How many double knockout roses for 17' foundation?

If they grow up to 4' wide, would planting four right under the picture window be enough? Or is that a big "no no" since it's not an odd number? I want it to eventuallly grow to hide the left and right corners. Thanks!

Planting in odd numbers is just a rule of thumb for making groups of plants look good. But it doesn't really apply to things planted in rows. Your best bet is to plant the right number of plants for the space you have. Therefore, four plants will do the trick. Besides, once they start to grow together you won't be able to tell it's four plants anyway.
If the idea of an even number still bothers you plant three roses further apart and then plant something lower slightly forward to cover the negative spaces. This might be a good idea for you anyway because the roses will look rough from at least November through February so for the lower tier you could plant something evergreen.

Hi I do so called professional landscaping,,if it was me I would plant 5 knock out roses,,or maybe even seven if you stagered them ,,one up one back and so on,,just an idea!!!

It is rarely a good idea to crowd plants, especially roses. And although the Knockout series is disease resistant it still is possible for them to get black spot and powdery mildew; I've seen it firsthand. Also keep in mind that the roots will only be able to grow away from the foundation and if they are too close to one another they won't have enough room to grow into which will lead to root competition. Now that Knockout roses have been around for a few years they've grown bigger than most people guessed they would. I've taken a picture of one that is at least 4' tall and 5' wide.

I purposely chose not to be a landscaper. Instead I work at a nursery where I try to focus my customers attention on what the plants want and need. This ensures the plants' performance and ultimately the customers happiness with the plants. In my spare time, I do landscape consultations for our customers during which I tell them how to fix the multitude of problems that their professionally done landscape has led to.

I'm with plantfreak, when you're planting things all in a row the 3/5/7/etc is not as important, I think it's more important to have appropriate spacing between the plants. Or if you want to follow the rule of odd numbers, then I'd plant 3 of them and have a little more space in between them, maybe they'll fill in that area anyway or if not you can put some tall perennials in between or something

I have made a hedge out of several knock out rose planted together I only have to prune once in a while but never really have to spray for anything,and they do great but they are planted out in the open were they do get alot of flow of air,so I guess this wont work by a house not having enough air flow going threw them you might run into black spot!!! just my thoughts!

Usually, placing things in odd numbers is more aesthetically pleasing in all areas of design.

However, with the knockout roses, in my short experience, they have grown so quickly, I think it almost wouldn't matter. They'll just look like a solid hedge so quickly.

We're total newbies (first-time homeowners as of last Dec.) and we planted 2 knockout roses in our flowerbed, right in front of our house, about 2.5 feet apart....just to try them out and see how they grew, and we could not believe it! After just a month and a half they had almost doubled in size. We've had a drought all summer and they have still bloomed constantly. The growth they have had has been absolutely amazing. I'm excited to see what they do next year.

Also, a lot of my neighbors have them too. Since this is a brand new subdivision, I know they have not been there more than 2 years and they are quite big already.

I wouldn't worry about the odd number thing. You have to make sure you plant themfar enough apart so you have good air circulation. For 17 ft I would plant 4, those babies will grow. The best thing to do is set them in your area and see how they look. Too many people want instant gratification and pay in the end. I'm always going to clients houses and fixing their problems. Think about the recommendation of spacing, if they say for do for if you want more then go 3ft but no more. If it were me, i'd go 4.

Hey, not to mess up your plan, and maybe I don't know what I'm talking about, but won't the knockouts be kind of boring and/or leafless in the winter, or do they keep their leaves? I've only grown floribunda roses which lose alot of their leaves, and you have to prune them each spring. I think you're also supposed to prune knockouts regularly. If so, they may look sparse at the beginning of every growing season. I personally am trying to come up with a similar solution for my house, where I want to replace some half-dead boxwoods in front of some windows right up against my house. I am considering different evergreen shrubs that look good all year and don't need yearly pruning.

I'm with erdooley on this one. I would definitely use something evergreen as a foundation plant on the front of my house. Doesn't mean you couldn't put a row of roses in front of that, just that winter is going to be looking pretty sad in the front of your home with nothing but dead sticks.
You don't have to use conifers- there are all sorts of broadleaf evergreens you could consider. And a nice deep multi- layered bed looks nicer than plain rows, too- IMO.