It has been a year

[Danny Stanford]

I have been running an aquaponic unit for close to a year now. I have grown corn, cucumbers, and melon plants, and get tons of flowers but never any fruit

[Vlad Jovanovic]

Most melons and cucumbers have both male flowers and separate female flowers on the same plant and need someone or something (honey bee, you...whatever) to transfer the pollen to he female flower. Without this, you'll never get any fruit. Corn...well IDK I'm told a 6' x 6' square patch of them is a good minimum for pollination to occur (by way of wind). I've not grown much corn though, so there may be some tricks you could use...maybe someone will chime in with some...

[Kyle]

Is your system in the open of in a greenhouse? It sounds like they aren't getting pollinated like Vlad suggested. If was only one species of plant I would give other suggestions but the fact all of them failed to produce  points toward pollination problems.

Also, where are you getting your plants from? Have you been using quality seeds/seedlings?

[Roger]

Danny - I believe the crew here is right.  You should try hand pollinating them yourself.  A lot of people will use a paintbrush. All you have to do is manually push the paintbrush into each flower until you've done that to all flowers.  I've also found that introducing oscillating fans helps move the pollen from one flower to the other as well.  Give either of these two option a try and if you don't have any luck then you'll know it is a problem somewhere else.  I wish you good luck! 

[Alex Veidel]

I concur with everyone else. That would be my diagnostic as well.

[Matt T.]

I heard that bees pollinate plants more by the flapping of their wings, than by direct contact, and that using an electric toothbrush really makes the pollen airborn quite well.

[Vlad Jovanovic]

Matt T...not all plants, nor their flowers are the same. The electric toothbrush may work fine on say, peppers and tomatoes whose flowers have both male and female parts contained within the same single flower...(heck, shaking them or tapping the main stem with your fingers, or the slightest breeze/movement is usually enough...often neither you nor the wind need even need to do anything...their practically 'self pollinating'...almost, but not quite, like beans and peas which are truly cleistogamic).

But with cucumbers and melons (nor most cucurbits), that is just not going to work real well since the female flower is separate and distinct from the male flower, so their has to be some mechanism of transfer...insects, or you...otherwise, no fruit. 

[Matt T.]

I agree Vlad. In fact a lot of the cucumbersand melons are open pollinating, that they have male and female plants as individuals. I am implying that by moving from flower to flower with the brush, you would in turn be pollonating by direct contact. Would a person be best off to grow plants intended for greenhouse production in cases like Danny's? I am curious about this myself. Also, can you tell the diffrence between the male, and female flowers at a glance, or do you have to check for stamens and pistols. Its been a while since I studied those flower parts in biology class, so I'm not sure if I got the flower parts named correctly.

Vlad Jovanovic said:

Matt T...not all plants, nor their flowers are the same. The electric toothbrush may work fine on say, peppers and tomatoes whose flowers have both male and female parts contained within the same single flower...(heck, shaking them or tapping the main stem with your fingers, or the slightest breeze/movement is usually enough...often neither you nor the wind need even need to do anything...their practically 'self pollinating'...almost, but not quite, like beans and peas which are truly cleistogamic).

But with cucumbers and melons (nor most cucurbits), that is just not going to work real well since the female flower is separate and distinct from the male flower, so their has to be some mechanism of transfer...insects, or you...otherwise, no fruit. 

[Vlad Jovanovic]

I've never seen a cucurbit that has "male and female plants as individuals", separate male and female flowers on the same plant... sure, but not as separate individual all male or female plants.

Yeah, cucurbits (cumbersandmelons) pretty much depend on pollen transfer by direct contact. In a greenhouse setting with a great number of plants, that task can become pretty tedious with a paint brush, so folks around here use bumble-bees. You can rent a hive for money, they deliver, set up, then pick them up as needed. Pretty cool.

Yeah, you can tell at a glance. The female flowers have an ovary (just under the flower) that pretty much looks like a little miniature fruit, the males do not.

[Sylvia Bernstein]

You can actually get self-pollinating varieties of cucumbers, mainly the English types.  This is primarily what I grow in my greenhouse 'cause the whole male / female flower thing is just too fussy for me.  Here is an example http://www.reneesgarden.com/seeds/seeds-hm/vegCh.htm....just look for the "self pollinating" varieties.

[Vlad Jovanovic]

Yeah, the first time I saw those parthenocarpic types was here in Europe. Seem great for greenhouse growers. I think that's what they were bred for, most are monoecious though types though...

Hehe, 'self pollinating' is a bit of a misnomer, since the 'self pollinating  cukes here (parthenocarpic ones at least) require no pollination to occur whatsoever. Pollination is actually detrimental, at least cosmetically and economically, since it often results in misshapen fruit!

Sylvia, I could not get that link you posted to open..."404 Not Found". I think you accidentally added the first word of your next sentence to the link, which might be why it's not working

[Roger]

I've grown the "Chelsea Style" from Renee's Garden and they are very heavy producers.  No pollination needed.  Great taste!

Sylvia Bernstein said:

You can actually get self-pollinating varieties of cucumbers, mainly the English types.  This is primarily what I grow in my greenhouse 'cause the whole male / female flower thing is just too fussy for me.  Here is an example http://www.reneesgarden.com/seeds/seeds-hm/vegCh.htm....just look for the "self pollinating" varieties.

[Matt T.]

   They actually do sell cucumbers that are all female flowers (gynoecious), and add in 10% pollenator seeds. The females produce more fruit, so there is less wasted space for production. I am not sure if this would be concidered a female plant, or is this due to hybridization? Interesting stuff non the less. Here is a link. http://www.johnnyseeds.com/p-6037-general-lee-f1.aspx

Vlad Jovanovic said:

I've never seen a cucurbit that has "male and female plants as individuals", separate male and female flowers on the same plant... sure, but not as separate individual all male or female plants.

Yeah, cucurbits (cumbersandmelons) pretty much depend on pollen transfer by direct contact. In a greenhouse setting with a great number of plants, that task can become pretty tedious with a paint brush, so folks around here use bumble-bees. You can rent a hive for money, they deliver, set up, then pick them up as needed. Pretty cool.

Yeah, you can tell at a glance. The female flowers have an ovary (just under the flower) that pretty much looks like a little miniature fruit, the males do not.