Cold Frame Garden

Cold Frames, Aphids, & Air Circulation

Air circulation is critical for the success of your flower and vegetable garden and it’s just as important – if not more so —  for your crops in cold frames.

Why It’s Important

This principle of air circulation is important because it can reduce, destroy and prevent insect infestation and bacterial infection.

Cold Frames – What I do

My  cold frames are nothing fancy.  Bill put together some old folding windows someone had discarded years ago.  The glass eventually fell out, but we covered the openings with plastic.  I’m still using those same old frames after all these years.

If the temperatures go way below normal and high winds are called for I have to pile straw around the edges to keep the severe cold from seeping in around the bottom and freezing my lettuce.  When temperatures are normal, I like to have that air seeping in.  Keeps my plants healthier.

My cold frames in the garden.

When we have unusually cold weather and I have to leave the cold frames on for an extended period of time, I  get out there the first sunny day above freezing and take the frames off for the day.

If the weather man calls for a few days in the 40s and nights not below 30 I’ll just leave them off for that period of time. Like humans and animals, plants need  fresh air as well.

Your Cold Frames

Yours might open from the top and be a bit more stable or permanent than my old frames.  Nonetheless, I would urge you to open them up and let that fresh air and sunshine in often.

Here comes Spring and Aphids

As Spring arrives you have a greater chance of having aphids on your greens if they remain closed up in a cold frame.

Only One Bad Experience with Aphids

Many years ago I used straw bales for my cold frames.  Four bales together made a rectangle around the planted lettuce and an old window was placed over the top.  As it turns out it was a better place to breed aphids than it was to raise lettuce, even though I removed the window on every nice day.

I guess the bales kept enough air out to make for poor circulation. I killed a million aphids, but they still thrived.

Just so you’ll know, I’d better mention that this was the only time in 33 years that aphids got out of hand in my gardens. And it is the only time in 33 years that I have ever had aphids on my lettuce.

Kept Under Control

I have them from time to time, like almost every gardener has.  But if they are out in the open with all that air circulating they are relatively easy to keep under control.

In addition to good air circulation, my garden is home to several beneficial insects that eat aphids. (I encourage them by providing habitat.  Another post topic.)

Also I pay attention.  When I see them starting on the new growth (which they love) of roses, mums, or phlox I just put my garden gloves on and smush them.

The aphids on my roses are green, but the ones on the mums always seem smaller and are black. (They come in lots of colors.) They’re  always on the new growth at the top, so it’s especially easy with the mums to just pinch that piece off, smush and discard.

That’s usually the end of the matter, but I keep a check just to make sure.

Bottom Line

An ounce of prevention is worth a pound of cure.  AND — it takes less time to deal with.  Work with nature and keep that fresh air circulating.


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  • Thanks. More good advice. I finally have a little time to look back at the archives. I love the way you have it set up. I am trying to look at one month each time I have a few minutes. It’s good to go back and review even if I have read it before.
    Great job.

  • Hi Beppy,
    I’m glad you’re going back through the archives. Over the years I have found that to keep reviewing is one of the best ways to learn.

    The more we know, the more we have to build on, so when I go back and read something ——-lo and behold ——it has something new to offer.

    Sure glad you are enjoying the way I set it up. I guess as time goes on I will have to add more breakdowns. Suggestions are welcomed.

    Thanks as always for your encouragement.


  • I have aphids on my eggplant, which is planted in the middle of a 4-1/2 foot wide bed so it’s hard to reach to squish bugs. Is there an organic spray that works for these? Thanks.

  • A spray of water will get rid of the aphids, Heather. You might have to do it every day of so because ants will bring in the next generation of aphids.
    Update me in a few days if you have time.

    A suggestion — try planting your large plants like eggplant closer to the edge so you can tend the plant.


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