I used a Gardener Supply SWC last year to grow an Atlantic Giant pumpkin. The vine got to 20' when I pruned it to limit further growth. The pumpkin was about 24" in diameter when a killing frost hit a month earlier than usual (first week of Sept instead of 1st week of Oct). It was just a 'baby' ;-)

I went open topped and fertilized without the strip.

The container held 2 cu ft of mix and had a water reservoir of 4 gallons. I filled daily when it was hot and the vine large, every 2-3 days early on. This was enough.

I am confident a large watermelon can be done and in fact will be doing watermelon this year, although not the freakishly large type ;-)

If the variety you will be growing is meant to grow to abnormally large proportions then I would suggest fertilizing full strength with every watering to full strength every week. I ferted with full strength MG and full strength NH Fish liquid once per weak and felt that while this was OK, the plant could take even more without any chance over overdoing it. You kind of have to pick a routine and monitor your plants and make some guesses along the way.

It might be simpler to use a cover and fert strip, you have to consider the grower here. You know your daughter, I don't.

Fun experiment though! I am doing something similar with my son who is growing a freakishly large cabbage this year.

Good times.

Thanks JAG, just what I wanted to know. Did you mix CRF with your potting mix as well? I do have the NH you suggested as well. Did you use the same MG the entire time or switch to a lesser nitrogen formula. I had just got in my order from dyna bloom saturday. My daughter is married and both of them I think are having a side competition with his brother so I am sure they will put whatever effort is needed :)

I am trying to recall if I used CRF or not. You would think that by now I would realize how bad my memory is and take better notes ;-)

I am not sure, but will guess that I did.

The MG would have been 15-30-15 and wasn't MG, but Sam's Club brand (wouldn't be surprised if it's the exact same thing). I doubt it was the best choice. In general I have been moving away from the high P ferts as I just don't think they do many plants any good and can cause problems.

I am definitely not trying to say I have the 'ideal' fertilizer program figured out for these monster plants. I can only tell you what I did and what the results were. I am still most definitely in the experimental phase when it comes to growing the huge fruiting plants.

For the cabbage my son is growing with me I used CRF in a 1-1-1 ratio and plan on using DynaGro Foliage Pro. I was going to use it exclusively, but best I can tell from researching is that cabbage uses as much calcium as it does nitrogen. I will need to supplement this.

In the case of your watermelon I did a brief check at a single source and it appears you may be best with a 6-1-6 ratio. I haven't double checked this anywhere so don't take my word for it. The 3-1-2 ratio is probably close enough. The moral is a high P fert may not be the best choice. Really wouldn't surprise me at all if a fert a little on the high N side worked out great for the entire season.

But, like I said, I am in the guessing zone here. I don't have it all figured out.

Here is another source on nutrient uptake for watermelons.

From this it appears that nutrients removed from the growing soil by the melons was in a ratio of 5-1.6-10.

Tissue analysis showed a ratio of 3.6-.48-2.7 in the plant.

Calcium also appears to be needed in high amounts. Almost double the Ca was removed from the growing soil as N. I would suggest using lime or gypsum as a supplement.

I still think if you are going to rely primarily on a single fert source you would do well with the Foliage Pro all season. The 3-1-2 ratio appears a better match than the bloom formula which is P heavy.

If Al happens to read this (or anyone else) I would be interested in what others think of the value in high P fertilizers. Personally I don't see the value in them since it appears virtually nothing needs P is such a high amount.

I would like to see pics of your cabbage later this year. My original plan before I left a message on here was to do either the foliage pro or MG until the first fruit. Then I was going to switch to maybe dynabloom with the earthjuice bloom as a supplement (not sure its needed now however). Somehow when I ordered from dyna I got the foliage pro, the dyna grow, and the dynabloom. I think I hadn't realized I ordered all 3 as I thought I was just getting the foliage pro and dynabloom. Anyhow, not sure when or if when I should dynagrow as opposed to foliage pro. Just when Al talked about cutting down on all the different types of fertilizer I end up with more than ever, lol.

I have garden lime that I was going to use when I mixed up the soil. I do have gypsum and epsom salt if more of either one is needed.

I value your opinion so thanks for giving it to me. Sounds like you did well on your pumpkin and just ran out of time. I think I have considerable more time here in Texas as it can grow until October when we get our first freeze (or end of Sept when fair starts).

I have used the dynagrow formula (7-9-5) for a couple years on houseplants in hydroculture as well as for 'general purpose' reasons on a variety of plants. I always regarded it as a product worth using, but my opinion on high P ferts has changed.

I would love to hear other's thoughts on this.

In any event I can tell you that any of the ferts you purchased from dynagro or the NH stuff will give you good results. You really don't need to worry about the ratio too much unless you are trying to push the envelope as far as you can. I have a disease that requires me to push things and never allows me to be satisfied with last year's results ;-)

If you are trying to grow a giant sized veggie, then pretty much by definition you are pushing the envelope as far as you can ;-)

Perhaps in the fall/winter we can compare notes. For now, this is my SW container grown pumpkin whose vine was killed a month before maturity. Hopefully this year the first frost waits awhile and I can do even better.

In the foreground are 2 of the largest 'Jack O' Lantern type pumpkins I could find. I did not grow them myself.

{{gwi:19157}}

Geeez, thats a nice pumpkin. How much did it end up weighing? My daughter and her husband had a pumpkin growing contest last year but theirs died, lol. I'm not really trying to push it although they probably will :). I am really enjoying all the learning I am getting though. I'm soooo ready to play in my garden with all this new stuff I'm learning but will have to wait one more week. I'm a CPA so too busy doing tax stuff to play yet. I do get to play on this forum while I'm printing though ;). I will post how all my different things do so everyone can help me improve next year.

I don't know how much it weighed as I couldn't lift it (too large to get my arms around). I just rolled it into the front yard for a Halloween display. I will guess around 75lbs which is not that great for an Atlantic Giant. The seeds had the genetic potential to get 800+lbs. I have a lot more room for improvement, but did accomplish my goal of having Trick or Treaters wonder where such a large pumpkin came from ;-)

Definitely don't forget about us and do post how things did for you later on. All too often folks come to the forums, ask for a pointer to two and then disappear. It's really nice to see them stick around or at least come back and give some feedback on how things went.