Sweet Potatoes: Mega-crop Container Gardening for Small Spaces

Sweet Potato Plot Survival Food

In this installment of our high-yield small-space gardening, we will look at two different types of containers and grow what will hopefully be copious amounts of sweet potatoes.  This is the perfect blog if you have limited growing space, poor quality soil in your area, or if you are confined to just a balcony off an apartment.  With the addition of a grow light or good placement by a window, you can bring a non-draining container inside, allowing you to grow even during the winter months.  There’s lots to explore here, so let’s get digging…

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WHAT YOU WILL NEED

There are two types of containers we will be building and testing out here.  The first has drainage holes in the bottom and may be problematic if your dirty water drains off a balcony, but it is no problem if you plan to simply set the pot outdoors.  The second is a self-contained system that kind of marries hydroponics with traditional container gardening while recycling all those plastic bottles.  This second method creates a reserve of water at the pot’s base and has been great at keeping the soil moist through our harsh summer heat waves.

For the container with holes, westarted with a 40-gallon, Low-density polyethylene (LDPE) water trough from Tractor Supply Company.  This container is 40 by 27 inches with a depth of 13 inches.  These come in many sizes and shapes, but the 40-gallon version we felt best matched the space we would have available in an apartment setting.  You will also need a drill, drill bits to make both small and medium-sized holes,  rocks and pebbles or chunky bark-like material, and some quality soil.

For the non-draining container, you may need a contractor-grade trash bag, and you will need a length of PVC pipe and multiple plastic bottles like gallon milk jugs and water bottles.  You will also need the drill and soil, but you will require less soil with this method, as the bottles will displace the soil and result in a lighter and easier-to-move pot.

CONSTRUCTING THE POTS

For the large trough, construction could not be more straightforward.  We flip it over and drill several small holes in the bottom to allow water to drain properly.  Some of these tanks and troughs come with a drain hole already built into them.  If that’s the case for you, skip this drilling step, as you can simply keep that drain hole open to let the excess water flow out of it.  This container will give me eight cubic feet of growing space.  A bountiful harvest could be around 30 pounds of sweet potatoes. We could have gone larger, but this container would have worked on the smallest apartment balcony we have ever had, so we wanted to emulate that grow space.  We will be using two here with two different types of sweet potatoes.

We put about twenty across the bottom with a 1/8th or 3.18mm drill bit. The number of holes doesn’t really matter. You don’t want too many holes because you want to keep the container’s structural integrity.  With your holes drilled, flip it over and add a thin layer of rocks, pebbles, or chunky materials.  Here I am using some chunks of bark from a terrarium.  The larger material will keep the finer potting soil from running out of the bottom.  We have also seen people use window screening material for this purpose.

With a thin layer of the chunkier material down, add the potting or garden soil you will be using.  Fill it to around an inch or two from the top and pack it down with your hands.  It will sink down and compact over time.  That’s it.  You are ready to plant your sweet potato slips in this container now.

For the second pot, we will create a self-watering system.  We’re using an old 17-gallon utility bucket that has started to crack and chip because of outdoor exposure.  It’s still viable as a container, but we will line it with a construction-grade trash bag to keep it water-tight.  With such a small container and the displaced area filled with the bottles, we will only get about two cubic feet of growing space.  For sweet potatoes, we can plant a maximum of 2 shoots.  However, there’s plenty of soil for other plants, so this method is excellent for tomatoes, peppers, and even amaranth or sunchokes.

For the water bottles, place them around the bottom with the lids on them, and arrange them so you have no free space where they can tip over.  For all the bottles but one, you will want caps.  You will insert the PVC pipe in one bottle, making watering and fertilizing the roots easy.  With the bottles placed, remove them and drill holes in them about 6 inches from the bottom.  The uniformity of the height of the holes from the bottom does not need to be exactly correct, but you want them to be around the same height generally.  For this, we are using a 5/8ths inch spade bit to give me a bigger hole, but you can really use any large bit.  We will also drill a hole or two on the angled top to allow the water and roots a way into the water reservoir.  We will also put a tiny hole in the lids.  This will serve the same function.

With the holes all drilled, we line the container with the contractor-grade trash bag.  These are sturdier and slightly thicker than regular trash bags, but any trash bag will do since the walls of the container support it.  We have seen some examples where people grow tubers just in trash bags loaded with dirt.  That can work, so long as the plant enjoys wet and hot roots.  In Southern California, we get too much harsh sun and too many critters trying to get to the wet soil for this method, in my opinion.

With the container lined, place your water bottles upright into the bottom.  In the one without a lid, you will insert your length of PVC pipe.  Now place your soil on top.  There’s no need for pebbles, rocks, or chunky filler because there’s no chance of your soil running off.  Pack it down well and shake it to allow the soil to go all the way down between any air pockets between the plastic bottles.  One real positive of this method is the ability to add fertilizer directly below the plant for the roots to take up, so we will just use one small packet.  We drizzle the top with water to get it to compact a little more. Then we can add water directly to the PVC pipe.  You don’t want to overwater or place this in an area that gets too much rain because your water doesn’t have an opportunity to run off.  You can add up the total area of the bottles you use to get a rough idea of how much water to add to fill the space to around the halfway point.

Your plants will find the water with this method.  That’s what roots are for, but you don’t want your plant swimming in the water and constantly soaking.  To this container, we will add just one shoot that we sprouted off an organic sweet potato we bought at the store.  Before we go into that, we want to show you a similar pot where we didn’t use this plastic bottle method.  You see, the plants are dry.  The soil is dry.  With the water source at the bottom in this water bottle method, the soil stays well hydrated.

One huge advantage to this container method is the ability to move the plant to whatever piece of your yard has the right amount of sunlight and the best growing conditions.

THE SHOOTS

Sweet potatoes are planted from offshoots, not seeds.  Sweet potatoes are a viny plant.  Wherever they touch the soil, they can take root and make more tubers at that location.  Over this last year, we have tried several different sprouting methods.  The method of burying them halfway in soil wasn’t very successful for us.  The process of putting toothpicks in them and soaking them in water like you might an avocado pit was 50% successful. We used two sweet potatoes and got one to give me one shoot.  We tried it with Tumeric as well, and that wasn’t successful.  If you try to get your own shoots from store-bought sweet potatoes, ensure they are organic, as non-organic may be sprayed with a sprout-inhibiting chemical.  If you buy them organic, you can sometimes get a spontaneous shoot to develop.  If you moisten that or put it halfway in damp soil, it will likely grow for you.

We wanted different varieties than at my local stores, so we ordered shoots from a well-known agricultural operation in Missouri.  We will plant a Korean Gold variety in one container and a Myanmar Purple in the other.  As an experiment, we placed them in two different sections of my yard, both with partial shade.  We came to realize that the placement for these didn’t matter as much as they enjoy the full sun, so when they were hardened off well enough, we put all the containers together as if they were all huddled on a patio.

Each shoot will yield between 3 and 6 root vegetables.  If you wait long enough, 120 to 150 days, you will have massive sweet potatoes that are bigger than anything you will get in the stores.  So, when you plant sweet potatoes, you want at least 90 days before your first frost.  If you get hit with a frost, the plant above ground will die off, but the sweet potatoes underground will be fine.  You can winter over the vines by gently turning them back into the soil and applying a thick layer of mulch.  This will keep the plant from freezing and provide you with yearly harvests.  Because these are above-ground containers, you may want to move them into a garage space over winter or heavily mulch the top to keep the vines from freezing, as they will lack the regular insulation of the protective ground.  

We will do a follow-up video to show you the harvest with this method, and these shoots we are planting here will be at the 120-day mark around Thanksgiving.  Because we don’t fear frost here, we will only harvest some then and let the rest continue to grow in size for another 30-days.

WHY SWEET POTATOES

We picked sweet potatoes for a couple of reasons.  First, it’s not an actual potato, as it isn’t in the nightshade family.  It’s actually in the morning glory family, so you may get some lovely flowering vines from them, though flowering is rare.  Unlike regular potatoes, sweet potato leaves are edible.  They taste like mild spinach and can be sautéd, added to stir fry, soups, or salads. The leaves are an excellent source of antioxidants and contain high levels of vitamins A and C and riboflavin, thiamin, folic acid, and niacin. Sweet potato leaves also provide impressive amounts of fiber, along with calcium, magnesium, manganese, zinc, copper, potassium, and iron.

The second reason we went with sweet potatoes is the high yield.  We can get multiple pounds of food year after year.  Finally, the sweet potato is super easy to grow and can come back yearly.  Sweet potatoes can be grown in any fertile, moist, nutrient-rich soil.  Pests are best managed with organics like diatomaceous earth and neem oil.  Everywhere the vine touches the ground is a potential new sweet potato.  The vines can be trellised or can be tended to and stacked upon themselves in an effort to contain it.  This plant will take over a large area if the soil is good and the conditions are right, so if you plant them directly into the ground, ensure it’s far enough away from your other vegetables.

This plant can also be grown very easily indoors, so long as the natural light from a window is sufficient.  The vines will get long and can be laced around windows.  The harvests will not be as impressive, but it can be done. We put this prepper plant up there with the sunflower, sun choke, purslane, and Amarnath.  You will be glad you are growing it.  At the very least, growing just one container like this will save you $100 or more yearly.

Subscribe to this channel to be notified when we harvest these sweet potatoes.  Perhaps the only drawback to sweet potatoes is that you must cure them by holding the temperature at around 80 to 85 degrees and with a humidity of approximately 85%.  This sets them up for more extended storage by healing any cuts or bruises.  Curing will also bring out the sweet potatoes’ sweeter flavors as it converts the starches to their smaller chain sugars.  We will do that and walk you through that process in the follow-up blog to this one.