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Deer Park, WI

The old adage in our circles suggests that nitrogen after pollination is a no-no. While there exists anecdotal evidence that high levels of nitrogen fertilization can lead to fruit aborts, the fact remains that pumpkins need adequate nitrogen throughout its entire growth cycle.

In fact, nitrogen has been cited by reputable university publications as the primary limiting nutrient in pumpkin production. Further, good science suggests that greater 1/3 of the nitrogen needs of field corn are required post-pollination. Fair to consider this an apples:oranges comparison, but the fact remains that regardless of the crop, nitrogen is an absolutely essential nutrient post fruit set.

How do you know if you have enough? Those of you who purchased my soil fertility guide surely have read my math and comments on nitrogen needs in giant pumpkins. In a nutshell, I believe that >5% organic matter can supply the nitrogen needs of a giant. Especially if you provided any supplemental nitro in the first third of the season.

For those with 5% or more OM, I'm not averse to weekly or bimonthly addition of low-dose nitrogen. I'll continue to apply Azos as well as fish/seaweed emulsion on a rotating every-other week basis.

Read your leaf color. Its probably the best indicator short of in season soil sampling we have for nitrogen status of the plant. Get familiar with the very identifiable yellowing that is indicative of nitro deficiency. just dont confuse it with pathogens or disease. Severe root rot/root pruning leads to inadequate nutrient uptake which can manifest as nutrient deficiency.

Nitrogen is a mobile nutrient within the plant. This means it can take it out of older leaves and reallocate it to the fruit and/or new growth. Thus, nitro deficiency will often show up in old growth first.

Happy growing.

7/22/2018 8:26:57 PM

Mill Bay, British Columbia

Thanks Joe. Great information, thanks for the refresher.

I refer back to your fertility guide frequently and would advice new growers to purchase a copy if there are any left available.

7/22/2018 10:18:01 PM

Wisconsin

Urea for the win guys

7/22/2018 11:17:51 PM

Anamosa, IA BPIowegian@aol.com

My personal best pumpkin was growing in the lowest, wettest spot in the patch in a wet spring 3 years ago. Leaves were a little on the yellow side, vine growth was slow. Once the pumpkin was beach ball size, about mid-July, I spread blood meal for slow nitrogen and 10-10-10 for faster N plus some P and k. My soil is silt over 80' of sand, so no worry about salt build-up from the 10-10-10. Salts leach right out. I let the rain and a little watering get the fertilizers into the soil. The plant greened up, vine growth took off, and I got steady fruit growth through August, but it slowed down a lot in September. No abort, no splits, no problem. I just made sure I didn't apply too much and it worked out great. I probably could have fed it some more in September, but it was such a good looking orange pumpkin that I didn't want to take a chance of blowing it up.

7/23/2018 12:15:36 AM

Grittyville, WA

I am confused maybe you guys can straighten me out... How would a magnesium deficiency compare in leaf coloration?
Or iron? These are used to green things up also.

7/23/2018 2:34:44 AM

Mill Bay, British Columbia

It doesn’t compare Glenomkins, a tissue test would be best to determine micro-nutrient deficiency otherwise to the average grower it’s just a guessing game.

7/23/2018 10:33:47 AM

Anamosa, IA BPIowegian@aol.com

Real wet conditions are a good indication that nitrogen leached out of the soil. Since I don't have a budget for tissue testing, I have to rely on pre-plant soil tests and observation of the plant and weather.

7/23/2018 12:01:24 PM

Colorado

Joe ive been giving low dose nitrogen every other day and have been monitoring my salt levels while doing so.My plants look great,leaves look normal,pumpkins doing well and no disease issues .Its early but so far so good.

7/23/2018 12:36:07 PM

central Nc

I'm no expert pumpkin grower, but I would not say identifying deficiencies is a guessing game. While I believe it is necessary to push weights higher, it's a little scary to see growers gradually rely solely on computers to tell them how to grow. As a community, I don't think we should be exclusive of those who don't have the means, time, or devotion to conduct extensive lab testing on a hobby plant. BE ONE WITH THE PUMPKIN. haha. Magnesium deficiencies in most plants will have interveinal (sp?) chlorosis as the chlorophyll breaks down. You'll more likely see it if you are overdoing the K and have sandy soil. Nitrogen is a more overall yellowing on older leaves and usually the rest of the plant will look a lighter shade of green than normal, maybe some spindly new growth. I've never had iron deficiency but I believe you will have dark veins with the rest of the leaf yellowing as well due to its role in photosynthesis. Also, it will start in younger leaves rather than old based on my knowledge that iron is immobile. It can be difficult to identify deficiencies, but not impossible if you know what you've added. It's an art.

7/23/2018 1:56:31 PM

Grittyville, WA

I appreciate the chance to learn I certainly need to... thanks all for posting. I have been one of the nitrogen-wary growers but I now think balanced nutrition all the way through is the way to go. So... to the really new growers out there if your leaf veins are dark green but the leaf is yellow overall you might have enough nitrogen but the ph or micronutrients may be the issue... ? Am i right or did I miss the mark??

7/23/2018 4:37:33 PM

Grittyville, WA

Balanced plus a lot of K... I mean at some point if you are growing a world record then you are really dumping on all the stuff the pumpkin needs probably at levels that would read as 'excess' on a tissue test? Not at that level myself yet but thanks for any further help/ insight.

7/23/2018 4:49:58 PM

Griffith, In

Glenomkins, it sounds like you are leading to try to get your nutrient level to excess,,,I am not the most educated about this , but I would like to share what I was told by another grower more knowledgeable than myself. I was under the assumption that high levels of nutrients were ok as long as they were balanced. I have a tendency to have very high phosphorous rates thinking I'd be ok with high rates as long as I could get the others high to balance with it, but my friend explained to me that beyond very high in levels of nutrients is toxic, and toxic is very bad.

7/24/2018 12:37:27 PM

Ontario, Canada.

Joe > Love the Nitrogen topic. High N levels can get a Fruit Sink to achieve fast jack rabbit growth rates and reach its near epigenetic potential. If they don't blow up first... Big believer Nitrates after pollination and Ammonium Nitrogen only by foliar after pollination. However, one caution high soil Ammonium AN is micro nutrient competing -cation the soil. So recommendation is to always ensure maximum nutrient availability by limiting AN after fruit set. However this type of regime is not as important as it used to be. This given the advent of amino acid ferts that are readily thought to transport & trans-locate Micro's. Nevertheless growers at times become true Morons. Pushing with AN is hazardous to your blossom end. Supplement AN ferts with high does of Gylcine micro mixtures to keep of together.

7/25/2018 7:02:26 AM