Around September I start getting really nervous about having enough space for the Winter garden. There’s always this back and forth in my mind about what plants need to be pulled, which plants I can’t bear to let go, and how is the weather going to cooperate. This year I grew a patch of sweet potatoes in my garden for the first time, and around the end of September I started to wonder if it was time to harvest? If you are curious about growing and curing sweet potatoes in Southern California,  I’m sharing the journey below—- from slip, to harvest, to table.

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Before my Growing & Curing Journey

Have you heard that sweet potatoes are easy to grow? I did. So, in a dedicated bed for the last 4 months, I had sprawling sweet potato vines growing in my garden.  Surprisingly, they were easy to care for, loved full sun, and needed no attention at all.

If you are just beginning to grow sweet potatoes, you should know that they are best grown from “slips” rather than planting a whole sweet potato in the ground. Sweet potatoes aren’t grown from seed either.

Rewind to early May 2020. I had ordered sweet potato slips online because every attempt to root my own slips from a sweet potato failed. Yes, I tried sticking the end in water. Yes, I tried burying half the potato in soil. All those Pinterest tutorials and Youtube videos touting how easy it was just did not work out for me. In frustration, I decided to just order my slips online and I purchased a collection of 75 slips for about $35. UPDATE: once I had grown my own sweet potatoes, starting slips from my own supply was super simple! Read all about it: How to Start Your Own Sweet Potato Slips

Just so you know, 75 slips is far too many for a small backyard gardener. I used maybe 10 for my small 5′ X 3′ plot? and had to give the rest away.  Lesson learned.

Planting Sweet Potatoes

In early May I received my slips and started to prep my plot for planting the sweet potatoes. You can read How I Amend My Garden Beds Organically if you are curious how I prepped the soil for my slips.  I had read that sweet potatoes should only be planted outside when it is warm and the temperature is consistently around 70 degrees F, so I waited until mid-May before planting my slips into the ground.

My biggest surprise was how hardy these sweet potato plants were! After arrival, my slips were left sitting on the porch for a few days. I had put them in water, but noticed that all the foliage was looking really tattered. Surprisingly, once I planted my pathetic sweet potato slips in the garden, they took off! What started off as stringy, tiny rooted sprouts became full vines with glossy green leaves and the ability to send out shoots all over! Apparently, sweet potato plants are super hardy and vigorous.

I planted my slips sporadically around the garden bed. Most sources gave spacing recommendations for sweet potatoes based on rows but, since my bed was a peanut shape I left approximately 12-24″ in between each sweet potato slip. Remember, you want to grow sweet potatoes in full sun. 

Sweet Potato Growing Season

Overall, the sweet potatoes continued to grow from mid-May to the end of September unattended. For the entire growing season, I simply kept my sweet potatoes watered. To this day I don’t know if I was suppposed to prune the vines or lift them off the soil to prevent rooting as the season progressed. See, when a sweet potato vine rests or touches the soil, that part of the vine will send out roots—-almost like a strawberry runner will root. Eventually, my vines cascaded beautifully over the edges of my garden beds, into the pathways, and I didn’t have to worry about extra rooting anymore. I just let them be. Now that I had sweet potatoes growing, I started to worry about curing them!

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When should I harvest sweet potatoes?

This year I harvested my sweet potatoes at the end of September. In restropect, I think I harvested just a couple weeks too early. This was not because of the size of my sweet potatoes, but more because of our weather patterns. It was too warm for too long here after harvesting that some of my sweet potatoes started to sprout (this is also because we do not have a special storage area or root cellar that stays cool enough for the potatoes during warm weather). Next year I’ll aim to harvest about 2 weeks before our cold weather truly sets in. 

The majority of information I came across online said to harvest sweet potatoes when the vines had started to yellow and die back. As with most things growing here in Southern California, the vines don’t necessarily die back. Thanks to a really REALLY long growing season and mild weather, many plants that are supposed to “die back” can hang around for what seems like forever. It’s usually up to the gardener to decide when to cut a plant back or pull it from the garden.

One thing I decided to do was to take a peek at my sweet potatoes to see if they were at a harvest size. Most of them were larger than the grocery store, so I figured it was probably time to harvest.

During the time I harvested, the daytime temperatures were between 80-95 degrees F and the nights were still very warm (like 60-70). In my opinion, it is best to wait to harvest until the daytime temperatures are between 80-95 and the upcoming forecast has nights dipping into the 40-50s within 2 weeks. This is all because of the curing process and because I don’t have any basement, root cellar, fancy equipment, or traditional vegetable storage areas. More on how to cure your sweet potatoes below….

Tips for Harvesting Sweet Potatoes

To harvest our sweet potatoes, we gently dug around the base of the vines with our hands to reveal the tubers. They are very fragile at this stage and can easily break—which could harm their ability to store. Excavate that tuber like an archaeologist digging up dinosaur bones!  Later, I found that the sweet potatoes that broke did cure alright, but I put them in a pile to eat first because they don’t look like they would store as well.

The Sweet Potato Curing Process

See that sprouted sweet potato above? That’s what we don’t want. That sprouted potato will not store very long and will not have had the time to concentrate all its sugars into that deliciously sweet flavor we expect from our sweet potatoes. That sweet potato pictured above will probably be my project for keeping alive over winter to create slips for next year (woohoo my first success at growing slips!) haha.

So what was my sweet potato curing process and what went right or wrong? After doing a little research, I decided I was going to utilize an insulated cooler bag (pictured below) to start curing my potatoes. I already had the bag, and you know how much I love using what we already have around the house.

The first step of curing is a 8-10 day (slightly negotiable) period of sitting in a humid environment with the temperatures between 80-95 degrees F. After harvesting I did not wash my sweet potatoes. Although I wiped off any major chunks of dirt, I found that the moisture from the soil coating helped to create the necessary humidity in my insulated cooler bag. To start the curing process, I simply put my potatoes into a plastic bag and zipped them into the insulated cooler bag. The plastic bag was there because I wanted to keep my insulated bag clean!  I placed the insulated bag in my warm garage and left it for 8 days.

Taste Test after 8 days

After spending 8 days in an insulated cooler bag in our garage (which was between 80-90 degrees), I decided it was time to try a small sweet potato piece. The information out on the internet regarding curing was so overwhelming.  Some sources said you only needed 4 days, some said 10, and some said 2 weeks. I’m going to be really honest and say that I randomly decided I was going to try them at 8 days.

I picked a really small piece, washed it, peeled it (because I couldn’t get some of the dirt off), and then pierced it with a fork. I then microwaved the sweet potato in small increments until it was cooked thoroughly for tasting. In retrospect, the piece was a little too dry because I had peeled it, but my goal was to see if it was sweet so I wasn’t too picky.

After 8 days the sweet potato was slightly sweet but not at all as sweet as grocery store sweet potatoes. I can say it wasn’t even as sweet as a carrot or roasted butternut. The result was really disappointing, and had me doubting if I’d ever bother to grow sweet potatoes again. Being a small space gardener, I really focus on choosing vegetables that I enjoy eating and that grow well in my climate.  If I was going to give any room to sweet potatoes in my garden again, they were going to have to be sweeter than that…..or else I’d leave the sweet potato growing to professionals.

Related Article: Top 10 Flowers for a Potager Garden~ Calendula made my list!

Two weeks in the humid and hot curing bag…

After the disappointing taste test, I accidentally left my sweet potatoes in the cooler bag for another 6 days! As I went to transfer my sweet potatoes from the humid curing bag into a more permement, cool and dry storage area I noticed that some started sprouting! I panicked. What?!!! I knew that sprouting was not good for longevity, so why did my sweet potatoes start to sprout?

My reading led me to conclude that because the temperatures were so warm consistently, the tubers we fooled into thinking that it was “summer” and that it was growing time. So now you can see why I said the 2-week forecast should display lower night temperatures into the 40-50s. After humid curing, sweet potatoes need to be stored in a cool environment to avoid sprouting.

My first mistake was to harvest my sweet potatoes before we started getting cooler evenings AND I left them in the humid bag too long. Next time, I’ll leave them in the humid bag for 8 days.

Did I taste them again after two weeks? You bet I did! I chose another small piece and went through the microwave process again. Lo and behold, it was sweeter! Hooray! Still, my sweet potatoes still were not as good as the ones you buy at the grocery store and, for gardeners who have small spaces, we have to be very choosy about what we grow and what plants get space! The verdict was still out for me…..

Transferring the sweet potatoes to cool storage

At this point I had resigned to use up the sprouted sweet potatoes first and also save one for creating more slips for next year. These are the times that truly show me how growing in Southern California can be so different.

I still hadn’t washed my sweet potatoes. After removing them from the insulated cooler bag, I simply brushed off as much dirt as I could, wrapped them in newspaper, and placed them in a storage crate (on the left in the photo below). By now, the nighttime temperatures were dipping down into the 40s and 50s, so my garage stayed cool enough to store them and hopefully not encourage any more sprouting. Ideally sweet potatoes should be stored at about 50-65 degrees to avoid sprouting. Truth be told, our homes don’t stay cold enough for proper storage, outdoors is too hot now (still between 70-90 during the day), and many of us don’t have basements or root cellars. The garage is my best option, and it works when our nights have finally surrendered to the colder temperatures of Fall. I have this issue when choosing how to store my garlic as well.

The final taste test!

Are you still with me? We are currently in November, have cured our sweet potatoes for 2 weeks in a humid environment (I’d go with 1 week), and have transferred them to a cooler storage area for another 3 weeks. At this time, I wanted to taste test again!

This time, I decided to go big. I chose a larger sweet potato than the tiny piece I chose last time, and actually baked it in the oven until it was cooked through and fluffy.

Does victory taste sweet? Yes, yes it does. It tastes like a deliciously SWEET sweet potato.

Lessons learned growing & curing sweet potatoes

Growing and curing sweet potatoes in Southern California is possible (yet different) and worth it.

You don’t need that many sweet potato slips. Definitely don’t buy 75 for a small 3′ x 5′ patch, okay? From my 10 sweet potato slips, I grew about 18 pounds of sweet potatoes—-which I don’t think will break any records, but now I know so much more!

Definitely wait until the weather has warmed before planting your slips (this year that meant mid May-early June). Sweet potatoes love the heat and like full sun!

In a mild climate (I’m zone 10b) your plants will not die back in a Fall frost, so time your harvest based on when you planted, the weather, and after sneaking a peek at the size of the sweet potatoes!

I don’t think I’ll have to buy slips again. Aside from some of the potatoes that are sprouting already, I also left some small ones in the ground and they are rooting too. I think I’ll be able to create my own slips for 2021!

Last but not least, this was fun.