  • I fear the naïf who googled asking if snails are good for kentia plants (presumably kentia palms) may not have a great future as a gardener. I can not think that snails are good for any plants at all unless squashed and feeding the soil.