If there’s a reason why purple is reserved for royalty, it must be because of this bean. Purple Kings are the king of the garden - easy to grow, prolific and terrific in taste.
As I’m writing this, winter is making its last ferocious stand, with torrents of rain and cold. But as soon as the chill fades I’ll be out in the garden to plant a few rows of Purple King beans. Even my fussiest middle child who refuses all green vegetables nods vigorously at the suggestion of a Purple King straight off the vine. I agree with him. Purple Kings just taste better. It’s a ‘wilder’ bean, a flavour that you can’t buy from the shops but can easily grow at home. He’s too busy eating them to notice they’re still green on the inside, with all the natural fibre and vitamins (including folate, essential for brain development) of fresh beans to go with it.
The purple is caused by plant pigments called anthocyanins, which also can be found in red cabbages, purple cauliflower, purple asparagus and hydrangea flowers. It deteriorates in light and heat, so if you cook them, your purple beans will turn back to green. And the purple may vary in intensity depending on the season, the genetics of your seeds, and where you grow them, as the anthocyanins are sensitive to the acidity of the plant sap and soil. The more acidic the soil, the more purple they’ll be.
You can buy seeds for the bush variety, but why limit yourself to a short crop? I’ve always grown vines, which can easily reach 2 or 3 metres in height over a few months. Every 15cm or so will spring a new little bunch of beans to eat, so the bigger vines are better for me! Growing them up a short fence? No problem! Once they reach the top, just train them back down. New growth bends easily and with five minutes of daily attention (while you’re harvesting beans for the day’s lunchboxes) you can train them down or across. What a spectacular living cover for your tired fence!
Leaves can grow to the size of a hand, are dark green, and tend to grow thickly, capable of providing a good summer shade to other vegetables if you train them to grow over a sturdy trellis. They remind me of solar panels, loving the sun. Or you can grow them into a bean tepee, as a summer shade for your kids. Simply attach four or five poles at the top with a rope, and spread the poles at the base. Thread some twine or wire between the poles as support that the beans can grab as they grow. Plant seeds at the base of the poles and encourage them to spread around the tepee, leaving one section as an entrance open for your kids to crawl in and harvest! I’ve also grown them up the poles of my trampoline!
Find a sunny position and prepare the soil with compost, or blood and bone. Soak seeds overnight in water, with a few drops of Seasol or worm wee for invigoration. Plant seeds in damp soil to a depth that’s twice the length of the bean, about 2cm deep. Don’t water for a few days after planting as seeds are prone to rot. They’ll burst through the soil in a week or so. Mulch around them once they’re up. They seem resilient to pests (at least in my garden), and are good companion plants to brassicas, carrots, parsley and lettuce - who value the shade. In about 10 weeks they’ll start to flower, with delicate purple and white flowers erupting in clusters from the vine. From flower to harvest takes about 9 days, and it’s so much fun to watch the daily change.
Baby beans start green. They reach ‘adult’ size at about 15 – 25 cm before they ripen to the purple colour, with some seed development (like little bulging muscles). Pick while they’re still ‘snappable’ and the ‘muscles’ aren’t too big. If you leave them too long they’ll get bigger but tougher, and you’ll have to either cook them or wait until they dry out to harvest the seeds. However be warned: once you let your beans dry on the vine, the vine will start to die (its reproductive mission being over), so harvest frequently for a longer vine life.
You can cook Purple Kings like any other green bean - steamed, baked, or save them in the freezer. We boiled them once, just to see the colour change. Because we can’t resist eating them straight off the vine, or at our most restrained, we run them straight to the lunchbox as a midday treat.