Sweet Potato Care
Now that your sweet potatoes are growing, here's how to care for them to get the best crop.
It's important to take care of any weeds that pop up soon after planting, because they'll steal water, nutrients and sunlight that your sweet potatoes need. If you delay cultivating, the quick-growing potato vines could sprawl and make it difficult to walk between the rows to get to the weeds. Before the plants have begun to produce runners, gently stir up the soil around the plants and in the rows to get rid of weeds. This also aerates the soil, letting the roots breathe easily.
After a while the many large sweet potato leaves tend to block out new weed growth. After the vines spill out into the walkways, your weeding is all but finished.
Watering is very important in the few days following planting. Be sure to keep the soil around the slips wet, so the roots can start to expand quickly.
Once the roots have anchored the plant well, sweet potatoes can be considered moderately drought-hardy; they'll take some dry weather and still yield fairly well. If you can steer around any dry spells with proper watering, great! The plants need about 3/4 inch of water weekly at the beginning of the season and up to 2 inches weekly in the heat of midsummer.
As with white potatoes, the plants will develop growth cracks after enduring a severely fluctuating moisture supply. These will heal in time and won't damage the cooking quality, but the appearance of the sweet potatoes will definitely suffer.
Mulch can be important for retaining the moisture necessary for good growth. One technique is to lay black plastic over the soil ridges before planting. Do this after a rain, when the soil is moist, then plant your slips soon after. The plastic holds in moisture and traps heat, helping to give the plants the "tropical" atmosphere they love.
Other mulch options include layers of newspaper, leaves, grass clippings, compost or any other organic material that will conserve soil moisture and choke out weeds.
After the plants take hold but before their vines really start to run along the ground, give them more fertilizer as a side-dressing. Try one cup of 5-10-10 per 10 to 12 feet of row, applying it thinly on both sides of the ridge. Bonemeal, high in phosphorus, is also a good side-dressing fertilizer. Apply one cup for each 20-feet-of-row.
Extra side-dressings every four or five weeks are important, too, especially if it rains often, because rain washes nutrients down through the soil.