UC Master Gardeners, Santa Clara County, CA
University of California
UC Master Gardeners, Santa Clara County, CA

Sweet Potatoes

Garden Help > Vegetables

The Basics

Sweet potatoes on raised bed MG Cindy Day
When to plant

  • Start slip production in February–March
  • Transplant to garden May–June

How to grow

  • Sweet potatoes are grown from 'slips' (sprouts from a sweet potato). Due to pest quarantines, most nursery companies cannot ship slips to California
    Sweet potatoes covered in plastic Karen Schaffer
  • To grow your own slips:
    • Start in February or March
    • Fill a shallow container that has drainage holes with moist potting soil.
    • Nestle in the sweet potato so it is half covered in the soil. Place in a waterproof tray.
    • Cover to retain humidity and keep it warm.
    • Remove covering when sprouts appear in 2–4 weeks
    • When sprouts are 6" long, clip off 1" from potato (to prevent possible disease propagation from the mother potato) and plant directly in pots (or root in water then transplant into pots)

Care overview

Sweet potato rooting the slips Karen Schaffer

  • Sweet potatoes grow best in light, loosened soils
  • Do not over fertilize with nitrogen which encourages leafy growth at the expense of roots
  • Wait to transplant until soil temperature reaches at least 70°F and night temperatures rarely dip below 50°F, typically May or June
  • Plant rooted slips 12 to 18 inches apart. Do not crowd -- plants need lots of room to develops large roots.
  • Once the vines spread to cover the ground, little weeding is required
  • For best harvests, prevent vines from rooting along the stems by mulching the soil, lifting the vines off the soil periodically, or trellising the vines.
  • Leaves and young shoots are edible and make a fine spinach substitute in the summer

Pest management

Harvest window

Sweet potatoes in barrel MG Cindy Day

  • Sweet potatoes take 3–5 months to mature, so harvest in October–November. Leave in the ground until the roots are full grown and the vines begin to turn yellow
  • Stop watering 2 weeks before harvesting
  • Dig carefully to prevent skinning and bruising. Do not wash immediately because the skins are very tender
  • Allow newly harvested sweet potatoes to dry in the garden for a few hours


  • Curing improves flavor by converting starches to sugars, helps minor scrapes heal over, and increases storage time
  • To cure sweet potatoes, store them in a warm, humid place (80 – 90°F, 85% relative humidity) for at least 10 – 14 days
  • Placing a damp paper towel in paper bags of sweet potatoes is one way to create a humid environment


More links

Recommended Varieties for Santa Clara County

There are no specific variety recommendations for Santa Clara County yet. The UC Davis Vegetable Research and Information Center's sweet potato overview lists some recommended varieties for California.

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