How to Grow Sweet Potatoes

I am a professional sweet potato grower. The following is my current understanding of growing sweet potatoes on a small scale, organically, and respecting regenerative agriculture ideals. These instructions will give you yields that can be higher than conventional methods if followed. The simple summary is for the backyard gardener. The more detailed explanation explains how to increase results by understanding the soil-food web. I also have a Sweet potato comic at the end.

“Sweet Potatoes are easy to grow”

Said to me by an old Florida sweet potato farmer.

Once upon a time, I dropped a sweet potato at the edge of the woods on the way to feed my chickens, and the next season it was vining out and taking over along the fence line. You can not stop these plants. Scoring heat, apocalyptic rain, and drought, even insects are a joke to these highly developed plants. Novice gardeners fear not and grow sweet potatoes.

Why grow your own Sweet Potatoes?

• Taste – They taste out of this world (my life revolved around lunch and dinner)
• Survive -They are a survival crop (food inflation and all). I am not a Malthusian, more of a romantic. I think everyone can homestead a little. Think ‘Little House on the Prairie’ or the Amish.
• Healthy – They are good for you (high in antioxidants like quercetin, carotenoids, and anthocyanidin and low on the glycemic index, which is good for your waistline)
• Pets -Dogs and pets love them (dogs know what is good and not good)
• Greens – The leaves are edible and good for stirfry and wraps, as a substitute spinach
• Store – They store well (cure sweet potatoes and you can have a year’s supply)
• Can grow anywhere -In warm climates, they permaculture or you can have two crops and Northern growers can mitigate the winter if you know how to ‘push the zone’.
• Therapeutic – Get out into the garden and work your worries out. Monks have a philosophy of ora et labora. That is, ‘pray and work’, but really labor. Do something physical in your work as it transforms your world and your inner self so you can, forgive, and be a light to others.
• Easy -Easy to grow, for the novice gardener and lots of fun

A note on store-bought sweet potatoes – even locally grown, are sprayed with loads of chlorpropham, a sprout inhibitor that can not be removed (I have tried), as well as insecticides and other nasty chemicals. They do not even taste like the ones I grow. I personally can not eat them, and would not feed them to my family.

Better is to learn to grow your own sweet potatoes, It is so much fun and easy, you will see.

• Alternative Growing Quick Tip: Some of the best results can be obtained from growing in cardboard boxes. I know you would think grow bags and pots and garden boxes, but simple cardboard boxes seem to do well. They are free from any store. Just have a depth of at least 6″ and, better, 12″ or more. Try cardboard; it suppresses weeds; it decomposes nicely and without additional plastic or other forever resources.

A simple summary of how to grow sweet potatoes :

1. Well-draining soil, elevated is optimal.
2. Warm soil, 60 F or 15 C degrees and up, full-sun.
3. Spacing, 8″ or 20 cm, more if you have the space.
4. Watering, 2 to 3 times a week.Fertilize/mulch with homemade compost or manure (discussed below why).

Explanation of how sweet potatoes thrive for high yields

Understanding the genesis of sweet potatoes is relevant for growing sweet potatoes in your garden or field. Sweet Potatoes came initially from Central and South America. They are flowering dicotyledonous plants from the morning glory family. Further, contrary to popular belief, they are related to potatoes. They are cousins from the Solanales family of plants. Although not in the same branch, they share similar growth characteristics as both Sweet potatoes and Potatoes are tubers or root vegetables.

Before planting, think about the Yucatán Peninsula, the Andes, and even the Caribbean. These are the origins. 

Meditate on the Polynesian islands and the Pacific. These parts of the planet are where the Spanish transported them to. The climate and geographical characteristics in these regions are where they thrive with little effort. The Yucatán Peninsula has a peak in the center, as does the Andres; this means elevation.

Sweet potatoes thrive in warm, well-draining soil and elevation. As subtropical plants, they like to run on the ground and act as ground cover but will climb if they have to. 

Create a Micro Climate

Another characteristic of these areas is that they tend not to be deciduous; the leaves do not fall seasonally and replenish the soil. They are semi-tropical or tropical jungles where the soil’s nitrogen content is not high, but the earth is often rich in minerals but not nitrogen.

In warm regions, you are all set unless you want to permaculture it over to the next year as I do. In Northern regions, you can grow sweet potatoes up to zone 3 if you grow them on your porch or the south side of your house, or under a sun tent greenhouse. Do not let the USDA growing zone 7 to 11 intimidate you. I know someone in Poland who only grows tropicals outside.

Use your imagination and grow by creating a climate, is that not what “Martian Potatoes’ are all about? Make a geodome if you want to get fancy or used recycled glass you collect and piece it together, but have fun with your structures.

Often they are in areas where there was a previous volcanic activity – coupled with the proximity to the ocean.

Raised soil

The main point for the home gardener is to plant them on a mound, ridge, or in a grow bag or container with elevated, well-drained soil. If you plant them in a flat field, make sure the water does not accumulate after heavy precipitation. I have a flat field, but the soil is sandy in my area, and through years of soil augmentation, the field is higher than the rest of my landscape, so it drains well.

Place compost over existing growth – In the far garden box, I will just dump compost on top of the green growth, so it looks like the front box.

Raised bed boxes are my favorite way to grow because they look nice. I want beauty in my garden.

• Elevate – easiest more economic way is Hügelkultur culture (kurgan culture). Take debris like leaves and logs, and sticks and cover them with soil. I use this method in garden boxes and bags.

I do not use galvanized steel garden boxes. This is popular on the web, but the ones I test contain lead, Pb, the metal. These are Youtubers, not PhDs recommending this. Do your own tests on galvanized steel garden boxes and lead.

Better is, if you are low in resources, you can get logs from the woods or scrap wood at a discount at the home improvement stores. I use cedar or cheap untreated wood and coat it with oil. I think treated wood is safe these days, but I still prefer cedar or free or cheap alternatives. Some people use air crete and alternative materials. If you want an out-of-the-box solution, maybe polycarb corrugated panels, but I still prefer natural like wood and stone. It does not have to be picture-perfect. Good enough is good enough. Use the local resources at hand. I know a person who made a greenhouse from collected free glass.

I pile organic matter on top of the existing garden box. I might grow a cover crop and then not even cut it, just place compost on top. The cover will decompose under it by the time the roots reach the green matter. The idea is not to till the soil and disturb the soil as little as possible. The good news is less work is more.

Note above, I use contractor-grade tarps as anything else in Florida degrades. I live in a jungle and if I do not tarp there are a lot of creeping weeds. Up North, I might use cardboard or mulch. In my field, I tarp and remove.

How to fertilize sweet potatoes

• Fertilize with P and K rather than N. N will produce green leaves. P and K larger potatoes.

Here is an example of a reference regarding yield (I use organic): Sweet Potato fertilization

One of the reasons I choose to specialize in Sweet Potatoes is they are one of the most sustainable crops on the planet. They have low nitrogen requirements and can grow in most of the world’s growing zones with fewer resources. They could, in theory, make a significant dent in the issue of world hunger.

Organic fertilization is about feeding the soil. I am not detailing inorganic fertilizers as sustainable organic fertilizers have greater long-term effectiveness and cost-effectiveness. To analyze this claim, use a bag of 10-10-10 in a separate area and compare the results against an organic area over several years. I think the results will surprise you. However, you have to compare the taste and nutritional value of the sweet potatoes over the long run.

Soil Amendments for Sweet potatoes ranked by cost/effectiveness.

Manure

1. Green Manure (feed store alfalfa pellets 40lbs bulk)
2. Steer (helps with good soil bacteria).
3. Chicken (I use a chicken tractor).
4. Rabbit.
5. Horse manure (not recommend unless you are positive, it is not contaminated by aminopyralid).

Compost composed of:

1. Forest compost.
2. Alfalfa pellets (these are magic as they contain triacontanol, a root stimulate as well as trace minerals).
3. Seaweed.
4. Food compost, organic I put everything in here, no rules.
5. Leaf mulch (your neighbors will even bag it and leave it in front for pick up).

Try buying alfalfa pellets from a feed store for less than 20 dollars for 50lbs. use your imagination on how to break it down; I use composting worms collected locally from the forest. Others mix organic matter in, such as fish or urine, to speed decomposition.

Innoculate with IMOs

Indigenous Microorganisms create the soil food web. This goes back to old text written in the Middle Ages (great ideas are often forgotten). I find rooty soil from the forest. If you innoculate your field with forest compost from varied sources locally, you personally scrap up, it will help yields.  

The mycorrhizal fungi will create a symbiotic relationship with the plants. One example is, that they will preserve water requirements in exchange for carbohydrates. 

Bacillus amyloliquefaciens (BAA) helps prevent root rot and nitrifying organic matter also prevents or inhibits pathogens. If you feed your soil and the probiotic nitrifying bacteria are prolific then you do not need to fertilize with anything else and preliminary empirical evidence shows it outperforms conventional methods. My point is to work with rhizobacteria (PGPR) as your fertilizer. The nitrogen cycle of converting, N4 to N3 is a foundation for plant growth. Nitrifying organisms convert naturally found ammonia to nitrate compounds absorbable by the roots. This is found locally and in healthy soil.

In addition to the functions of IMOs to convert an unusable form of nitrogen to a usable form of nitrogen, they assist in the absorption of the minerals. Life depends on life in a symbiotic way. Some will even sequester nitrogen from the atmosphere like Azotobacter, Beijerinckia, and Clostridium.

When you go down the road of unsustainable synthetic, this will dampen the ability of plants to establish this natural symbiosis and become reliant on exogenous inputs.

Concentrated soil amendments – I personally do not even use singular organic amendments like a bone meal (for phosphorus) or Potash (for potassium), as I like using complete elements like manure or green manures which are balanced with the idea of feeding the soil generally. However, you can and I postulate you will get good results. My growing philosophy is to let the microbes do the work, and build a balanced food went. Yes, singular amendments could increase yields, as P and K increase the size of sweet potatoes, however, growing, like life, is more an art than a science.

Insects – I squash insects and leave them on the plants as this sends a signal to others insects to stay away.

Urea (Human) – Urine is high in nitrogen, trace minerals, and growth stimulants. It needs to be mixed with a medium like compost for dilution. Literally, pee on your compost or soil and then apply with a shovel (people always did this, see the Revolutionary series “Turn” Abraham does this). 

Have you ever noticed how bright and shiny the packaging is for soil amendments? They will charge a lot for packaging. Better is to use free sustainable resources in your area. I use seaweed, you might use leaves.

A note on tarping – I do use tarps at times to clear large fields. Tarp a field and two months later you will have a few weeds that you can easily clean up. This is one of the easiest ways to start a no-till garden. Alternatively, you can put cardboard over a field and cover it with compost, companies in the area deliver this by the truckload cheaper than you can buy retail if it is a large area. The pricing for soil delivered in my area is about $250 for what would be about 170 bags or about $1.50 a bag, but you get a large field covered. Then innoculate with IMOs.

Crop rotation

I do rotate my fields and grow cover crops. In Florida, for example, I use the following: cowpeas, sunn hemp, bulldog alfalfa, winter peas, and dixie clover. Cowpeas are the easiest and fix 200lbs of nitrogen and acre and suppress weeds and provide food. Next, mow it or bring animals on there for manuring. I have not been rotating crops lately as I have been adding external amendments like seaweed and shells collected from the beach and letting the chickens do the work. People thank me for collecting seaweed that overruns our shores; they think I am part of beach clean-up and I do, I remove plastics I find.

Do not know what to do? Feed the soil organically with sustainable local resources you can find. Your sweet potatoes will know what to do themselves.

This post I will continue to update. I am currently working on a Ph.D. in economics, which takes priority, but I wanted to put something here as a resource.

Contact me with questions or corrections and ideas. 

Continue reading to the end as there is a comic one of my kids made.

What are Sweet Potatoes

Kingdom: Plantae

Clade: Tracheophytes

Clade: Angiosperms

Clade: Eudicots

Clade: Asterids

Order: Solanales

Family: Convolvulaceae

Genus: Ipomoea

Species: I. batatas

Binomial name

Ipomoea batatas

Ipomoea trifida is the closest relative.

batata

camote

kamote

apichu

kumara

Ipomoea trifida

Orgin: Yucatán Peninsula

My name is Mark Biernat I have been growing sweet potatoes professionally for many years. I also live near large sweet potato farms and exchange information about growing techniques. In contrast to the methods used on these farms, I have chosen another route. I am a small-scale organic grower. By growing sustainably I can grow more efficiently. There is a lot of information out there, based on speculation or generic generalizations. This information on how to plant and grow sweet potatoes is based on my experience so you can grow Ipomoea batatas in a way suitable for your context so you can produce large tubers rich in nutrients and flavor. My main point is to work with the native soil in your area and supplement only if needed, as native soil will be teeming with life. For example, if you fertilize I recommend organic amendments because they are sustainable. This can include compost, cow manure, seaweed, forest soil (rich in mycorrhizal), or alfalfa pellets (rich in triacontanol). However, no fertilizers are needed if you work with rich local soil as the beneficial organism suited to your climate. Most important is to invent your own methods with these indestructible plants as Sweet potatoes are easy to grow.

Ready to try my sweet potatoes? Go to my Martian Potato shop.

Thank you.