On 17 Apr 2003, Daniel Hanna wrote:
In Mike wrote:
Planting garlic, onions or chives (alliums) with your roses will repel
aphids and spider mites. Some people claim it will also control
blackspot and powdery mildew, but I can't vouch for that.

I wouldn't vouch for the garlic, onions and chives either! Chives in
particular can attract black aphids.

Hi Daniel,

Your comment intrigued me, because my father plants a garlic bulb on either
side of every rose and he has no aphids or spider mites. I knew I had read
somewhere about studies being done on the effectiveness of alliums as
companion plantings, so I dug through my books and found this:

On page 61 of "Fool Proof Guide to Growing Roses," Field Roebuck states:
"Claims for the benefits of growing alliums with roses have been at least
partially tested and found to have some merit. For reasons largely
unexplained, the edible alliums - garlic, chives, garlic chives and onions
- have demonstrated varying degress of effectiveness against aphids and
spider mites. And, in at least one controlled experiment, when planted
underneath roses, garlic chives completely eliminated spider mites and
significantly reduced the aphid population."

He didn't mention what study/where, so I did a search on the web for
study/aphids/alliums/roses and found mention of two studies done by
Universities here in the US.

University of Rhode Island:

http://www.uri.edu/ce/factsheets/sheets/compplant.html

Cornell University:

http://www.cce.cornell.edu/suffolk/g...c/complant.htm

Unlike Mr. Roebuck, who stated it is unknown how alliums repel pests, both
these universities state that these companion plantings work by disguising
the smell of the roses. Both say pests locate your roses by smell and the
strong smells of these alliums prevent them from finding your treasures.
However, I don't know how that would rid an already infected rose of spider
mites, as Mr. Roebuck claims in his book. Your claim of aphids being
attracted to chives would also seem to suggest that it would only further
tempt the little stem-suckers and make the problem worse.

This requires more research than I'm willing to do at 11:00pm. I know Dad -
who lives one street behind me - doesn't have to spray for aphids or spider
mites. I just think those sloppy stalks on either side of all his rose
bushes are quite unattractive (ugly!) Ultra-Fine works great for me.
Jammer/Juls (btw: if you're reading this - which do you prefer?) asked if
there were companion plants that repelled pests and I was offering him
Dad's little trick.

I love the way this group forces me to do research!

Mike
z8TX