From

Location

Message

Date Posted

Easthampton, MA

So, I'm already thinking about next year. :)

I was looking through some diaries, and it occurred to me that I don't see people putting lights over their pumpkin starts in the spring.

I have a 400 metal halide that I use to start seeds, boost house plants etc. It occurred to me that when I move the pumpkin outside next spring, I could bring the light with it. It would allow for 24 hrs of light, and it's quite warm. I would expect it to keep a small hoop house very toasty on those cold spring nights. It should make for a very strong start on the season.

Has anyone tried this? I'm stumped why I don't see it as standard practice?

8/8/2015 6:10:07 PM

East Jordan, MI

At least for us, the plant grows plenty fast enough in the spring, so no need for artificial outdoor lights, unless maybe if we were to target the OH state fair (1st week of Aug).

A 400W bulb in a hoop house (along with the ballast) would definitely increase the heat, but maybe too much -- only one way to find out.

However, my opinion is that they need a light dark cycle.

8/9/2015 7:13:21 AM

Muddy Waters

I used lights to start the plants out in 2014.My plants were bigger that year.I should have done it this year.I went with my gut feeling and didnt.My gut feeling was wrong.June was cloud maggeddon.Should of hung lights.I use 1000watt lights.If you can think of it its been done.Butt most growers are playing liars poker.Shhh! Keep it a secret!!But go tell a friend!! Never trust your gut feeling.lol

8/9/2015 7:25:11 AM

Muddy Waters

yes I agree Cecil they need dark also

8/9/2015 7:26:23 AM

Central NY

Lol.. That's my motto... Never trust my gut..

8/9/2015 8:49:03 AM

Easthampton, MA

Secret.. Sshh. ;)

As for dark cycles, most plants don't need it. The dark cycle for plant metabolism actually occurs during the day as well. (The name is misleading.) A non-succulent plant does fine in 24 hour light cycles and I grow all my plants under lights in that manner. That is how I started my seedlings.

The teacher in me needs to elaborate. *grin* (I used to teach middle school science.)


There are two exceptions to this:

Some plants require a short light cycle to trigger blooming. Examples of these are any plants that flower in the fall or winter. Christmas cacti are common household plant in this category. Mum's are also an example.

The other exception are cacti. Plants take in CO2 through openings in their leaves called stoma. For most plants, these stay open, but close during drought stress since it is how the plant loses water (transpires).

Cacti however are adapted to very dry conditions and keep them closed during the day, and only open them at night when it is cooler. Growing cacti under 24 hrs of light doesn't allow them to open and they can't take in CO2 as a result. Three days under 24hrs of light and they drop dead. (I've done it, and learned the hard way. *smile*)

Since pumpkins flower under long day cycles, it's no problem for them in either case.

8/10/2015 11:33:52 AM

Easthampton, MA

Here is a brief synopsis of the process of metabolism for plants:
(Taken from, and slightly abridged by me: http://www.biology-online.org/11/9_plant_metabolism.htm)

The light reactions

The light reactions involve light striking the chlorophyll molecules embedded in the chloroplasts. The subsequent reaction results in the conversion of some light energy to chemical energy. In the light reactions, water molecules are split apart into hydrogen and electrons and oxygen is released. In addition, ATP (energy molecules) are created and the hydrogen derived from the water molecules are involved in “loading” NADP (sort of a cousin to ATP) which carries the hydrogen as NADPH. NADPH is integral in providing the hydrogen used in the second series of major photosynthetic reactions: the carbon-fixing reactions.

The carbon-fixing reactions

The carbon-fixing reactions used to be called the dark reactions because light does not play a direct role in their functioning (it happens day and night). The reactions take place the chloroplast. These reactions only occur if the end products of the light reactions are available for use. The most common type of carbon-fixing reactions in plants is the process called the Calvin cycle. In the Calvin cycle, CO2 from the atmosphere is combined with carbon and sugar. The combined molecules are converted into glucose. The ATP and NADPH molecules from the light reactions provide the energy. Some of the sugars produced are further combined into more complex sugars, or are stored as starch within the plant.

I hope that was at least a little interesting. :)

8/10/2015 11:43:20 AM

Easthampton, MA

Just a tad more if you've gotten this far. :)

So, the chloroplasts are why plants are green -- they are little green cells in the leaves. The light reaction is why plants remove CO2 from the air -- why people are worried about cutting down trees and global warming. This is also why plants give off oxygen, which makes us happy to breathe. :)

The 'dark reactions' are why plants grow in size -- the sugars are used to make leaves, stems, etc. And it is how plants make great things to eat like sugary berries and starchy roots like potatoes.

It's all a pretty amazing and awesome process. Science still doesn't understand how to create artificial chloroplasts. If/when we can, we could make green solar panels, make food when you can't grow it, make green animals that wouldn't need food, etc.

Gotta love plants!

8/10/2015 11:52:42 AM

East Jordan, MI

ok, so explain why 75 to 80 percent of the actual pumpkin fruit growth happens at night?

8/10/2015 9:20:46 PM

The following video clip is a good capture of what goes on at night - during the day these plants store up tons of carbs within the cells through the photosynthesis process and at night a pressure difference occurs within these cells allowing an uptake of water. The water swells the cells and creates the fruit's enlargement. Seemed pretty cool to me.

http://plantsinmotion.bio.indiana.edu/plantmotion/movements/leafmovements/pumpkingrowth/pumpkin.html

8/11/2015 9:26:50 AM

N.c.

What has not been mentioned is the effect of temperature. Many plants have an optimal temperature for the 'light cycle' and an optimal temperature for the 'dark cycle'. The optimal temperature of the 'dark cycle' typically being less than the optimal temperature for the 'light cycle'. So if you are growing in a region where the daytime temperatures soar above the optimal 'dark cycle' temperature you would not expect much daytime growth. If, however, you live in a region where the daytime temperatures are much closer or at the optimal 'dark cycle' temperature you may note equal growth day and night.

8/11/2015 10:44:56 AM

N.c.

https://books.google.com/books?id=4nrtCAAAQBAJ&pg=PA18&lpg=PA18&dq=why+does+fruit+growth+occur+at+night&source=bl&ots=vKyIYywG-9&sig=tXw57x_PTohmnEw91X9Mp74rwzA&hl=en&sa=X&ved=0CCIQ6AEwAmoVChMIlr23tf-gxwIVgUc-Ch3PIgqB#v=onepage&q=why%20does%20fruit%20growth%20occur%20at%20night&f=false

8/11/2015 11:44:11 AM

San Diego

If the pumpkin is growing mostly at night instead of both night and day, will it still be gaining the same weight everyday, or is day time weight lost forever? Does all the energy that would have been used during the day get used at night?

If I measure my pumpkin in the morning and then measure it again before the sun goes down, there is no difference, but it puts on all of its weight overnight. It gets hot during the day...

8/11/2015 1:18:05 PM

N.c.

The 'dark cycle' production is limited certainly by the availability of the the 'light cycle' outputs. Somebody your plant's ability to produce a fruit equal to it's genetic potential is negatively impacted by a number of factors which are somewhat easy to control. Like the acidity of your soil or the percentage of organic matter in your soil or the amount of water you provide etc., etc.. Pick the low hanging fruit first. I can not directly answer your question but Beni Meier may have some answers.

P.S. I have read that in some plants the addition of far red light to red light at a 1 to 1 ratio enhances the effect of the red light.

8/12/2015 9:14:18 PM

Easthampton, MA

Wow Biddy, that video is awesome. :)

Cntryboy - Your point is a good one. I hadn't considered that. Hmm... My experience and understanding of the process is really focused on plant growth, rather than fruit growth. Getting the seedling to move along more quickly being the goal. I've never tried to raise fruit under artificial lighting.

Condo raises an interesting point about temperatures. I hadn't considered that the rates of each reaction might vary due to temperature, plant specifics, and/or some other factors. Knowing the basics of the process doesn't necessarily apply evenly to all plants. That makes sense. :)

Perhaps in this situation, the fruit needs water to fill new cells and expand existing ones. Since the day is a period of high temps and high transpiration rates, the growth is quite low. At night, more water can be diverted to the fruit and so the biggest gains in weight are made then?

Obviously it would be impractical to try to light the entire plant once the fruit is growing. ;) But if you had funds to set up stadium-level lighting...

8/13/2015 9:34:40 PM