Sowing and growing pumpkins in your garden or up a trellis is one thing; knowing how and when to fertilize your pumpkins is another.
The first thing to know when learning how to fertilize your pumpkins is that pumpkins have three distinct growth phases.
1. Pre-flowering stage 2. Flowering stage 3. Fruiting stage
Each stage has different requirements when it comes to the fertilizer that you feed them.
Once your seed germinates and the plant breaks through the soil, you’ll notice two oval shape leaves on the stem opposite each other. These are the cotyledons, and these give your baby pumpkin plant everything it needs to get started in the beginning.
The best thing you can do right now is provide your plants with a really good quality soil you can either make yourself or use lots of worm castings.
Once your seedlings start to grow and you’ve transplanted them into containers, or you’ve thinned them out if you’ve planted them in the ground, you’ll need to start feeding them.
Pre-Flowering Stage
It takes approximately 55 days for your vine to begin flowering.
During this time, you need to get the first stage fertilizer for your pumpkins: nitrogen.
Nitrogen is an element of chlorophyll, and all plants need chlorophyll to photosynthesize. The plants need to grow their trailing vines and their gorgeous great big leaves, and nitrogen helps to do that.
The best thing to do now is to check the macronutrients of your soil and if it is nitrogen deficient, add some BLOODMEAL (don’t confuse this with bonemeal). Bloodmeal is packed with nitrogen!
If you find during your testing that the plant is deficient in potassium and phosphorous as well, you can add a fertilizer that is 10-10-10 so that your plant prepares for stages 2 and 3 of its growing stages.
Just look for brands that are organic. Another organic option is fish meal.
Soil Test:
Before applying any fertilizer, it’s always a good idea if you can, to determine your soil’s nutrient levels. This will tell you if nitrogen is needed and in what quantity.
But it can be costly to keep testing as you need to send the soil away to be tested, so rather ensure you have a good healthy mix of soil when you start.
Initial Application:
When your pumpkin plants are in the early stages of growth and have several true leaves (typically after the seedling stage), you can make an initial application of bloodmeal. You can use a balanced organic fertilizer or bloodmeal specifically. Follow the recommended application rate on the product label or based on the results of your soil test if you did one.
Monitor Growth:
After the initial application, monitor the growth of your pumpkin plants. If you notice that they appear pale green or are not growing vigorously, it may be an indication that they need more nitrogen.
Additional Applications:
Depending on the growth rate and the visual appearance of your pumpkin plants, you can apply bloodmeal or another nitrogen-rich fertilizer every 4-6 weeks during the pre-flowering stage. However, don’t OVER-fertilize, as excessive nitrogen can lead to excessive vegetative growth (lots of greenery), at the expense of fruit development.
Watering and Environmental Factors:
Ensure that your pumpkin plants receive adequate water and are at least 6 hours of sunlight a day.
Adjust Based on Soil Test Results:
If you perform another soil test later in the growing season, you can adjust your fertilizer application based on the test results which will help you avoid over- or under-fertilizing your pumpkin plants.
How much bloodmeal/ nitrogen fertilizer should you add?
Read the directions on the packaging and rather err on the side of caution.
– Sprinkle the indicated amount of bloodmeal evenly around the base of each pumpkin plant, avoiding direct contact with the plant stems. Be sure to spread it over the root zone.
– After applying the bloodmeal, water the plants lightly to help the nutrients penetrate the soil and become available to the roots.
Remember that while bloodmeal is a good source of nitrogen, it’s essential to maintain a balanced nutrient profile for your pumpkin plants by providing phosphorus and potassium as well as I mentioned above.
What is an alternative bloodmeal – for example, if you are vegetarian or vegan?
Alfalfa Meal is a good option. This is a vegan fertilizer made from the leguminous alfalfa plant and has a rich nitrogen content.
If you are transplanting your seedlings, then mix this into the soil of the larger container you are transplanting into.
And lastly, you can also grow beans in the same container of your pumpkin plant, if you have space. Bean plants naturally put nitrogen back into the soil, but it is still good to add something else for an overall boost. Vermicompost, or worm castings, is another excellent option and you should have mixed this into your soil in the beginning.
Watch your plants and at around day 40/ 45, before the yellow flowers appear, you’ll need to stop feeding your pumpkin plants with nitrogen.
The Flowering Stage
The flowers will appear at around day 50 / 55 (almost two months after sowing).
Now you need to add phosphorous to your plants, which you can get from bonemeal. This helps provide the plants with the energy it needs to produce buds and fruit.
Bonemeal contains a healthy dose of phosphorous (the P in NPK that you’ll see on the fertilizer bags). Bonemeal has very little nitrogen and potassium. Simply sprinkle a handful around the base of the plant and gently work it into the soil. When you water it, the bonemeal will leach down to the roots.
Now cover around the base of the plant with mulch.
Watch the buds and you’ll notice male flowers opening first, followed by the female flowers. This is so that bees are attracted to the plant and start to include your pumpkin plants on their daily route.
When the female flowers grow and open, the bees should be buzzing around and will naturally pollinate your female flowers.
In addition, you can also provide your bees with other pollinator plants in your garden to attract them.
Continue to feed your plants with bonemeal every two to three weeks. If your leaves start to turn yellow around the edges, stop with the bonemeal or other phosphorous feed that you’re using. Too much phosphorus can inhibit the plant’s iron and zinc uptake.
Once you’ve got several small fruits developing on your vine, it’s time to channel some of your fertilizer focus to potassium.
Stage 3: Fruiting Time!
When the female flowers start to turn into pumpkins, continue with the phosphorous every couple of weeks but you’ll also need to add some potassium now too.
Potassium helps regulate the amount of water and carbohydrates stored in the plant tissues. It also stimulates the production of starch and protein in the gourds.
You can switch to a 5-10-10 NPK fertilizer that is high in both phosphorus, or potassium, or continue to feed your plant bone meal along with seaweed powder, which is another excellent source of potassium.
If you can, collect seaweed yourself, wash it off really, really well to remove the sea salt. Water the pumpkins with this once a week.
Your plants will show you if you’re doing anything wrong. If the fruit starts to split while it’s growing, you’re giving it too much potassium, so hold off on that for a while.
Talk to your plants daily, check out the fruit, and if you follow the above, you will have gorgeous, tasty, bright, fleshy pumpkins within 3 – 4 months.
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