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Deer Park, WI

Just wanted to share my observations- I have concluded that there is a DIRECT correlation between night time temperatures and fruit growth. While this may seem a "no-brainer" for most, it does answer some potentially discouraging questions that new growers may have. Please read on...

Having been an AG grower for 4 years, growing in what i feel is good soil (as confirmed by soil analysis), using great genetics, and committed growing practices, I have come to expect daily circumference gains between 4-6" during the early stages of growth. Up until this year, i have been blessed with these types of growth rates on the majority of my fruit. But this year is different. Way different. I have improved my soil, growing practices, and genetic potential, yet I am continually disappointed in my daily growth measurments. Im averaging 0.5-3.5 inch gains. Frustrating!!

Why why why? We've had one of the coolest night time temp. summers on record. It regularly hits 80-85 degrees during the day, but it cools to 49-52 consistently at night. However, the last couple nights the temps only dipped to 60, and i've recorded my first set of gains in the 4-6" range. I know this is the direct result of temperature fluctuations, as there were no other factors influencing growth (fert, rain, etc.)

My conclusion is that night time temperatures truly govern fruit growth rates. Dipping below the 60 degree mark (at least for myself) significantly slows growth, whereas remaining above this temp. allows for maximal potential. Take home message: if you think you are doing everything right, but not seeing the gains you expect, check the thermometer during the night.

7/29/2004 9:42:07 AM

Indiana

Hey Dude,
I started recording that data about the last time I talked to you, and also a daily top 10 (for average), and its like clockwork daily gains line up in the same order as the temperatures.

Tom

7/29/2004 10:01:10 AM

Ontario, Canada.

Joze, Thank you. Will covering the fruit at night in blankets help any.

7/29/2004 10:03:04 AM

Vermont Green MTN State

Ha... Ha..
My pumpkin prefers fleece!

7/29/2004 10:06:53 AM

Walkerton Ont

I cover the pumpkins when it comes near the end of aug or the middle, depends on how cold. When covering your pumpkins with a blanket, there are thinks that you got to take into consideration, cause if not there could be a problem

7/29/2004 10:42:18 AM

canal winchester ohio

The last 5 nights it was in the mid 50's but thanks to 2 friends advice ( Tom & Alun) I kept them tucked in & despite the cooler than normal nights my squash still went from 29" to 57 " in 5 days...............Paul

7/29/2004 10:48:41 AM

[email protected]

Joe,

Here in the Metro NY area we haven't dipped below 61F at night in a week. But daily haves haven't been more than 71F for a TEMPERATURE DIFFERENTIAL of app. 10 degrees.

Growth slowed. Lack of sunshine certainly influenced this as well but............

Do you think growth might also be influenced by differential within a range?

7/29/2004 10:53:39 AM

Eveleth MN

seems to be the case here also, I usually average ~50-55*f at night and me best 1 day gains have been on nights above 60*f (which are rare in my area) day time temps don't seem to matter as much as long as its above 70*f

7/29/2004 10:55:23 AM

I'm with Gordon... GO UTES!

Wow, this is one of those things that, well, it was always
rumbling around in the back of my mind but never brought out
into the open to examine on merits.

I live in a high desert. We routinely have 30 to 40 degree
swings in temperature over the 24 hour period. It's not
uncommon to have 90 temps in the day and 50's at night.
It's not uncommon to see 40's at night during the summer.
And, despite all my work on the soil, I just don't see
(relatively) much growth in my fruit past the 20 day mark.

This could be the answer. Blankets at night. Hmmm.....

SHAZAMM! (quitely floating back into the ether..........)

7/29/2004 11:12:18 AM

Joliet, IL

i wish i would have blanketed the kins, and i thought about
it but never followed up. all kins lost over 1 inch per day
in circ. growth over that 4 day cold spell here. if the
cold temps come back again, i will blanket them every night
except when night time storms are predicted. and as the
season progresses and colder temps arrive due to seasonal
change, they will be on again. i would put them on every
night regardless, but is it safe to do so with the
possibilities of creating conditions favorable for rot
spores to take hold?

7/29/2004 11:35:36 AM

canal winchester ohio

To take this a step futher I'm hoping "knock on wood" that by keeping the squash a constant temp during the cold snap that today when it starts to warm up I'll avoid the splits that can occur when you get that sudden growth that always follows a warm up......I'll let you all know in a few days.....Paul

7/29/2004 11:36:54 AM

canal winchester ohio

shazzy, I'm changing the blankets daily & cleaning them to keep them clean & dry. It might be overkill but I ain't screwing around :)

7/29/2004 11:38:29 AM

Ohio

Im going to start covering mine up as well, thanks Joze

7/29/2004 12:10:48 PM

Hilpoltstein, Bavaria, Germany

I made exactly the same observations over the past few years...

This year it is very obvious again: For the past few days temps went down to 4°C to 7°C every night and fruit growth has almost stopped, just like the small growth rates that you describe.

I also found that covering the fruits with a blanket helps absolutely nothing. I guess one would have to cover and keep warm the whole plant...

Many of my fruits are around 25 days old and I can only hope that they don't get the impression of it being fall already.
If August should have some decent weather and the fruits pick up on growth speed again it could still turn out to be a good year but I really doubt that with all the bad weather we have had so far this year.

Good luck to everyone who is "blessed" with the cold weather!

Martin

7/29/2004 12:14:58 PM

canal winchester ohio

Martin,
I had a friend of my brother's that we got started growing giant pumpkins call him & tell him of his slow growth that started last Thursday & Friday ( he went from 4" a day to just over 2" ). We told him to blanket them & by the following day ( 36 hours later) he was up to 4 1/2 ".
It may have just happened that way, it may have been the blankets.....But he was very happy none the less.

7/29/2004 12:30:37 PM

Eugene, OR

Cliff, I also live in what's called the "high desert" of southern Oregon. My two best pumpkins at the moment have been averaging 4-5" circ gains per day with over a 40 degree temperature swing. Daily highs have been in the lower 90's with nightly temps dipping down to the lower 50's and upper 40's.

Being a dumb rookie as most of you would call me, I had no idea what I was doing but I was concerned with the nightly temps. I started using thick blankets draped over the pumpkins to keep them warm during the night. It just made sense to keep them warm and I'm happy to see that I'm not just imagining the difference in growth. They now grow more at night than they do in the day!

I've also started only watering around 10 AM which is just when it starts to warm up here. The water is so cold out of the tap that it really cools the soil down. My thinking was that the soil would have enough time to warm up thoroughly during the day and would retain some of the heat after dark and keep the plant pumping.

For those of you who think you have it bad, move here. We have had snow on the 4th of July, frost on August first, and the growing season is pretty much over by the first week in September without some sort of frost protection. I'm just hoping an August frost doesn't decide to end it early for me!

Good luck!

7/29/2004 12:39:13 PM

Wv

Warmer temps are here it looks like for a week or so.

7/29/2004 1:26:54 PM

In the shade - PDX, OR

I was thinking about conducting an experiment to enclose the fruit in a heated mini-green house. It would be opened during the day, but closed and heated during the night. If you heat your cloches during the seedling period what the heck is a few hundred more bucks with the meter spinning at night?

Just didn't have enough time to complete this experiment year.

Joe - this idea came from your off-season sink & source rants. I agree with you that higher overnight temperatures are directly related to larger circumference/weight gains.

Brian - good for you using blankets. These help protect the fruit as well as increase the insulation factor. I have had good results using these as well. You will also find the the majority of the fruit growth happens at night. (Has to do with the translocation of the photosynthate to the sinks.)
Did I get that right Joe?

Grow 'em BIG Ya'll!

7/29/2004 2:22:01 PM

Deer Park WA

CEIS, you are correct I have measured at night and then in the morning and found the largest weight gains occur at night. As for covering the fruit I cant tell you if it makes a difference because I have allways covered the fruit with blankies or lots of old towels and close up my pumpkin huts at night. Have been finally hitting 20# per day on several fruit for the past 4 days. July average day time high 91 degrees, average night time low 50 degrees.

7/29/2004 3:20:29 PM

Deer Park, WI

Going back to Tremor's question- yes i do believe Temperature flux influences growth as well. It is documented that optimal growth for pumpers is 85 degrees during the day, with a 20 drop to 65 at night. A temp swing of 20 degrees is not all that stressful, and pumpkins actually prefer the cooling off during the night for optimal respiration to occur.

Larger swings than this induce stress on the plant, and as we know pumpkins are very susceptible to stress.

Regarding your situation specifically, it is also documented that the rate of photosynthesis doubles with each 10 degree rise in temp, maxing out around 85-90 degrees. So it serves to reason that growth would slow on a cloudy, 70 degree day compared to a sunny, 85 degree day.

7/29/2004 3:35:00 PM

I'm with Gordon... GO UTES!

I've already resolved to try a warm wool blanket AND a tarp
over that.............

7/29/2004 3:40:49 PM

[email protected]

If nightly large weight gains continue to be the norm (as I have also noted), then tonight should be great. Our best fruit gained 4.75 inches today in the 8 hours between 9A-5P. I swear I could HEAR the fruit grow.

7/29/2004 6:00:16 PM

Eau Claire, WI

I bet the growth rate has more to do with the temperature of the leaves at night than the temperature of the fruit. Once the pumpkin has grown a little, there is so much thermal mass in the pumpkin itself that it wouldn't cool down much at night unless it was very cold. On the other hand, the thin leaves and vines would cool off quickly and slow down the metabolic rate of the entire plant. Blankets would be easy to do but I suspect the benefit is relatively small. Now if you could figure out a way to keep the entire plant at about 80 degrees every night...

7/29/2004 9:19:52 PM

Walkerton Ont

enclosure with propane cylinders running lol

7/29/2004 9:21:18 PM

Indiana

Ok who is gonna be the first person to put an electric blanket on their pumpkin and see if it makes a difference???
Steve

7/29/2004 9:35:05 PM

Key West, FL

nights are always cool (mid 50s) here, our pumpkins still grow.

7/29/2004 11:13:13 PM

Whidbey Island

OK, blankets are so 20th century. My son bought me a greenhouse hot/cold thermostat with 4 110 outlets. I set the fans on at 75 and the heaters on at 65 degrees. I bought old space heaters and fans at garage sales and aim them at the fruit under the tarps. A bit of plastic over the whole mess keeps them dry in the rain. They never get too hot in the sun and never get too cold at night. Just don't put the heater too close to the fruit or you'll have pumpkin puree. I used to put 60 - 75 watt bulbs on them, but that was just a bit too timid.
WPM

7/30/2004 12:15:00 AM

Hilpoltstein, Bavaria, Germany

Jim,
I absolutely agree with you.
Like I already mentioned covering the fruit with a blanket helped absolutely nothing for me.
I even tried an electric blanket (here go are, Moondog) without any positive effect on the fruit.
I would say that the plant just can't provide the fruit with enough "Juice" if it is too cold, like you said, Jim.
Martin

7/30/2004 3:36:13 AM

C N Y

yes, Jim R, i couldn't have said it better under any circumstances. i'm sure that the pumpkin itself being comforted will help it a little bit, but the plant itself is what drives the pumpkin, so..........WARM IT UP!
ahem---cough..03450847(*(*(*--eric

7/30/2004 6:57:31 PM

Circleville ,OH.

In 2001 I lost my main plant and pumpkin to bacterial wilt. I had stuck two secondarys( clones ) in an empty corner of my patch earlier in the year and after the loss of my main plant they took off and grew like crazy. well I had nothing to lose so I set all the pumpkins I could on the two plants the first week in September.

Now to what I was going to say.Im no expert but this is what I found that year. I coverd 4 of the best growers w/ shelters and blankets at night.2 had just shelter and no blanket. The other 5 were out in the open. I took daily measurments of all pumpkins and charted it on the computer.

I found that all the pumpkins responded to the temps all alike regardless if they were covered or not.The colder the night the less the growth across the board. Now some grew faster than the others but all eleven would grow and slow down proportional to there normal growth. We had an early freeze that year the first week of October and the pumpkins that were exposed got burnt and sofened from the freeze. The plant was dead by noon that day. Pumpkin Show was 2 wks away so I kept the 4 pumpkins covered and they still grew some even though the plant above ground was dead.

What does all this mean? I cant say , I still cover my pumpkins on cool nights.It does mean that even in a bad season you can still learn somthing by experimenting. By the way the pumpkin I took to the weigh-off was 280 that year, not bad for a cool months growth.......Darryl

7/30/2004 10:22:28 PM

Whidbey Island

Intuitively I would think that keeping the kin warm at night would mean less mass for the sun to heat by day. Darryl, your observations are very interesting and would suggest we should all invest 20 - 40 grand in huge greenhouses and keep the whole vines warm at night.......
WPM

7/31/2004 9:12:48 AM

Rexburg, Idaho

I'm not sure on this whole issue but I'm going to going to try covering the pumpkins at night.I have nothing to lose. My lows for the past week have averaged 47 degrees, which is pretty normal around here. Has any one measured the temp underneath the blankets to see if there is a real difference in temp? Because if there is no source of heat under the blanket I'll bet there isn't much tempurature difference. So to carry this arguement a little further has anyone tried an electric blanket to keep the pumpkin even warmer?

7/31/2004 9:31:57 AM

Indiana

see martins post above.

7/31/2004 11:23:15 AM

Hilpoltstein, Bavaria, Germany

The electric blanked helped exactly the same as any type of other blanket (I tried four different types): nothing!

I set the thermostat of the e. blanket to maintain 25 to 27°C and did monitor the temperature under the electric blanket with a digital thermometer which insured that the thermostat worked correctly.

I also had a thermometer under the normal, unheated blankets and found that the temperature will slowly fall as the pumpkin gives off its stored warmth. Just before sunrise the temp. under the blanket was only about 1 to 2°C higher than the outside temp.

So, I am pretty sure that just keeping the fruit warm helps nothing.

One would have to keep the entire plant warm, i.e. all leaves under a heated greenhouse, soil heating cables in the root zone and electric blanket over the fruit.
I don't want to see the electric bill...

Best wishes,
Martin

7/31/2004 1:04:02 PM

Okla

Let me see if I can get this right about what Joze, Tom and Paul and anyone else has tried to say. You cover the pumpkins or squash when there is a bigger difference from high temps during the day compared to low night time temps, say like going from 102 in the day to 70 at night. That is a 32 degree change in temps and it really STRESSES the fruits out causing daily gains to go way down or maybe even causing the fruit to stop growing or even worse SPLIT wide open. What you are trying to gain by "Tucking" the fruit in at night is not so much to keep it WARM but for it not to go thru a big temp change, to try to stop the fruit itself from experiencing the (stress) big temp difference from the high to low temps, therefore you do not have the fruit kick into a slower daily gain. Yes the plant has a big effect on how the fruits grow, but the fruit itself can be effected also by different elements, Why do you use calcium on the pumpkin itself, why not just spray it on the plant? Because it effects how the fruit itself is more solid maybe. I try to listen to these growers who have been growing a lot longer time than I have but it was to late before I took the right action and guess what, the fruit split wide open because of the big temp difference from high to low. Growing is not doing just one thing to a plant or pumpkin. To get a huge fruit you have to do a lot of things, big and small, to the plant and "the fruit" to get the best results!
I say Thank You to the Growers who have been growing for a while for still coming on here and giving what TIPS you can to help get bigger fruits. Just wished more of them would come back in here and do it, like they used to do. I miss the older growers coming in and helping where they can.
I also want to say Thanks to the newer growers who have a lot to contribute.
Now if I am wrong about what I have posted, please, correct me.
Thomas

7/31/2004 3:50:01 PM

Indiana

Its amazing what a couple warm days and nights are doing! I had a over 40# gain today on the Ford Im gonna go measure it again just to be sure. Last week the fruit slowed so much i thought they might stop completely, must have been the cold!

8/1/2004 3:06:59 PM