Grow Parthenocarpic Cucumbers for a Disease-Free Harvest

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Posted by @critterologist on
Parthenocarpic is a technical term for "no pollinator needed." Parthenocarpic cucumbers can be grown in a greenhouse or even indoors. To protect them from pests and diseases, they also can be grown outside under a tulle row cover.

Parthenocarpy means fruit formation without seed formation. We're used to eating parthenocarpic bananas, which would otherwise have hard black seeds, and other fruits have seedless forms as well. Parthenocarpic cucumbers by definition are hybrids, since there are no seeds to save. Female cucumber flowers can be distinguished by the tiny cucumber shape at the base of the bloom. In regular varieties, pollination is required to fertilize these little ovaries and let them develop into a harvest of cucumbers. With parthenocarpic varieties, all the flowers are female and develop without need for a pollinator. That's good news for home gardeners struggling with cucumber blights and diseases, most of which are spread by insects!

Where do you find these specialty seeds? US seed companies seem to carry limited parthenocarpic hybrids, with most being slicing types. I found 'Beit Alpha' and 'Quick Snack' at Victory Seeds. Johnny's (https://www.johnnyseeds.com/se... ) carries a decent variety, of which I've tried (and liked) 'Excelsior', 'Katrina', 'H-19 Little Leaf' (pickling/snacking) and 'Unagi' (a Beit Alpha x long Asian cross). Nikitovka Seeds, in Ukraine, carries an extensive parthenocarpic selection of both picklers and slicers. https://nikitovka.com/us/en/

Last summer I wrote about using tulle netting to keep insects and other pests out of garden crops, including parthenocarpic (no pollinator needed) cucumbers. https://garden.org/ideas/view/... I covered my cucumber trellis by winding 2 layers of tulle around it, top and bottom. That worked pretty well, but the vines had a tendency to grab the tulle with their tendrils, and in the process of continually separating the cover from the plants to harvest, I created a few holes, and eventually insects (and disease) got through.

This year, I created PVC arches to hold the tulle cover away from the sides and top of the trellis panels. For this project, you'll need a cucumber trellis, tulle, stakes, and PVC "pex" pipe. The dimensions and amounts will vary according to your garden. You could forgo the trellis and create a low, wide "hoop house" over your row of cucumber vines. Hopefully, describing my project will let you adapt the idea for your garden.

I should mention that my cucumber trellis consists of four flat trellis panels from Aldi, laid out in a shallow zig zag so the wind doesn't catch them as easily. There are 3 metal supports pounded about 10 inches into the ground where the panels meet, and zip-ties connect the panels to the supports.fi

After fiddling around with 57" wide tulle last year, I obtained a bolt of 10' wide tulle on sale in January. I found PVC "pex" pipe at Lowe's. The 3/4" size (outside diameter) slips nicely over those green plastic coated metal stakes. Rebar would also work, just be sure your stakes fit inside the PVC (for 3/4" pex pipe, you'd want 3/8" rebar, not half-inch).

Learn from my mistake, and do not get the coiled 100 ft. roll of pex pipe, even though it fits so much better into your car! I was told put it into the sun, and it could be easily straightened by counter-bending. I spent an hour wrestling with a piece of it, trying to hold it in place against a tree trunk while using the weight of my body to straighten it. Bounce, bounce, slide it 3 inches, bounce, bounce... I got it straighter than it was, but not straight enough to make an arch that stayed upright. Happily, Lowe's let me return the roll and exchange it for 20ft lengths.

For the height of my trellis (about 5 feet), I calculated a 15 foot length of pipe would make an arch 3 feet wide at the base with plenty of clearance at the top. My lengths of PVC weren't quite straight, but a little bit of easy counter-bending (no tree trunk required) took care of that. I found the 3/4" pex cut readily with my loppers.

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I used 6ft stakes along the main part of the trellis, spaced 2-3 feet apart. At the ends, I used 4ft stakes (since that's what I had on hand), placed them 20" from either end to get enough clearance over the end panels. Since we'd just had a good soaking rain, I was able to pound the stakes nearly a foot into the ground. Tulle is lightweight, so you don't need super sturdy supports for it. My 3 middle arches each used 15' of pex pipe, cut from 20' lengths from Lowe's. Two of the leftover 5' pieces worked fine on the shorter ends, with the pipe just going over the tops of the stakes and not all the way to the ground.

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I then measured my hoops end to end and added enough length to reach the ground on both ends. For me, two 25' lengths of 10' wide tulle was more than adequate. I put the tulle over the trellis hoops, overlapping a few feet over the top and leaving a few inches on all sides so it can be pinned to the ground with landscape staples. I used a pair of snap clamps to hold the tulle to each arch, high enough that they'd also catch the overlap from the other side. From my experience with it last year. If you use 54" tulle, I'd suggest actually sewing or at least basting the lengths together to create a piece wide enough to cover your arches.

Snap clamps are measured according to the inside diameter of the pipe, but pex pipe is generally sold according to the outside diameter. So, subtract 1/4" from the outside diameter of the pipe, and that's the size clamp you need. I bought my 1/2" snap clamps from Greenhouse Megastore, a source I also recommend for "mega heavy duty" 1020 trays and other goodies. There are other ways of securing fabric to PVC, but snap clamps seemed easiest to me.
If possible, get somebody to help you put the tulle into place. I tore a hole in one side wrestling with a snap clamp but covered the hole with an extra piece o tulle.

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