Gomphocarpus from seed

One of several plants I started from seed last year was a milkweed nicknamed Hairy Balls or Balloon Plant (Gomphocarpus physocarpus). The nicknames are from the appearance of the large pods that form when the flowers set seed. This plant is native to southeast Africa, but is a good food source for Monarchs here in the United States. I ended up with two very tall and lanky plants. They did not branch and just continued to grow taller throughout the summer. At one point there were a few small flower buds but they aborted before opening. I don't know if this plant wanted more sunshine or something different. It seemed healthy and grew steadily, but I didn't get any flowers. I read that if you are growing these from seed it is best to start them indoors early because the growing season may not be long enough for flowers and new seed pods. Maybe that's what happened in my case.

My tall and lanky Hairy Ball plants (Gomphocarpus physocarpus) in August of last year.

Thankfully, the plant has stayed happy in my greenhouse this winter so maybe next summer I will get some flowers. Ideally those flowers will set seed pods so that I can start new plants from seed and maybe prune my two existing stalks to get a fuller plant.

Open seed pod of Gomphocarpus physocarpus.
Like many other milkweeds, the seed are attached to a fluffy piece of cotton-like material

that helps them disperse in the wind.

Milk Jug Germination

Spring will be here before we know it. Already I am seeing a few blooms on my quince bush, buds on our Daffodils, and leaves from our tulips are breaking through the surface of the soil.

I have seeds of several milkweeds that I would like to grow this year, including three native Asclepias and one Calotropis native to Africa and Asia. The American natives all require cold stratification. I have most of the seeds in the refrigerator, but I am starting a few others using a different method. 

I cut open two milk jugs and added soil to the bottom of the jug. I scattered some of my seeds on the top of the soil, watered them in, and then taped the jugs closed. I’ve sat the milk jugs outside on the ledge of my greenhouse. Hopefully they won’t blow over or become dog chew toys there. With any luck, they will experience the requisite cold period and then will germinate in about a month when the temperature begins to climb and the days get longer and they’ll have a head start in their little biodomes. If it doesn’t work, no big deal. I only used part of my seed stash on this experiment.

I did a little more reading on this technique and apparently it's important for the top cap to be removed. I was assuming more of a close greenhouse/terrarium setup was desired, but I will stick to the recommended method and remove my top caps.