Fertilising will help the pumpkins put on the extra weight and size to make it a great giant pumpkin.
What type of fertilisers could you use?
There are two ways of thinking about providing your pumpkin with nutrients as it grows, the traditional fertiliser kind of way, or going fully organic. Either way provides nutrients to your plants, and even a mixture of both may be used as the season goes on.
The traditional types
These are mainly made up of Nitrogen, Phosphorus, and Potassium or NPK
The organic types are usually derived from nature and a lot of them can contain fish and seaweed minerals.
Provide what the plant wants and needs, and slow and steady
The trick to any fertiliser is to provide the plant with what it needs, this can be worked out from just understanding your plants to getting foliar tests done. Slow and steady is also a key, not overdoing it and causing to much stress on the plant is what you are aiming for here.
Most of what the pumpkin requires can be met by using a water soluble plant fertiliser, once or twice a week. To start off with your best bet is to use a fertiliser that has a good amount of nitrogen in it. Once the flowers appear one with a high phosphor content will help, and once the pumpkin has started growing changing to a fertiliser with a high potassium content wont hurt the plant.
You don’t need to be a science whiz to understand the numbers on the fertiliser. The three main chemicals are Nitrogen, phosphorous and potassium, (or NPK) these are usually shown as 3 set of numbers like this: 5-10-5 which shows the percentage of each chemical.
In the early stages of growth of the giant pumpkin this is what you need to make sure you have, as it helps with leaf, root and vine growth, and will result in a very green plant. As well as being very good for the plant, it can also do the most damage to the plant, so avoiding contact on leaves and vines is always a good idea.
Too much nitrogen can also reduce or delay the amount of flowers that are present, if this seems to be the case just stop adding the fertiliser for a week or two.
Once the plant moves to the fruit setting stage, switching to a fertiliser with a high amount of phosphorous is a good idea, a good ration at this time is 5-10-5, or 5-15-5. If you cant really be bothered by changing fertiliser all the time, this is a good ratio to use all year round.
Phosphorous helps with healthy root growth, fruit setting and development. Phosphorous is more forgiving then nitrogen so if too much is applied it wont burn your plant. Another characteristic is that it is less water soluble which also helps if too much is applied.
This is what promotes fruit growth. Once the fruit is set, switching to a higher potassium fertiliser or supplementing with extra potassium like phosphorous. It will not burn your plants.
The only downside to potassium is that in combination with good sun, good water supply and good soil, it can cause your pumpkin to grow so fast that it can out grow its skin and split or explode. So taking it easy in the early stages of fruit development is a good idea.
The main thing to remember when fertilising is that slow and steady wins the race. When you feel the urge to fertilise, remember this, and don’t go overboard.