All about plant fertilization

How and when to fertilize sweet potato


Sweet potato, or by its scientific name, Ipomoea batatas, is an evergreen climbing plant that is grown annually. Although it has its origin in America, today it is cultivated throughout the world. Its popularity is given by its edible tuberculous root. It has many uses in the kitchen, being able to prepare delicious dishes. In this article we will see everything about fertilizer for sweet potato, how and when to apply it, what types to use and some of the key care to make it grow healthy and strong.

Curiosity: it is proven that the sweet potato originated long before the human being, at least 800.000 years ago. Furthermore, some scientific studies have concluded that the early presence of sweet potato in Polynesia may show pre-European ties between Americans and Polynesians, contradicting official history.

1. What is the meaning of the three numbers on any package of fertilizer?


Every time you start doing a task that you don’t know much about, concepts appear that you don’t know their meaning. Some may be more important than others, and when it comes to fertilization NPK values ​​are something you should know if or if.

NPK values ​​are those three numbers that characterize any inorganic fertilizer you can buy at a nursery. If you don’t know what it means, you may end up fertilizing with something harmful to your plant.

Fertilizer for sweet potato
Sweet potato

You may have noticed that there are countless combinations of these three numbers, each representing a different type of fertilizer. There are 20-20-20, 15-10-15, 18-46-0 and much more.

But don’t worry, understanding what NPK values ​​are all about is more than easy. They represent the percentage value of the three main micronutrients that plants use. These are nitrogen (N), phosphorus (P) and end in potassium (K).

Let’s develop an example so that everything becomes clearer to you. Suppose you bought a 10-pound package of fertilizer 15-9-12. This means that 1.5 pounds of the total is nitrogen, 0.9 pounds is phosphorous and 1.2 pounds is potassium.

Pretty simple, right? Once this is clear to you, we can continue with the posting. 😉

2. Feeding your sweet potato


Although fertilization is an important point in the development of a crop, especially an intensive crop like sweet potato, only with fertilizers can a plant grow. You need other foods like sunlight, water, soil and various basic care.

We will start by looking at some essential tips for a good cultivation of your sweet potatoes, and then we will delve into the main topic, fertilization.

2.1 How to grow

We do not list these 6 cares in order of priority, each is as important as the other. Keep in mind that if you do one of these cares incorrectly, or don’t even do it, your plant may have trouble developing. Therefore, read each point carefully and apply what you have learned responsibly.

2.1.1 Climate and plantations

Although there are many varieties of sweet potatoes in general, they all need a climate with plenty of sun and humidity. It’s also worth noting its low frost resistance.

To select the planting time, note that prolonged periods of temperatures below 15 ° C stop growth. Due to its sensitivity to low temperatures, it is necessary to wait 2 weeks after the last probable frost date for planting, when the soil has a temperature of at least 14 ° C.

Planting should preferably be done on earth boards approximately 30 cm high, with each plant about 35 cm apart.

2.1.2 Spread

The most common is to do it with cuttings. They should be cut when the plant is at the harvest point, being an ideal length of 30 or 40 cm.

After cutting the boxes, the leaves located in the first 10 cm of length should be removed, this is the section that will be buried in the ground. Always keep in mind to look for healthy plants, free of any disease to select cuttings.

2.1.3 Irrigation

Sweet potatoes need well-damp soils, especially in their first days of planting, which guarantees a better rooting of the cutting.

During the five months that its cultivation lasts, three or four irrigations may be sufficient. Although for obvious reasons this will always go hand in hand with the weather, if it is very dry you will need more watering.

In intensive crops, the most common is the use of irrigation flooding the furrows. In case of gardening, other types of irrigation can be applied.

2.1.4 Plagues and diseases

The most common insects and diseases are those caused by fungi, viruses and bacteria. Soil fungi are very harmful, causing spots or total rot of the plant.

In intensive crops insecticides and fungicides are used to treat these pests and diseases. Although in smaller crops such as those you can do at home, you can carry out more ecological management, although with much lower yields.

Whatever the case, it is important to carry out regular checks to detect any problems. It is essential to take action on time.

2.1.5 Harvested

Since sweet potato growth will continue as long as temperatures are appropriate, harvesting can be done gradually as sweet potatoes grow to a suitable size.

In other words, you can harvest the bigger sweet potatoes (remove them carefully) and then cover the furrow again so that the others keep growing.

2.1.6 Soil and fertilization

The best adapted soils are sandy, although it is capable of adapting to any soil that has good drainage capacity. The ideal pH is in the range of 5-7.

In general, it is always good to add new nutrients to the sweet potato by applying fertilizers. Regarding this point, we will develop it in depth in the following sections.

If you are reading this post, you will probably be interested in learning about fertilizing these other plants.

2.2 Nutrient most required

Each plant has different nutrient needs compared to the other, which is why there are so many types of fertilizers. As for sweet potatoes, although they need the primary NPK micronutrients, they do not need it in equal amounts.

Potassium is the essential element for development of many of their life processes. Sweet potato absorbs large amounts of this element, being of great help in the thickening of the tuberiferous roots.

On the other hand, if we compare the needs of potassium, nitrogen and phosphorus, they are micronutrients that you need in less quantities. Despite this, it can be assured that phosphorus is of great help in increasing the average weight of the crop.

Keep in mind that these needs will always be linked to various factors, such as soil characteristics, preconditions, environmental factors, etc. If it is an intensive crop, you must be clear about all those factors if you are looking for good yields.

2.3 Best fertilizer for sweet potato

As you can imagine, the most recommended sweet potato fertilizer goes hand in hand with the plant’s nutrient requirements. In contrast to this, and to better control micronutrient ratios, inorganic fertilizers with certain NPK values ​​are recommended.

As we have already developed in detail what the NPK values ​​are at the beginning of the post, there will be no problem for you to understand (any questions go back to section 1).

As we said, the one that needs the most is potassium, consequently a 1: 2: 3 balance is recommended between the three micronutrients. In other words, for every part of nitrogen there will be two parts of phosphorus and three parts of potassium.

Knowing to look for fertilizers with a ratio of 1: 2: 3 is that those with a mix of 5:10:15 or 9-18-27 are ideal for sweet potatoes.

In addition to inorganic fertilizers, it can also be combined with other more natural ones such as compost. These are mainly used to improve soil characteristics before planting.

Another addition that can be done before planting is lime, with which you try to vary the pH of the soil. This should always be done in conjunction with relevant soil studies, remembering that the ideal pH is between 5-7.

3. How and when to fertilize sweet potato


First of all, for intensive crops it is important to carry out soil studies that allow us to know the pre-existing nutrients in it. Once these data are known, you can start with a 1: 2: 3 NPK Proportional Fertilizer (as seen in the previous section) before planting. This will ensure a good development of the plants in their early stages.

When the soil is neither too poor nor too rich in nutrients, the normal amounts of fertilizer for sweet potato are generally around 1.25 to 2.25 pounds per foot. After this fertilization, you can wait about four weeks to carry out another fertilization, always with these proportions where potassium takes precedence over other nutrients.

If you are going to use natural fertilizers to improve soil characteristics, keep in mind that these can be a vehicle for causing diseases, of which the sweet potato is quite sensitive. For this reason, the application of horse guano fertilizers is not recommended.

If cultivation is not intensive, but you are doing it in your garden, you will generally not do a soil survey. Given this, it is better to place little fertilizer than to place too much. Excessive placement brings irreversible problems.

3.1 Most common problems in poor fertilization

If bringing the fertilizer in the proper proportions during cultivation brings many advantages, you can imagine that not doing so causes certain problems. Among the most common we can list the following:

  • Applying insufficient amounts of potassium will result in overly elongated and malformed sweet potatoes.
  • If it has been fertilized with excessive amounts of nitrogen, it will be possible to notice that the plant will develop too much its foliage, but not its roots. Therefore, production will not be good.
  • On the contrary, if the amounts of nitrogen are low, the results will be the same, a bad harvest. Although in this case the foliage will not develop excessively.
  • The application of insufficient amounts of phosphorus can cause a harvest of few tons, something that will be especially noticeable in intensive crops.

Like these four problems, several more can be listed, although these are usually the most common.

4. Maintenence and fertilizing sweet potato video


To finish the article, we selected a video from the GrowAndEatThis channel, which reviews many of the basic care and maintenance tasks that need to be done to grow your sweet potatoes. I have no doubt that it will be very useful to see it. 😉

Well, with this we have reached the end, I hope you have no doubts about how and when you should fertilize your sweet potatoes.

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