Saturday, January 9, 2010

Hanging Out In The Greenhouse

Most of us in the US are experiencing temperatures that are far below what we usually have this time of year.  Compared to the sub-zero and single-digits in the middle of the country, the teens and twenties here in Virginia seem pretty tame ... but I'm still cold and I'm whining about it.  When I'm in the house, I wear flannel-lined jeans, a turtleneck and a hoodie, down slippers, and I cover up with a quilt whenever I'm sitting somewhere.  It's a different world, though, when I'm in the greenhouse.

Even though the temperature are in the 20's outside, on a sunny day the greenhouse will easily reach the mid to high 60's or more by afternoon.  As winter progresses, I find I spend more and more time piddling with things out there, whether there's stuff that really needs to be done or not.  To tell the truth, I have automated as much of the greenhouse systems as I can ... so it's not like I have to be out there every day.

Misting the cuttings?  I have a Mist-a-Matic timer.  My water line is heat-taped and insulated, and it's been fine for two winters so far.

Heat?  I use an 18,000 BTU ventless propane heater on a thermostat.  This big propane tank lasts about 3 weeks, and the price of propane is a little bit lower than it was last year.

I have to keep a small crack in the door open to supply a bit of fresh air, because this heater has a sensor that will shut it off if the oxygen drops below a certain level.

Ventilation?  I have automatic electronic vent shutters and an exhaust fan ... not that things get warm enough in winter for them to come on, you understand.

My most pressing winter concern is aphids.  The cool, damp, sunny conditions in the greenhouse are perfect fuel for an explosion of aphids if I'm not vigilant.  Lately, with everything surrounding my father-in-law's illness, I have been a bit neglectful and the aphids have begun to get the upper hand.

I don't use insecticides of any type in my garden ... I don't need to.  There are plenty of predators that keep the bad bugs in check, as long as I don't do anything to mess with the balance of power.  The greenhouse, however, is a different situation entirely.  I cannot allow pests like aphids or spidermites to suck the life out of my cuttings, potentially destroying next year's crop.  I have to rely on judicious use of chemicals.

Insecticidal soaps are great for aphids ... but they're not labeled for use on cuttings.  Systemic insecticides are more efficient against sucking insects anyway.  Orthene is good ... just not so good for humans, so I don't use it.  After considering all the various options, I settled on Merit (imidacloprid).  It's labeled for greenhouse use and for use on roses, it doesn't harm my cuttings, and it does a good job wiping out aphids.  I apply it with a spray bottle to minimize extraneous airborne particles, outfitting myself with mask, gloves, goggles, etc.

I sprayed on Thursday afternoon.  Today, I'll go out and wash things down.  Aphids secrete honeydew, which is sticky and can foster growth of mold, so I have quite a bit of cleaning to do.  While I'm at it, I'll cull any dead cuttings (not too many, thank goodness), rearrange the rooted babies, and organize my tools and supplies ... if I get that far.

(written by Hartwood Roses. Hartwood Roses blog)


  1. Have you ever used the granular Merit that goes in the soil? I am thinking of using it this year as a preventative. Because my normal potted rose supplier raised their prices about 20%, I will be planting significantly more bareroot this year. We have always had to pot a few and the aphids are always an early spring problem.

  2. The only preventive I use is fungicide ... and I've never used granules. I always like to take the most targeted approach to solving a pest problem, and I get weird about putting things into my soil. That said, it's a whole different ballgame when one has to be concerned about a customer's reaction to the appearance of a crop for sale. Maybe someone in the Tidewater Rose Society has experience with this ... they're very nice, BTW.

    When I took the roses out of the greenhouse last April, they were covered in aphids. I figured I'd bring them all out and get them arranged on the benches, then I would break out the Merit and take care of the little buggers. To my surprise, sparrows swooped in and began feasting on the aphids ... problem solved. If I could only get them to eat Japanese Beetles.

  3. Thanks for the backstage peek...information very helpful.


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