Sweet Potatoes

Selection and Planting

Sweet Potato Varieties

Seed suppliers usually carry a handful of different varieties of sweet potatoes.  Local stores, however, will often only have one.  Beauregard is one of the most common varieties and grows well at Rose Tree Garden.  Another common variety that grows well is Covington.  As you become more experienced, you may want to try some others that may provide you with different tastes.  No matter the type of sweet potato you choose, they all grow in a similar fashion and take around the same amount of time to grow full-sized tubers.

Sweet potatoes are vining plants and require a lot of area to grow.  This, along with their relatively low cost in stores, makes them not as common in Rose Tree Garden as other plants such as tomatoes.  However, with proper planning, they can be a rewarding plant to grow.

Planting

Sweet potato plants are grown from slips which are vines that sprout out of a sweet potato.  When they get to an appropriate size, the slips are broken off the sweet potato and either planted directly into the ground or placed in potting soil to be transplanted a couple of weeks later.

In order to grow your own slips, obtain a sweet potato from a garden center around mid to late March or order one from a seed supplier.  Place three to four toothpicks around the middle of the sweet potato and place it on the brim of a mason jar.  Fill the jar with fresh water until the bottom 1/3 of the potato is submerged.  Place and a sunny spot and wait.  Replace the water in the jar twice a week to ensure the water stays clean.  After a few weeks you should begin to see sprouts coming out of the top or sides of the sweet potato.   These are your slips beginning to form.

If you would rather not go through the trouble, slips can be purchased from most reputable seed suppliers including Johnny’s Seed and Park Seed.  They tend to sell out closer to planting season, so be sure to order them ahead of time.

As planting time approaches (early to mid May), begin checking the 10-day weather forecast.  If the nighttime temperatures are predicted to be under 50°F for any of those 10 days, wait to plant.  Sweet potatoes are a warm weather crop and do not tolerate cold temperatures.  It is always better to wait than stunt the growth of or kill your sweet potato slips.

Because sweet potatoes grow best in loosened soil, we recommend forking the area or breaking up the surface with a hoe.  We advise against using a rototiller in order to maintain the soil structure around the plants.  Place the root end of your sweet potato slips 2-3″ below ground spaced 1 – 2 feet apart.  Mound up soil around each slip so that the stem up to the bottom leaves is covered.  As the plant grows, increase the size of the mounds to encourage the roots to grow inside of the mound of loose soil instead of trying to push into the hard soil underneath.  Unlike with regular potatoes, exposed sweet potatoes are not negatively affected by sunlight, but they do make them easier for small animals to get, so make sure your fence is able to keep them out.

Growing Sweet Potatoes

Pests

Sweet potatoes at the Rose Tree Gardens are susceptible to few insect pests.  The majority of the issues people have growing sweet potatoes comes from rabbits, groundhogs, and deer which all love to eat sweet potato leaves and roots.

Caterpillar Damage

Caterpillars consume the leaves of plants, especially younger leaves.  Numerous holes or large portions of the leaves missing indicate caterpillar damage.

Diseases

Sweet potatoes are susceptible to various diseases, but at Rose Tree Garden, these diseases have not been spotted.  However, even though sweet potato diseases have not been seen, crop rotation is encouraged.

Watering

An establisehd sweet potato plant has a very large root system that is capable of finding water far below the soil line.  Because of this, they don’t require regular watering.  If they experience extended periods without rainfall (see the Rose Tree Garden Weather Data), supplemental watering may be necessary.

If you do decide to water, be sure to water slowly at the base of the plant over a period of an hour to encourage deep root growth.  Long and infrequent watering encourages the plant to focus on root development which will enable it to survive through periods of drought. 

Weed Control

Keep area under sweet potato plants clear of weeds to prevent competition.  Because of the mounds of tubers, only hand weeding is encouraged.  Reduce the weed pressure by following our Weed Prevention suggestions.

Harvesting

At Rose Tree Garden, sweet potatoes are ready for harvest around early October as cooler weather becomes more common.  Because they a warm season crop, you shouldn’t wait too long to harvest as long frosts can ruin the crop.

In order to harvest, begin by trimming all the vines off the plant so you’re able to clearly see the mound.  Starting about 1.5′ away from the plant, sink a shovel into the soil and gently pry up in order to loosen the soil around the sweet potatoes.  Do this in a ring around the mound.  You want to stay far away from the mount to keep from damaging any of the tubers.

After the soil has been loosened, remove the soil around the tubers by hand.  If needed, loosen the soil again until you’re able to easily free all of the sweet potatoes.  If done correctly, all the tubers will be concentrated in a small group.

After harvesting, let the tubers sit on the ground in the sun for 2-3 hours so they have time to dry before moving onto curing.

Storage

Sweet potatoes are able to be stored for up to a year through a process called curing.  This is when the tubers are exposed to a warm (80-90°F) and humid (~90%) environment for about a 10 days.  After curing, store them in a cool (55°F), dark, dry place.

There are two simple ways to cure your sweet potatoes.  These are described below:

  1. Oven Method: Place your sweet potatoes on the top rack in your oven.  On the bottom rack place a pan filled with water.  Turn on the oven light (do not turn on the oven itself), and close the door.  The oven light is capable of keeping the oven at around 90°F.  Monitor the temperature and humidity to make sure they stay at the desired levels.  After 10 days, remove the sweet potatoes for final storage.  Allow your oven to completely dry out before using it for anything else.
  2. Plastic Bag Method: Place your sweet potatoes in a single layer on top of some crumpled newspaper inside of a plastic bag.  Loosely tie the top of the bag and place it in a warm room for 10 days.  After the time has elapsed, remove the tubers from the bags and store them in a cool, dark place.  Periodically check the temperature and humidity inside of the plastic bag to ensure proper curing.