Certificated Garden Centres

More than ever before monarchs need our help. In North America deforestation, pesticide use, GM crops and climate change are affecting numbers. Monarch populations are struggling here in NZ too: they are ravaged by social wasps, their major predator.

Commercial growers raise thousands of swanplants (a species of milkweed). Plants need to be in the best condition to be sold. Garden centres cannot sell plants covered with aphids or bereft of leaves, so some growers use pesticides to protect their plants until customers buy them.

Remember a female monarch can lay about 700 eggs (one was recorded as laying 1179!). The caterpillar grows almost 3000 times in size over two weeks. So one day there are lots of leaves but a day later the plant is just a stalk.

The certificated garden centres listed below will not sell plants with pesticide on them and will also be able to advise on nectar sources and host plants for native butterflies and moths. You can be confident that you are buying caterpillar-friendly swanplants here. As well, look below for additional tips on how you can raise more magnificent monarch butterflies.

Tips to raise more magnificent monarchs

  • Grow your own plants from seed – that way you will know for sure whether the leaves are safe for caterpillars. Buy seed anywhere you see Yates products. Yates gives the MBNZT a donation for each packet sold. Plant seed now for next year.

  • Grow plants on from previous years so that they are in their second season and over 1 metre tall. If they are fertilised, watered and mulched the growth in the spring and summer will almost keep up with the caterpillars.

  • When you buy plants, buy twice as many and protect some for next year’s monarchs.

  • Seedlings that pop up in the wrong place can be left until you need food. Cut it off and put it in a bucket of water, splitting the bottom of the stem before you do so it will better absorb water.

  • Caterpillars shed their skin five times. Do not disturb them when they are moulting. Observe the life cycle but minimise handling. Monarchs have been undergoing metamorphosis for hundreds of years without our help.

  • Pesticides such as fly sprays, plug-in insect controls and flea collars on pets will kill caterpillars. Sun-screen and cosmetics on hands can also affect them.

  • If your caterpillars need more food let them move themselves to the new plant. Put the new plant next to the old one or cut the stems with caterpillars and put them on the new plant.

  • Remember, swanplants and monarchs are poisonous so be careful when handling them. Monarchs store toxic steroids (known as cardenolides) from the swanplant and use them as a defence against some predators. The colour orange is a warning to say ‘I taste bad’.
  • There are different types of milkweed, of which swanplant is one. New plant(s) may not immediately appeal to your caterpillars. Water the new plant well to rehydrate it.

  • Buy your plants from a certificated garden centre (listed above) to be confident plants are pesticide-free.