Fertilizing Pumpkins For Huge Fruit

Pumpkins Two

Fertilizing Pumpkin For Plant Health And Fruit Growth

Pumpkins are extremely heavy feeders. They thrive in the rich soil you provide, along with lots of manure and compost added into the soil. They grow even bigger, when you add fertilizer into the equation. Determining what fertilizers to apply, and how often, can be cause many gardeners to roll their eyes.

When fertilizing pumpkins, many factors come into play. It is important to consider current growing conditions of soil, type of soil,  pH levels, amount of rainfall, and more. Finding the perfect formula for your pumpkin patch, sometimes comes down to trial and error.

How to Fertilize Pumpkin Plants

Confused over what fertilizers to apply, when, and how often? What do all these fertilizers do anyway?  And, did you know that the wrong fertilizers, or over application, can harm your plants?

We are here to help you in this complex area.  Hopefully, we will not overwhelm you with the technical side of pumpkin growing.

Fertilizing Pumpkins - Learning the Chemistry

You do not need to be a Chemistry major to understand the basics of fertilizers for your garden. Fertilizer packages and containers display the three major chemicals on front of the package. It looks like this:


5 – 10 – 5

And it stands for: Nitrogen – Phosphorous – Potassium

If you recall High School Chemistry class, they are abbreviated as “N”, “P” and “K” respectively.

On fertilizer packages, these numbers are displayed (I.e.. 5-10-5) to show you the percentage of  N-P-K in the fertilizer. Depending upon the growth stage of your pumpkin, you should seek higher or lower levels of these chemicals.

Nitrogen Apply higher concentrations of Nitrogen in the early growth stage. It provides the “fuel” your pumpkin plant needs for leaf, root, and vine growth. High levels of nitrogen result in a lush, green plant. Of the three major chemicals, nitrogen can also provide the most damage, as it can burn your plants. Avoid direct contact to leaves and vines. If you have ever put too much fertilizer on a section of lawn, and see it burn out, you already understand the effects.

Too much nitrogen also can reduce or delay the emergence and the number of flowers and fruit. If your plant is  growing well, and is a healthy green, but yet has no flowers, stop adding nitrogen for a week or two. As the plant takes in less nitrogen, it redirects it’s energy from plant growth to fruit set and development. Also, extremes of nitrogen can cause wilting(due to burning) of your plants.

Phosphorous As the season moves towards the flowering and fruit set stage, switch to a formula higher in Phosphorous. 5-10-5 or 5-15-5 are common ratios. If you do not want to worry too much about what fertilizer to use, this is a good overall ratio for the entire year.

Phosphorous promotes root growth, flowering, and fruit set. Phosphorous is more forgiving, as it does not burn your plants . It is also less water soluble, so an over-application will not do major harm to your plant.

Potassium This chemical promotes fruit growth and health. After fruit set, you should either switch to a high potassium fertilizer, or supplement your feedings with extra potassium. Like Phosphorous, Potassium will not burn your plants. Over application however, along with all the other ingredients(sun, water, rich composted soil) can cause your pumpkin fruit  to grow so quickly that it outgrows it’s skin and splits or explodes. Take it easy early in the fruit development stage, especially if you are a new grower.

Now that you have enjoyed today’s science class lesson, go out and put it to work in the field. Remember, to avoid over application, and not to overlook the other essentials ……good soil and plenty of water.

IMPORTANTLY: Fertilization techniques are not unique to pumpkin growing. Use these same techniques on all of your vegetable and fruit gardens. There are some exceptions to the proportions. But overall a general fertilization plan will benefit all crops. For exceptions, you should research individual plants.

Nutrients and Minerals are important, too.

There is a wide variety of chemicals, sometimes referred to as “trace” elements that are hopefully in your soil. These minerals and “micro” nutrients each contribute to, and are essential to, plant growth. This applies to any plant growth whether it be a vegetable, a tree, a flower or weeds. Just read a box of liquid fertilizer, and you will see the chemicals and trace elements. Some of these are likely to be in your soil already. It all depends on what type of soil you have, whether these elements are readily soluble, and whether they have been depleted through years of growing. Look at micro-nutrients as multi-vitamins for your plants ,as that is exactly what they are. You take regular, daily vitamins for good health. Your plants need them, too.

Liquid Fertilizers:

Liquid Fertilizers are favored by almost all gardeners, regardless of what they are growing. We praise the glory of liquid fertilizers. It can be applied as a foliar feeding directly to the leaves, hand applied to secondary roots, and included in the water supply of drip or other irrigation systems. Most growers will go through a box or two each season. When growing giant pumpkins, many growers apply it every time they water.

Aside from cost(and it is not that much), liquid fertilizers have almost no downside. They include all the chemicals  and micro-nutrients needed for good growth. In addition, because they are in a water soluble state, they can easily be absorbed by the plant.

One limitation is that it is often difficult to find a mixture other than the normal average which is usually something like 5-10-5. If you want to stress one chemical over the other, it is hard to find a different mixture. Secondly, because it is dissolved in water it flows through the soil, and must be frequently applied.

Another important point is you should not rely exclusively on liquid fertilizer. Nothing beats a rich garden soil, supplemented with compost and manure. Gardeners should seek to continually improve their soil. Successful gardeners make this a regular routine.

Fish and Seaweed Fertilizers

Giant pumpkin growers (and many other gardeners), will attest to the value of fish and seaweed fertilizers. It comes in liquid form. Both are low in N-P-K, but loaded with organic micro-nutrients. Giant pumpkin growers use both of these regularly, both for foliar feeding, and applied directly to the roots.

 Fish and seaweed manufacturers say that regular use helps the plants to ward off plant disease.

More on fish fertilizer

More on Seaweed fertilizer

Find Fish and Seaweed Fertilizer

Fertilizing Pumpkins Through Foliar Feeding

Foliar feeding is the simple, but important process of feeding your plant through the leaves. Use a liquid fertilizer, and spray leaves and vines. Make sure to follow the directions on the fertilizer container. Do not use too much fertilizer, and mix thoroughly. Too much fertilizer can burn the leaves. Regular weekly, or more frequent applications will result in healthier, greener leaves.

After having been away on an extended trip one year, I began foliar feeding upon my return. A week later, my neighbor remarked at how green the plants had become since my return. He suggested that the plants had missed me. I agreed and did not  reveal my secret to him.

Practice foliar feeding regularly, beginning early in the season. You will be rewarded with much healthier and stronger plants. And, you will add pounds to the fruit.

Your Fertilizer Strategy

Now that you are armed with a little knowledge about fertilizers, it is time to plan your strategy. Here is a basic plan and template for you to use. Adjust it for your area and conditions ,as well as your personal experiences and experimentation ideas.

  • Prior to planting prepare a bed rich in compost, manures and nutrients.
  • Mix general purpose garden fertilizer into the soil before planting.
  • Apply foliar feeding once a week or more.
  • Apply dry fertilizer every two to three weeks.
  • Include liquid fertilizer in the water your feed your roots, as often as you desire.
  • Use fertilizers high in Nitrogen until flowers appear.
  • Switch to higher Phosphorous during fruit set stage.
  • Use high Potassium fertilizers for fruit growth.

Important: We strongly urge you to follow the manufacturers instruction carefully. Make sure you know, and follow, any safety precautions.

Tip for Inexperienced Growers: In your first year or two, simplify your efforts and look for a balanced dry fertilizer like 5-10-5. Apply it every two weeks, and thoroughly water it in. Apply liquid fertilizer as a foliar feeding. You will be rewarded for the minimal effort, and can get more “experimental” in following years.

Take notes and log what you applied, how much and the reaction of the plant. Diaries and logs are fun, and provide valuable information for future years for you and your friends.

Grower Secrets on Fertilizing Pumpkins

Every avid grower develops his own secret ingredients from fertilizer to preparation of the soil. Some will share their secrets, others will not. You will need to judge and evaluate the facts from the fiction.

A friend of mine overheard a grower at the bar who had had one or two too many. The grower said his secret to giant pumpkins was adding milk to the soil. My friend had a couple gallons of milk which was beginning to sour so he said “what the heck” and applied it to the pumpkins. All he got for his efforts was a sour smelling patch. Fact or fiction? I don’t know. But, if there is any truth to it, it is probably in the chemical composition of milk. Plants need calcium(a major element of milk) for root development. This sounds to me like the “root cause” of the growers’ secret.

Got one to share, write us below and we will post it along with your name or anonymously if you prefer.


Common Problems Fertilizing Pumpkins

Most problems with fertilizers occur with new and in-experienced growers. The biggest problem with fertilizers is over application. If you apply too little fertilizer, nothing much happens, including no burst of growth or green up of your crop. The danger lies in over-applying. Nitrogen in fertilizers can burn your plants, cause wilting and delay the flowering stage. Take it easy, take it slow and importantly, study the results.

Fertilizers, pH and Micro-Nutrients A must see at The Gardeners’ Net

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