Is it a Pea or a Nut?

contributed by Adrian Cram, June 2024

The answer is yes, and no!

The Peanut (Arachis hypogaea) is a legume belonging to the Pea family but it’s seed is technically not a nut. I have been growing Peanuts as an annual crop for about eight years, and they have thrived on the sandy loam soils of the Deua River flats. Although I initially bought the seeds from the Diggers Club in Victoria, I expect this climate may be getting towards its cultural limits as they are typically commercially grown in Northern climates, preferring warmer seasons.

The Peanut is an annual plant growing about 400mm wide by 300mm tall in my patch. It has a leathery, compound leaf made up of twinned leaflets. The small, single yellow flower is about 10mm in diameter. Where it diverges from other peas, is with short stalks connected to the flowers. These are where the magic happens. The plants are insect pollinated above ground, and on pollination, these sharp pointed stalks, (called pegs) will respond to gravity by bending downwards to the soil then burying themselves up to about 100mm deep. The fertilised ovules are carried downwards in the tip of these pegs and will develop further underground to become the netted papery nuts that we are familiar with. This reproductive strategy is called Geocarpy and may be affective against grazers, but I find field mice tend to burrow down for a feed.

My latest crop was harvested mid-May.  I like to harvest just before the frosts as plants start to yellow. If left in the moist soil and with the plant dead from frost, many nuts get left behind as the plant and roots are removed from the soil. These nuts tend to germinate the following November which is a great indicator of when to plant again. I generally plant seedlings from tubes as direct seeded plants mostly have their cotyledons attacked by rats which often ends up with the entire plant being torn from the ground. Being peas, the plants have Nitrogen fixing nodules attached to their roots. I generally apply compost to the beds and liquid feed through growing season. They prefer a sandy soil which also makes harvest easier. Additions of Calcium during bed prep is also beneficial. Plant about 400m apart. One plant will give you about 30 to 40 nuts. I save about 100 seeds/nuts for following years crop which produces about 3-4 kg of nuts. I keep it low as harvesting and removing nuts from roots is very labour intensive. It would require specialised machinery to undertake commercial production. After lifting I rinse plants in water to remove soil, strip the nuts then dry for about 2 months. We either use them shelled and raw with meals or roasted on top of our wood heater in a covered colander.

I suggest you try growing some Peanuts this Summer. The annual life cycle of this plant is fascinating to follow from an educational perspective and like all food production ends with a tasty reward to also be enjoyed.