The best organic means of control is just what you are doing, knocking them off with a strong stream of water. The next step would be an insecticidal soap spray, 1 teaspoon of a real soap (Ivory, Fels Naptha, any of the castile soaps, but not a detergent) in 1 quart of water (the amount can be adjust as needed for larger quantities as long as the proportions are the same) and then sprayed directly on the target insect.
If you have that much of a problem with aphids there is a problem with your plants that is attracting the aphids tht needs to be corrected.

Use of excessive amounts of nitrogen fertilizer attracts aphids like a magnet. The soap spray kimmsr mentioned works well and you'll find many other suggestions for aphid controls on the pest relevant forums - Organic gardening, Garden Clinic, Pests & Diseases.

Dave

Aphids love the fresh new flush of tender growth . Lady beetles eggs look a lot like aphids and are easily damaged by oil sprays or even soaps . Your best enviro friendly practice is to continue with a water spray but really blast the water as hard as you can at the aphids and try to get all sides of the leaves and flowers . Hand squishing is also an excellent choice . You're doing good !

I spray them with water until the lady bugs arrive and then sit back and watch the fun. Those baby lady bugs are so cute and hungry.

Someone elsewhere said that soaps coated exoskeleton of the aphids and killed them while washing them off with detergents or just water did not.

Have you ever heard this?

Aphids live for about 30 days, so if you knock them off your plant with a stream of water they will most likely die of starvation before they find their way back. Aphids do not move like lightening as some seem to think. If after knocking some aphids off your plant you see more aphids you have the next generation, or three, since aphids start to produce young almost as soon as they are born. Insecticidal soaps do have the property to disolve the exoskeleton of the insects that soap is sprayed on and that will dessicate the insect causing it to die, but is the IS better than just a spray iof water? Probably not since you could just as easily spray a beneficial insect with it causing that insects death.

Thanks for the answers. I'll get some Ivory soap today. I had to go out of town for the weekend. I came back to aphids on the zinnias again. They're not bothering the nasturtium much this year, only a few salvia and select zinnias. The same zinnias a foot away are left alone.

If I use Ivory, is it OK to use that in sun? No need for sun protection with that like with insecticidal soap, is there?

Thanks, everyone.

Karen

I don't really go after the aphids but I don't practice food gardening and I don't grow roses or other any extremely high maintenance flowers(but I do have multiflora roses that I wish the aphids would eat). They don't seem to significantly bother what I have or I am too clueless to notice. Rabbits and deer are another story.

Other than water nothing should be sprayed on plants if the spray is going to be on the plant in temperatures over the mid 70's. Spraying early in the morning or late evening is good, but not mid day.
Bob, why do you think roses are "high maintenance". Only if they are grown in bad soils or under the wrong conditions would they be any harder than any other plant.

Thanks, Kimmsr. I've been using the Ivory on them. I somehow broke my pressure sprayer and have had to use a little spray bottle (like a Windex bottle). Hope to get to Home Cheapo today for a new pressure sprayer.

I think roses are a pain too. I used to have 45 of them but got rid of all. To have pretty ones required pesticides, fungicides, and constant vigilance. In the early years I kept them well maintained but even with yearly compost additions, the soil seemed - ?spent?. They probably needed transplanted into new well amended soil. I have heard that some of the newer cultivars like Knockouts are more resistant but I've not tried them. My wintersowing has overfilled my yard and all planting beds.

I can't seem to get over my zinnia addiction, though.

Karen

What about boosting the ladybug population and buying a package of them for your garden? Keep them in the fridge until near dusk, spray your plants with water, then scatter them around the garden where the aphids are.

Sue

If there are ladybirds (ladybugs) moving in that is a good sign. Don't forget that although they DO eat the aphids it is their larvae which really vacuum them up. So you need to give the adults time to mate and lay their eggs before you see a real difference.

Rugosa roses are the way to go. Beautiful leaves and flowers, repeat blooms with lovely fragrance, pest and disease free, hardy. They tend to spread, though.

Sue: Are you going to tell me that you have bought ladybugs, and they STAYED in your yard? Don't they just fly away?

flora: Ladybug larvae "vacuum them up"? If the ladybug eats the aphid, what's left to vacuum? I don't understand.

I'll tell you, the wealth of information on this forum never ceases to amaze me.

Karen

Kimmsr, you might have busted me. Since I don't grow roses I guess I can't say from experience that they are high maintenance. I had read or heard in a few places that at least some types are a bit of a pain and that aphids can be a big pest for roses. Maybe there are some types that had some of the better traits bred out of them and that was what I was thinking about? Also, since I have limited time and am trying to restore a large area I really need plants that don't need much help from me. I generally go for hardy natives suited to their spot that don't need amended soil, winter protection, etc.

My favorite 'cure' for aphids is to grow nasturtiums in several of my gardens. Supposedly aphids prefer those over your vegies. Also, we have a lot of ladybugs, I mostly see them in the house, but of course they are coming in from outside. I took some to the U.W. Extension once for ID, I thought they were some similar looking thing and wanted to know how to kill them safely. Felt guilty when I found out they were real ladybugs. Should have packaged them up and sold them! They were coming in cracks in the foundation and the bathroom fan vents. We had the foundation repaired and sealed the vents so now we have hardly any in the house. I just catch them and put them out the window.

Somewhat off topic, but I find roses high maintenance, too. Anything where I am supposed to coddle it or it will die over the winter is high maintenance to me. If roses overwinter on their own, fine, and the rugosa and climbing roses seem to do that. I never spray anything on the few roses I have had it my life, but I do recall one that lost most of its leaves one summer.

Marcia

Marcia: I grow nasturtiums, too. The aphids picked the zinnias first, now they've mostly moved on to the nasturtiums as well.

My ladybugs really are just starting to show up. I've only seen a few. By late summer they're plentiful and they do get into the house quite a bit.

Karen

Last year, we had a MAJOR aphid infestation on our 30ft Box Elder. The infestation seemed to pop up overnight, it was crazy. The entire tree was just crawling with aphids, sticky honeydew dripping everywhere, so gross. I tried spraying religiously several times a day, but with a tree that big it was extremely difficult. It got to the point that the tree lost a huge majority of it's leaves. But, I was bound and determined not to spray anything chemical. Then, after about a month or more of this, the beautiful, amazing ladybugs finally came, and did they KICK APHID BUTT!! It was really interesting to watch nature do her thing. The ladybug larvae truly did look like they were just vacumning the ahids up. Pretty soon, the tree was coated with ladybugs, and the aphids were gone. After their feast is over, I assume the ladybugs move onto to other areas. So anyways, that's my aphid story, hopefully it won't happen that severely again, but I very diligently place every single ladybug and larvae I come across on that tree, just in case the aphids are planning another onslaught. I've also heard that nasturtiums help attract ahids away from other plants. Good luck, I hope your ladybugs seek and destroy happily!!