Potato plants will grow in many different types of soil but thrive in well-drained soil or sandy loam. The best pH for potatoes is between 5.5 and 6.0, so it’s a good idea to test the pH of your soil. But this is not enough. You also need to prepare the soil before you plant and then feed your potatoes while they grow.
Both adequate water and fertilizer are essential for healthy potato plant development. You will, of course, need to prepare the soil, adding fertilizer and amendments before planting potatoes. But potatoes need lots of nutrients throughout the growing season to produce new growth and develop quality tubers.
What is the best food for growing potatoes?
As we’ve said, potatoes need lots of nutrients throughout the growing season. Most importantly, you need to source the best fertilizers for potato growing.
The folks at Oregon State University’s Extension Service explain that potato plants need 16-17 mineral elements for maximum yields and quality. These are nitrogen, phosphorus, sulfur, calcium, magnesium, potassium, iron, manganese, molybdenum, copper, boron, zinc, chlorine, sodium, cobalt, vanadium, and silicon.
But don’t panic. Most of these are only needed in very small trace amounts, which most soils already contain.
When you buy fertilizer for any plants, you need to be aware that most contain the same three major elements: nitrogen (N), phosphorus (P), and potassium (K). Some have sulfur in them as well.
Potatoes need nitrogen to grow nice, green, healthy leaves and phosphorus for tuber production. Potassium plays a key role in general plant health, and sulfur helps with the uptake of nutrients.
Different Products Provide N-P-K in Different Ratios
Different products contain the three essential elements in different ratios. So, if for instance, you see 10-20-20 on the label, this means it contains 10% nitrogen and 20% phosphorus, and 20% potassium.
You don’t have to be a scientist to use the correct fertilizer or plant food. But it’s interesting to know that while nitrogen is expressed as an actual percentage, while the other two aren’t.
Phosphorus content is a percentage of P2O5 – the O being oxygen. And potassium (K) is a percentage of K2O. These elements are too reactive to be used on their own.
Another factor is that you need to feed according to the soil you have. Since soil conditions vary across the U.S., you will find that different university extensions recommend fertilizers with different ratios of N-P-K.
Assuming you have done a soil test, the University of Georgia Extension recommends following the guidelines the test provides. But in addition, they recommend adding 1.5 lbs of 10-10-10 once the above-ground vines from the potato plant have spread out about two weeks.
The experts at the University of New Hampshire Extension suggest fertilizers with a higher middle number (phosphorus) than the first number (nitrogen). More specifically, they suggest a 5-10-10 nutrient combination whether you’ve had a soil test or not.
If you want organic nutrients, they suggest that you use a combination of kelp and bone meal, fish emulsion, and greensand. Or you can simply buy organic fertilizer.
When to feed potatoes?
A team of horticulturists from Michigan State University’s Department of Potato Breeding and Genetics has developed A Guide to Growing Potatoes In Your Home Garden. It provides invaluable information about every aspect of how to grow potatoes, including soil preparation.
Their suggestion is to rototill about 2 lbs of 12-12-12 fertilizer per 50 feet of each row. Then, a week after the plants emerge out of the ground, apply ⅓ lb of urea fertilizer per 50 feet of row. Repeat this after 4-6 weeks.
Note that the urea fertilizer should not be worked into the soil. Instead, water the soil thoroughly to encourage the fertilizer to soak into the soil and feed the roots.
They warn against amending the soil with manure or lime when you are growing potatoes. This is because they increase the risk of common scab disease.
If you need to amend the soil with lime or manure, wait a year before you grow potatoes.
The University of Minnesota Extension suggests side-dressing your rows of potatoes about four weeks after planting potatoes. Hill up the soil around the plants and add a small amount (0.15 lbs) of actual nitrogen per 50 feet of each row.
Repeat two weeks later.
The Texas A&M University System’s Extension Service advises adding fertilizer when the tubers are forming. This, they say, is when the plants are between 6-8 inches tall.
How to feed potatoes?
Sometimes fertilizer is dug into the ground. Other times, it is simply applied to the soil and then watered so that the fertilizer moves into the root zone.
The TAMU Extension suggests applying one cup of fertilizer for every 30 feet of each row alongside the plants. Do this when they are about four inches tall.
Potato Growing Tips for Better Yields
Before you start growing potatoes, you need to be sure that the soil is well prepared. We’ve mentioned that the best soil pH in which to grow potatoes is between 5.5 and 6.0.
If the pH is higher than 6.0, it tends to increase the risk of severe common scabs. This is a disease that attacks tubers and forms raised or pitted corky areas.
Getting the pH right will definitely help to get better yields.
Of course, you also need to start out with well-fertilized soil, which we have already mentioned.
Unless you are completely new to growing potatoes you will know that we don’t ever plant seeds as such. Rather, we plant seed potatoes.
Seed potatoes are potatoes with an “eye” or “eyes” that emerge from it to form a new plant or plant. You can slice off a piece of potato with an eye and plant it.
However, unless you are happy to experiment and are not relying on a decent potato yield, it is advisable to buy certified seed potatoes.
Unfortunately, planting uncertified seed potatoes can result in producing potatoes that are infected with viruses.
Another thing to be very aware of is that potatoes are very sensitive to moisture in the soil. If you can maintain consistent soil moisture you will get a better yield.
Shallow cultivation of potatoes is best for weed control. And, of course, you need to be aware of the many pests and diseases that can attack your plants and deplete your yield.
We aren’t talking about pests and diseases in this post, but the Michigan State University guide has a wealth of information on this topic. They also provide lots of other growing tips.
What helps potatoes grow bigger?
In a nutshell, proper fertilization and adequate watering will help to ensure that your potatoes grow bigger. It really is that easy.
It’s not difficult to grow potatoes, but it is essential to have good-quality soil with a suitable pH. It is also extremely important that the potatoes are well-fed with a suitable fertilizer and watered regularly.
Most university extensions have online information about growing potatoes in their area. While the basics remain the same, there are differences often based on climate and common soil conditions.
We have provided some examples. But if you need more guidance on how to grow potatoes and feed them, contact the extension at your local university.