Potatoes are a nutritious and delicious staple food and, says Zambian farmer, Chanda Chibesa, they are easy to grow in bags on small pockets of land. Good news for small-scale commercial farmers and for householders looking for ways to put food on the table and diversify the menu.
Potatoes, tomatoes, chilli peppers, tobacco and brinjal (eggplant) are members of the Solanaceae family – also called the Nightshades. How relevant is this information to you, the small-scale commercial farmer, you may ask.
Those of you who farm tomatoes know that diseases can wipe your crop out. And it’s the same with all the solanaceous plants; so be aware of diseases and scout your food gardens and farms diligently.
South African based ZZ2, possibly the biggest grower of field tomatoes in the world, uses Brinjals as pest indicators and plants buffer rows on the boundaries of tomato fields.
The solanaceous plants must be rotated if they are field planted and should not return to the same field for four seasons. One of the benefits of growing potatoes in bags is that you won’t have this problem.
Potatoes are grown from seed, rather than ‘seeds’ as we understand them. Seed potatoes are potatoes that have been grown under specific conditions and are certified disease-free. They are roughly the size of a chicken egg but may be larger. Commercial growers plant seed potatoes, they do not toss last year’s potatoes into the ground and hope for the best; the disease risk is just too high. And neither should the small-scale farmer who may want to expand his bagged potato operation in the future to a field operation.
The seed potato is pocked with ‘eyes’ from which buds develop and start sprouting. Every housewife has seen this in potatoes that have spent too long in the vegetable rack.
Put the potato seed into egg boxes (or a storage container of your choice) in a warm location about a week before planting. To make your seed go further, once it has started sprouting you may cut it (in half, quarters or smaller) as long as there are two sprouts on each cut piece of seed. Use a sterilised blade to cut your seed and then hold the cut seed in a well-aired warm store for three or four days.
Several types of bag are suitable for growing potatoes – hessian, feed bags and plastic rubbish bags (must be the durable type). Permeable bag material has ‘built-in’ drainage but if you are using heavy duty plastic bags, pierce drainage holes in the bottom of the bag. If you plan to use a small (8 litre) bag, plant one seed potato. Bigger bags can take three or four seed potatoes evenly spaced.
Roll the bag down and fill the bottom with about 10cm of compost mix. Then place the seed into the bag with shoots pointing upwards and cover the tubers with compost. Once the plants have grown to between 10cm to 12cm start earthing up (covering) around the stems. Keep adding compost and unrolling the bag as necessary. Covering the potatoes like this encourages rooting and a bigger tuber population.
FLOWER AND HARVEST
About 10 weeks after planting, flowering will start. At this stage the bag should be just about full of soil and compost. Now is the time to harvest the early potatoes. There is nothing more delicious than a home-grown baby potato, boiled or steamed, with butter. If you prefer to wait for the main crop, let the flowering stems and leaves die right back and harvest two weeks later.
Potatoes like full sun but potato tubers don’t so keep them covered. They need a moist soil but don’t drown them with over-watering.
They also need a scout with good eyes to pick up diseases in time to take preventive action.
If you farm in the neighbourhood of a big seed potato or commercial potato operation, go to the farmer/s before you start growing potatoes. Ask for their advice about disease control. They may prefer to supply you with potatoes rather than risk the disease to their fields.
On a large-scale, crops like potatoes and tobacco can be very tricky and the inputs for seed potato especially are jaw-droppingly high. Remember they grow to make sure you get disease-free seed and one disease outbreak is enough to condemn their crop and downgrade it from seed to commercial.