About Apios americana (also known as Groundnut or Hopniss)
Apios Americana, Groundnut also known as Hopniss from the Lenape word ‘Hobbenis’ is native to North America where it has long been a staple food for indigenous peoples. It has undergone some domestication and plant breeders have been working to improve it for many years. It has such great potential to become an important high protein food crop and is well worth experimenting with as part of your perennial vegetable garden or forest garden. In the wild, groundnut grows along the banks of rivers and lakes, usually found using trees and shrubs for climbing support. It forms long rhizomes under ground with ‘chains’ of edible tubers resembling a bead necklace. The tubers can be cooked and used just like potatoes but are more nutritious having more protein, calcium and iron. This plant has everything – fantastic tasting tubers, beautiful climbing vines and scented flowers and can fix nitrogen too.
How to care for your tubers
Apios americana tubers need to be kept in slightly damp compost during autumn and winter to stop them drying out until they are ready to sprout in spring. You can keep them in a small bag with some compost in the salad drawer of your fridge, or pot them up and keep them in an unheated greenhouse or polytunnel or cold frame. Check on them regularly to make sure tubers are firm. In spring they are ready to be sprouted and light and warmth will encourage them to sprout and produce their first vines.
How to grow
Apios americana needs moist but well drained soil in sun or very light shade and plants need climbing support. The taller and more vigorous the vines, the better the yield of tubers. Ideally you want to grow it on a 2-3 year cycle. You can grow Apios Americana in a number of ways:
In containers – we use large 40-50L bottomless pots with 8-10ft canes. We mix peat free compost with a bit of potting grit and keep it moist throughout the year. We plant about 4 tubers per pot 4 inches (10cm) deep. The advantage of this method is that your tubers will be easy to harvest and can be tipped out of the container in one go. The plant can still draw nutrients through the bottom of the container.
Direct in the ground – plant 4 inches (10cm) deep 12 inches (30cm) apart. Vines will use surrounding plants or trellis for support. You can experiment using corn, sunflowers, and Jerusalem artichokes as support plants for the vines, or existing trees and shrubs. The advantage of this method is that your plants will fix nitrogen in the soil, the disadvantage is that harvesting is a bit more tricky.
Tubers can be started off in small pots first if you like and then planted out in spring. Tubers are dormant between autumn and spring and will start making shoots when weather begins to warm usually in April. Although the vines die back in autumn, the tubers themselves are very hardy.
How to harvest
Harvest tubers once vines have died back in autumn. If planted in spring wait until autumn of the following year to obtain your first harvest. You could leave some plants to grow on for a further year.
How to propagate more plants
Save some of your best tubers for re-planting. This variety is a triploid, so will not go on to produce pods and seeds but it does produce decent sized tubers with vigorous vines and prolific flowers.
Apios americana shows its first shoots in spring, produces climbing vines over the summer usually about 3m tall followed by dusky pink/maroon flowers in late summer. Vines die back in autumn and tubers remain dormant until the following spring, when the whole process begins again.
How to Eat
Use as a potato either boiled or baked or can be sliced and pan fried in olive oil with sea salt and oregano which is absolutely delicious. As this is essentially a wild edible, we advise that you start with a small portion as some people can have a digestive sensitivity to the tubers.