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Fertilizing Sweet Potatoes: What Is The Best Fertilizer?

Sweet potato vines are easy to grow. However, if you want your root vegetables to produce a plentiful harvest, you’ll have to provide them with what they need. In this post, we’ll go over everything about fertilizing sweet potatoes, including when and how to apply fertilizers, which types to use, and some of the most important things to ensure that they grow healthy.

Now, let’s get started!

What Are The Best Fertilizers For Sweet Potatoes?

The ratio of 5-10-10 or 12-12-12 is the best fertilizer for sweet potatoes. The rule of thumb for this task is to pick produce that is low in nitrogen and high in potassium and phosphates.

Commercial fertilizers

When buying commercial fertilizers, be sure to check the packaging for the NPK ratio. Nitrogen stimulates the growth of new leaves in the sweet potato. Potassium and phosphates, on the other hand, encourage root development. Potassium and phosphates are more favorable to the growth of your crop since sweet potatoes are root vegetables that develop below the soil surface.

Organic fertilizers

When it comes to organic fertilizers, gardeners have more options. Here are some suggestions for your crop.


Sweet potatoes obtain most of their essential nutrients from compost. Choose a compost that is at least one year old and entirely composted.

Alternatively, ensure that your homemade compost has fully decomposed and does not contain any non-compostable materials. Sweet potatoes should not be grown in compost that is high in nitrogen, as it can lead to small tubers. Your crop can benefit from plant-based fertilizers or compost generated from low-nitrogen resources like leaf moulds.

Kelp meal

All plants obtain macronutrients and micronutrients from kelp meals. It improves soil and root development and overall growing conditions by providing more minerals.

Bone meal

Sweet potato plants require calcium from bone meals. This fertilizer can also counteract the effects of other soil changes. Bone meal contains calcium, promotes root growth, develops strong roots, and avoids blossom-end disease.

Epsom salt

During growth, apply Epsom salt to the soil to supply your crop with magnesium, which aids in the development of sweet potato tubers. For a more direct method, combine one tablespoon with one gallon of water and sprinkle straight on the leaves as a foliar application.


Seaweed is rich in potassium, phosphates, nitrogen, and magnesium, all of which are essential nutrients for plants. Water lightly and feed monthly with this option.

Schedule For Fertilizing Sweet Potatoes

Once you have selected high-quality fertilizers, it is important to plan the feeding schedule accordingly. The schedule differs based on the types of fertilizers you use.

Commercial fertilizers

Approximately two weeks after growing sweet potatoes in your garden, you may start feeding them. You can fertilize them every four to six weeks during the growing period. In this stage, three fertilizer dosages are sufficient.

Two to four weeks after growing sweet potatoes, you can move on to the second application of fertilizers as a side dressing. The side-dressing should be high in potash and low in nitrogen. Also, keep the fertilizer about four inches away from the young vines and three inches deep.

When sweet potato plants are young, liquid or water-soluble fertilizer is good. It may, however, burn your plants if it comes into direct touch with them. When the sweet potato plant starts to expand, it’s simple to apply fertilizers that you may dilute with water. Besides, if you use a hose-end sprayer, you may use water-soluble products during your regular watering routine, saving time.

Organic fertilizers

Before growing sweet potatoes, spread compost into the soil to provide the necessary nutrients for optimum sweet potato production. An early application of fertilizers in well-draining, rich soil might be all that’s necessary for the entire growing season. Apply from 2 inches to 4 inches layer of leaf mold or compost to the soil, then sprinkle it up to eight to twelve inches deep. Poor soils, such as rocky or sandy soils, require up to six-inch layers of compost because they have little organic matter.

A side dressing of leaf mold or compost should be six to eight weeks after the plants grow. It would be best to give your crop this treat in the middle of summer. This procedure provides a fresh supply of nutrients to keep the plant thriving for the rest of the growing season. 6 inches away from the plants, you can dig small two-inch furrows. Ensure that no growing tubers are disturbed before spreading the compost into the furrows.

When And How To Fertilize Sweet Potatoes?

The standard levels of fertilizer for these plants are roughly 1.25 to 2 pounds per foot if the soil is neither too rich nor too low in nutrients. After this treatment, you can wait about four weeks to feed your crop again, using the same ratios as before, with potassium taking precedence over other elements.

If you’re going to employ natural fertilizers to enhance soil properties, be aware that they might also serve as a channel for disease transmission. As a result, you should not use horse guano fertilizers. It is preferable to go for a small amount of fertilizer rather than a large amount. The excessive application causes long-term damage, such as malformed sweet potatoes.

When Shouldn’t You Fertilize Sweet Potatoes?

Do not feed your crop at the planting time. It doesn’t require many nutrients during that time. If there is too much nitrogen, you will get leafy plants instead of big sweet potatoes. Also, around three weeks before harvest, cease fertilizing them. In most cases, three fertilizer dosages are sufficient during the growing season.

Sweet Potato Fertilizer Problems

You may encounter two common problems when you grow sweet potatoes: nutritional imbalance and improper soil condition.

Nutritional imbalance

If you have a plant with lush foliage, you might expect it to yield a massive harvest of big sweet potatoes. On the other hand, this sign might indicate that you over-fertilized the crop with nitrogen, resulting in a lot of surface expansion but little or even no root development. Applying too little nitrogen might result in stunted, weak development. The outcomes are not ideal when you harvest sweet potatoes.

Soil issues

For optimum development, your crop demands fertile soil conditions, particularly soil temperature. Warm, green sand or clay soil is perfect for them to flourish on.

Frost sensitivity is a problem for some plants. Before planting sweet potatoes in the soil, wait until the soil temperature rises to at least 65°F. These vegetables prefer a pH range of 4.5 to 7.0, although they aren’t sensitive to pH levels as long as they are not too acidic. When it comes to soil preparation, you can apply some lime to raise the pH of the dirt or sulfur to lower the pH of acidic soils.


Proper fertilization is one of the determinants of the success of your harvest. Thankfully, you have a lot of choices to offer your crop the best conditions. We have shared with you all the necessary tips for cultivating sweet potatoes. If you need any further information about gardening tips, please feel free to ask. Thank you for reading!

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Kelly Lawrence

Kelly Lawrence

Kelly Lawrence is the CEO of Swipe Garden. Over 10 years in the writing and passion for gardening, she brings a wealth of expertise and creativity to the world of gardening. Kelly Lawrence has cultivated a community of plant lovers, making gardening accessible and enjoyable for all.