2015 Sweet Potato Catalog

Updated June 21, 2015

Sweet Potatoes



We had exceptionally cold weather with lows in the low 20's late into April. I like to start the sweet potato beds the last week-end in April. It was just way too cold on that week-end (even in the unheated greenhouse). With hesitation we delayed it a week with hopes of a hot, dry May. If sweet potato roots used to make slips (especially the moist orange types) are in cold soil they quickly rot. Our May was not warm and had many cloudy, cool days. Just a handful of the hardiest varieties had slips available by Memorial Day. We continued to have many cloudy days and some of the more temperamental, moist, orange varieties simply rotted in the beds prior to producing slips or produced very few slips. As of this date it is obvious that we will not get to everyone's order much to our disappointment. Some of the varieties are just starting to thrive now that we have had a few days of heat. We are working as fast as we can to get as many orders out as possible. We will start planting our slips on June 28 for the best yields here in Iowa. If you are one of the unfortunate ones who are not going to get anything because we ran out of time, please be patient. We will be sending out the refunds once we get our crop planted. We should have plenty of slips of most varieties for the Season Closeout Specials. If you had a high number or have not gotten your slips yet and could still take them later (June 25 through July 15) please let us know ASAP. Please give us your order number when you let us know you want to carry your order forward to the Season Closeout time.

We are still accepting orders for the Season Closeout Specials (Assortments Only). The cost is half the price listed for the slips (but full price for shipping). You may choose which assortment you would like (but not individual varieties - for new orders). If you are carrying an order over from Regular Season to Season Closeout we will try our best to send what you originally ordered. The new Season Closeout orders must come to us by regular USPS mail with payment enclosed in the form of a check or money order.


You must scroll to the bottom of this page and click on the link that says "Go to catalog of sweet potato varieties". At the top of that page, you will see the link to the Sweet Potato Order Form. Print out this form, fill it out, and send it to us through the USPS along with your payment in the form of a check or money order. We do not accept credit cards, PayPal, internet orders, e-mail orders, or telephone orders. The sweet potato order form has been updated for 2015.

We have the online sweet potato updates for 2015 posted as of December 22, 2014.

Quantity limit on orders:  The maximum number of slips you may order of a variety is only the maximum number of slips listed for each variety. (Example: Korean Purple is sold as 6 slips for $7.50 or 12 slips for $14.00. You may only order either 6 slips of 12 slips. You may NOT order two (2) sets of 12 slips. A total of 12 slips is all that you may order of this variety.) Please respect the limit on each variety as the largest number of that variety we list. This gives more people a chance to try some of the varieties. If we list 3 slips as the highest number, then that means that the most you can order is 3 slips. This may be because the variety is in low supply, sprouts poorly, or is in high demand. This is no reflection on the quality of that variety of sweet potato.


If there is one crop that has more misconceptions that is grown in this country I am sure unaware of it. I can relate to many of these misconceptions as I too had them at one point in time. I can remember being so frustrated with the place that I ordered slips from when I lived in Idaho and the gentleman refused to send them until mid June, eventhough the place where I lived at that time rarely had frost in May. I had read about sweet potatoes since I could read and had read all about how they are a Southern crop and they need such a long season. I never even attempted to grow them when I lived in the high mountain valley of southern Idaho. It just seemed from what I read a waste of time. I waited until I got to the Banana Belt of the Lewis Clark Valley of northern Idaho during my college years before I even tried. The gentleman at the place where I first ordered those plants really knew his stuff and I, now, some thirty years later realize all of the stress he went through trying to get the right information out there about his crop. He kept telling me that you want it hot and stable before you plant them. Eventhough the frost free time was past, I still did not have the heat they need in May where I lived. He was right, of course. They will do so much better if planted in stable, warm soil not just the first day after the last expected frost of the Spring. I do hope those of you first timers and a few who may still be learning do take the time to read the following information. I have faithfully grown sweets ever since I moved to Iowa in 1984 and have taken a great deal of time to try and clear up some of the misinformation out there about this crop. I can thank Lowell Martin for getting me started once I was here in Iowa. Lowell was in his 80's when I first met him in 1985 and he had a piece of "worthless" river bottom sand much like our "worthless" sand hill. Lowell made the desert bloom, so to speak, with his wonderful melons and sweet potatoes. He taught me a lot that first year and one could not argue with his success. The first thing he straightened me out on was, yes, even here in Iowa, you can plant them late. It was after the fourth of July and I was helping him set out his second crop of slips. He told me these will make the best for sprouting and the most uniform. He said they won't get as big as the earlier ones, but they will keep better. And, because they grow so fast, they will have less surface fungii and just all around be healthier. Lowell was right. I have experimented year after year with anything from making monthly plantings from early May to early July. Consistently, the best most uniform roots, will almost always come from the early July plantings. Several years the early May plantings have been a bust with lots of foliage and few roots, while the July plantings have sustained us with the best crop. It really almost always seems to boil down to the heat they receive. The following are some tips that may help you get a crop where your local county extension service thinks you are crazy for trying.

First: Forget what climate zone you are in. That has nothing to do with growing annuals, that is for over wintering plants. Parts of coastal Alaska are in Zone 7B. here in Iowa we are in Zone 4B. If we set out plants in the garden on the same day in both places it is almost certain the folks in Alaska will not have anywhere near the success we will have here.

Second: Do not set the plants out when it is very cool. They hate cold and just sit there shivering waiting for heat. Do whatever you can to make it warm and toasty for them and they will reward you.

Third: Do not think you need lots of roots on the slips when you plant them to be able to insure success. The more roots the more stress when transplanting and the more they will be stunted. The key when setting out the slips is to have very few roots and keep them as wet as possible in the garden for the first seven to ten days. Then back off on the water and they will go crazy. The worst possible thing you can do upon receipt of the slips is to pot them up and wait a few weeks and then transplant to the garden. You will have lost a good two weeks of positive growth and will have given them two chances to slow down. The more you slow them down, the less yield you have. The more times you transplant them, the more nonuniform roots and the less roots you will get.

Fourth: This is the most important thing when it comes to sweet potatoes. It is the heat units that determines success, not the number of days nor plant zone, but heat units. I have been an avid weather observer for almost forty years and have files of weather data to go with files of planting data. This year, thanks to the help of Natalie, I was able to put the two sets of data together and arrive at some conclusions that I had already suspected, but had never had the time to confirm. It takes about 1,200 heat units for our early varieties to reach a decent crop of usable sized roots. I use the term usable sized as I think, for many a sweet potato, the size of a nice fat bratwurst is about the best size for keeping and for baking. Bigger than that is ok, but they do not sprout as well nor keep as well because they suffer from bruising much easier. The question you must then ask yourself is, "How is 1,200 heat units determined?" I offer the following examples. To get heat units you take the day's high temperature (maximum) and the day's low temperature (minimum) and add them together. Then divide by two and subtract 55 from that. That gives you the heat units.

Example 1. Daytime high (maximum) 75 deg. F, nighttime low (minimum) 45 deg. F. Add those together and divide by 2 you get 120/2 or 60. Subtract 55 and you get 5 heat units. If that is your typical Summer, then you will need 240 frost free days to get a crop. It doesn't take a genius to realize that if you have Summertime days like that, you are probably not going to have 240 frost free days because that is 8 months.

Example 2. Daytime high of 90 deg. F, nighttime low of 70 deg. F. That gives you a heat unit for the day of 25 which is just about perfect for maximum growth. Heat units per day greater than 25 seem to have more of a negative impact because of the massive amount of water lost through transpiration. If you can keep 25 heat units a day, then you only need about 48 days to get some usable roots. This is pushing it a bit as there are some limits to daily plant growth. The best growth I have ever seen here is planting around July 18 and having a decent crop by our first frost of October 2, which is about 76 days. By no means do we have temperatures that are perfect for growth each day here in Iowa, but hopefully this shows some data that can help you determine if you can grow a crop.

Fifth: For those who have read the above information and feel that it is now hopeless for them to try to grow sweet potatoes, I offer the following challenge. You can "alter" your heat units in a cold climate. The only way I was able to grow much the three years I spent in the Panhandle of Northern Idaho, where nighttime temperatures got down to the 30's most nights, was to trick or alter the environment. I used Lodge Pole Pine saplings and made an A-frame structure and covered it with plastic. I then enclosed both ends, only opening the ends on the hottest of days and faithfully closing the ends every night. There, the average daytime high was around 80 deg. F in the Summer and around 40 deg. F at night, in other words about 5 heat units a day for most days. by using the A-frame plastic enclosures, I could get it up to 95 deg. F in there in the daytime and keep it around 55 deg. F at night without any supplemental heat source. Therefore, I could get 20 heat units a day instead of 5. I never had the courage to try sweet potatoes there, but by using this method was successful with melons, tomatoes and cucumbers that otherwise were impossible or close to a miracle. You can speed it up even more with planting on black plastic, something I never had access to at that time. Living here in Iowa there are no Lodge Pole Pines so a similar structure could be made out of stiff #9 wire or, if you are talented, plastic PVC pipe.

Once you get a crop, you will then need to preserve it properly. The most common mistake we encounter with folks is storing the sweet potatoes in too cool of a place and not properly curing them prior to storage. The best way to cure them is to dig and do not wash. Then carefully lay them out in a warm area (80 to 90 deg. F) for a week or so to cure. Next, carefully place them in the storage container. Do not just toss them into the container as that will cause bruising and they won't keep as well. We use plastic storage tubs and place the tubs in a location that is above 60 deg. F for storage. If you store them in a place cooler than 55 deg. F, the fungi go wild and thrive on the sugary roots. Also, please remember to not handle the roots a lot as bruising causes the fungi to take over and will ruin your harvest.


Many of you who have ordered sweet potatoes from mainline nursery catalogs in the past cannot understand why, when you have ordered from a company in the northern United States, you are able to get your sweet potato slips more quickly than when you order from us. The reason for this is that with other companies, they are "drop shipped" from growers in the South. This practice is also the reason that some companies are not able to send sweet potato slips to California as we are able to do. Ours is an entirely different operation where the slips are started here on our farm in Iowa from roots that are grown the previous year here on our farm in Iowa. We cannot start the beds any earlier than the first part of May. It is simply too cold.

We start the slips by placing the roots in a slightly dug out area. then cover with peat moss and wet it down. Number nine wire hoops are placed over the area and the whole area is covered in clear plastic (forming a grow tunnel). We lay a soaker hose down the 2-3 foot wide bed and bury the edges of the 50-75 foot long tunnels on both sides with dirt. In the garden it looks like long, clear worms. The beds are not disturbed for the first 2 weeks. Then the plastic is lifted and any weeds removed and a check is made for slip development. Generally 3 weeks after bedding down the first slips are ready to be shipped out. (If we have not had any heat or sunshine during that time, it takes longer for the potatoes to start sprouting.) When those slips are pulled, then more develop and are ready to go out about every 5 days. PLEASE NOTE: The slips for each individual order are all pulled within a few minutes of each other and the order is mailed out that same day. There has been an indication on a gardening forum recently that we pull part of an order on one day and hold those slips over until the remainder of the order is ready to pull a few days later. THIS IS TOTALLY UNTRUE. Technically (and then again it depends upon the variety) every 5 days we have a fresh supply from any given potato. This allows us to make slip pickings about 5-6 times during our normal shipping season of May 25 to June 25.

Please Note: Many people have been asking about what a "slip" is. A slip is a single plant (with small roots) that is sprouted on the sweet potato root and then slipped off so that you may plant it in the garden to grow a sweet potato plant. We ship out only slips (plants), but do not ship out sweet potato roots.

Organic Certification

We have achieved Organic Certification for our sweet potato plants. Our sweet potato plants are started in the field and are grown on soil that receives no chemical treatments. The plants also are not sprayed for insects or disease and are grown organically.


1 through 12 slips = $6.00

13 through 50 slips = $8.00

51 through 100 slips = $10.00

101 through 200 slips = $12.50

(Limit of 200 slips total for each customer this year.)

Please remit separate payments for sweet potatoes and seeds so that if we run out of sweet potato slips we may just return your check to you.

Canadian orders:  We can not ship bulblets, plants or roots to a Canadian address.

International orders:  We can not ship bulblets, plants or roots to addresses outside the United States.

Sweet Potato Shipping To California:  According to the California Department of Agriculture website, we are allowed to ship sweet potato slips from Iowa to California.

Sales Tax

For Iowa residents only:  You must also pay 7% sales tax on sweet potato orders shipped to Iowa addresses. (See order form for where to add this in.)

Go to catalog of sweet potato varieties.

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