Yams (oca) are the easiest crop I’ve ever grown. No issues with pest or disease, and once they are planted – you can pretty much forget about them. The only negative is that they are in the ground for a long time, so if you are short on space plant them beneath fruit trees, in flower gardens or perennial edges. Smaller gardens can grow them in containers.
If you live somewhere hot – grow them in the semi shade. A win for cool gardens, they prefer us!
Timing
I start my yams in pots in the greenhouse in October because they need 18° C and my soils generally aren’t warm enough. This gives me a good headstart.
Fill a pot a third with potting mix, pop in the yam, then top up with mix. If soils at your place are warm enough, then you can skip this faffing about and plant them direct into the garden.
Keep them moist and leave them to sprout away until risk of frost has passed and soils hit 18° C.
Soil Prep
A bed of good compost is all you need. Don’t go nuts on foliage producing fertiliser. Free drainage is more important – make a raised row if your soil is heavy clay or poorly drained.
Plant + Grow
Use an organic yam for seed or find seed online. Sethas Seeds sell Henry Harringtons yam – my favs!, especially the yellow ones.
Plant tubers at 5cm deep. If planting your potted yams, just plant to the same depth they were in the pot. A generous 40 cm spacing will bring nice fat yams.
Water during dry spells – they hate to dry out. Mulch is your saving grace, keep it topped up. A living mulch works really well, especially in hot places where tall flowers and crops will shade and cool.
You can leave yams to naturalise and become part of your herbal ley or living mulch. In this case, though you’ll only reap the odd good sized one – most will be small. Tiny even.
Harvest
Yams fatten up from autumn, so don’t rush in to harvest. Wait for the foliage to die off first, or even better leave them until after a frost because they fatten and, like parsnips, become sweeter. Either leave them in the ground and harvest as required or dig up all the tubers and leave them to dry on a wire rack or basket before storing.
Along with all your good sized yams you’ll get plenty small ones. Its just how it is. Pigs love them and great news is, small ones are perfect for next years seed.