Donna-
this is old news. New SCIENTIFIC evidence simply does not support this information.
Many Hummingbird plants, such as Trumpet Creeper have at least a 33% ratio. This is simply wrong information!
Last season I posted a link to a scientific study that gave the ratio for many Hummingbird plants and I also printed a letter from author Sherri Williamson that I received from her answering my question about formula--I am pasting it below.

""Hi everyone- I am new to this forum but I have had the exact same question about sugar formulas.
I am sure many of you are familiar with Sheri Williamson who wrote "Attracting and feeding hummingbirds" a few years ago.
I went to her website and I asked her that very question via email. Following I will quote her answer and a link to a site with research that has been done on nectar content of flowers. You may all be surprised to know that most hummingbird favored flowers contain more nectar than any of us thought.
Quote from Sheri
"Some hummingbird experts do (or did) insist on a feeder solution no stronger than 4:1, but I've never been a member of that camp. On page 40 of Attracting and Feeding you'll find that I recommend a solution of three to five parts water to one part sugar - a pretty wide range. Hummingbird-pollinated flowers produce nectar that ranges in sugar content from as weak as 10:1 to as strong as 1:1.
Both of the extremes are rare, and the average sugar content is close to 3:1.
Studies of the birds' physiology suggest that solutions stronger than 3:1 may not provide sufficient water in extremely hot, dry conditions and that solutions
weaker than 4:1 may not provide enough sugar for the birds to maintain their body weight when the weather is cold (stronger solutions also freeze at lower temperatures, which is very useful for people lucky enough to host hummingbirds year round). A 5:1 solution can be useful in discouraging bees or helping the
birds through extreme heat and drought.
When I wrote Attracting and Feeding eight years ago, I was deliberately
conservative in my recommendations to avoid upsetting a handful of my colleagues
in the hummingbird community who were adamantly opposed to solutions stronger
than 4:1. Since then most of them have changed their minds, thanks in large part
to the article that begins on page 7 of this issue of the Louisiana
Ornithological Society News:
http://losbird.org/news/0326_201_news.pdf
I now feed 3:1 most of the year, except during the very hot, dry days of late
spring and early summer, and I do think it helps the southbound migrants and
overwintering birds. Using a slightly stronger solution may not be as important
to your feeding strategy with all the good natural food you're providing, but it
isn't going to do the birds any harm."
End of quote from Sheri )""

Donna those of us who feed a stronger formula simply are not hurting our beloved birds.
I ask you to please go to the site of the scientific study listed in Sherri's letter and read it for yourself.
The information you quoted does not even have any evidence or facts or science behind it. Where does the lady quoted get her information?
3 to 1 is not harmful and the experts are now using it!

Will you pleases read the information I have listed and then tell us what you think?

Thanks, Vicki

Hi Vicki...thanks for your input. The info I found was not meant to encourage anyone to change their ratio and you're right in that it certainly didn't include any scientific support. Admittedly, I'm not well versed concerning sugar concentration found in flowers. I have lantana and red salvia in pots on my patio but that's pretty much it! We have a backyard relandscaping plan for the fall, so I'd really like to add some hummer friendly plants.

What really got a little of my attention was regarding the 5:1 ratio in temps higher than 90. Well, here in the deep south, our summers are brutally hot and I just wondered if anyone else was using this ratio under those conditions. My first few hummers usually appear in mid March and are gone by mid Oct., so they are never exposed to any cold/freezing temps.

Thanks, too for directing me to Sheri's site and I will read that asap. Again, I just passed along the info only because I thought it was interesting. I am no expert and have always used the 4:1, however, you certainly have made some good points.

BTW, I'm delighted to report that my hummer population has increased somewhat over the past few days...YEA!!!!

Donna