Caring for your swan plants over winter months

Swan plants (Gomphocarpus fruticosus) originate from the Asclepiadiae family, which is a species of Milkweed.  Most Swan plants survive the winter if they have been cared for and nourished with water and re-potted either in a larger pot or into the ground. Sometimes Swan plants struggle to grow back if completely chewed back by the hungry caterpillars. 

This also applies if you have an infestation of Aphids on your plants.  Aphids feed on plant juices, attacking leaves, and the new fresh growth.  You can tell if you have aphids, apart from the obvious and seeing heaps of yellow/orange bugs, (please see inserted photo below). Also by looking at the leaves by noticing honeydew (a sticky substance) which can sometimes develop a fungal growth called sooty mould, causing branches and leaves to appear black.  If your swan plant has been seriously attacked by many aphids it may not survive the winter as it would have become weak. Obviously, you can only spray your plants (if there are no caterpillars feeding the plant) with soapy water which suffocated the aphids as they breathe through their skin. Caterpillars, also breathe through a series of tiny openings along the sides of their bodies, called “spiracles.

Try cutting back the areas where the aphids are in mass. If you just have a few I would recommend squashing them with your fingers and then spraying with a powerful hose with water, your fingers will turn orange but you will get instant satisfaction squashing them all. Be aware Aphids could easily appear the next day if you leave one on the stem/leaf so keep a watchful eye out as they are asexual and left with many the next day.  I plant heaps of nasturtiums as Aphids are especially attracted to these plants. You can plant these near your Swan plants as traps for the aphids. These seeds are really easy to grow – just put them straight into your soil and spread easily. I have heaps of these seeds that I give away to schools for their butterfly & vegetable gardens. I also plant heaps of Marigolds flowers of all different colors around some of my swan plants that are in pots as a barrier, the smell will repel aphids plus add color to your garden.

During peak summer months the aphids will appear in mass numbers, it’s just nature! Remember if your plants are well cared for with great mulch, food, and water. Your plants may not attract the aphids and strong enough to fight them off, ladybugs are also great insects who eat the aphids but ladybugs would have their work cut out if you have many Aphids and may not tackle the problem entirely. Ladybugs also are known to eat the Monarchs eggs.

During the winter months I would recommend gathering up your swan plants in pots and place them in your greenhouse or a friend’s glasshouse if you haven’t got one.  If they are in the soil place a frost cloth around the plant and cover the roots/soil with pea straw to protect the roots from freezing.

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Once the Plants have been striped bare.

Does this look familiar? The photo below was only a few days worth of food for my brood of caterpillars. If you have Swan plants that just stalk make sure you take care of them by frequent watering, plus feeding them with Yates Thrive natural seaweed tonic which reduces transplant shock in new plants, and aids recovery from stress conditions and improves plant resistance, eg: heat, frost, drought, pests, and diseases. I also add in some sheep pellets (which can be purchased from any garden center) into the new pots. Sheep pellets help stimulate green growth and enhance the leaves to grow back quicker. You can also snip back any stems that are not healthy-looking and brown.

These plants will soon be ready for another round of caterpillars for the same summer season. If you have the time, I strongly recommend replanting your plants into bigger pots, with good quality soil. One last thing – CHECK for eggs each day and, if you already have too many caterpillars, then remove or cull them if they are on the stems. Even in late March, Monarchs will still be laying eggs. This is no good as the weather is colder, and you will have a hard job sourcing Swan Plants.  Again trim back brown stems – this aids regrowth. 

Swan Plants, Caterpillar aphids , monarch butterfly.

For more information about caring for your Swan plants and raising monarchs you can purchase my book below.

A Guide On Monarch Butterflies

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16 thoughts on “Caring for your Swan Plants (Milkweed)

    1. I live in Batavia, Illinois. I have two large swan milkweed plants in pots. I am looking for some confirmation as what to do when fall comes for harvesting seeds. I want to make sure I do this correctly as I have never done this before. Exactly when should I pick the balls? October? And when I do, I open the pods and let them dry. Do I plant them in the fall?

      1. Hello lovely to hear from you. I use organiser bags, that go over the pods and when they are ripe to seeds will pop into the bags. Then you can separate the seeds from the silk by quick shake. By covering the pods also protects them from the hungry caterpillars as they will also munch through the pods.

    1. As soon as you see the seed pods dry out and big enough. A good idea is that you can get a organza bag and cover the seed pods so the caterpillars stop eating the pods, and the seeds will explode in their own time in the bag and you have an easier way of collecting the seeds rather them blowing everywhere and wasting.

  1. I have 6 large swan plants.. Some 6 feet high.. Can one prune a swan plant to a reasonable size.? I have a few caterpillars but notice they are actually freezing on the plant..Thanks Bev..

  2. my 8 plants , under a large net ; opened the door and now have plenty of caterpillars.
    My plants are developing an attractive black pattern across teach leaf gradually spreading from each end of the row of plants. Only suggestion i have been given —it is the lack of sun. I am gradually loosing feed leafs.
    Please can you help.

  3. Why do the caterpillars waste so much of the leaves. Parts of leaves are dangling by a thread or loose on the ground. If they started eating at the tip they could eat the whole leaf by walking backwards toward the stem. We have four plants. Two completely stripped, one nearly stripped and a larger plant with 2/3 stripped.. 6 chrysalis, 5 hanging upside down ready to spin, and 17 munching away. It’s started to get cold here but I’m pleased that we have increased the population. It’s Ben more successful than other years. So I’ll keep on next year. We usually have to buy plants every year as our frosts are very hard.

    1. Hello, can you cover your plants with frost clothes and continue watering and feeding through the winter months and the might pull through. Yes caterpillars are so fussy the love fresh tasty leaves. Drives me mad when they waste so much leaves and leaves drop to the ground….yes very messy eaters LOL.

  4. Kia ora,

    What sized pots would you recommend for swan plants (to plant in instead of garden once >10cm tall)?

    1. Hiya,

      10cm pots seem to last for a plants that a healthy 70cm in height, I planted about 100 today into those exact size pots. The bigger the pot the bigger the plant will grow. Maria x

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