Online landscape design
The best program for this is Google Sketchup. Why? Because the purpose of it is to easily let you draw in 3D, meaning a perspective view, rather than the view from above.

There is a free version. There is also a professional version which I use, but most homeowners do not need that.
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Depending on your ability, it can be very easy or slightly challenging. However, I would give it a try. It's a lot of fun. 

Since you are concentrating on a bed in front of your house, or a foundation planting, you will want to draw in your house. This does not have to be exact. However, I would put in the length of the house and correctly locate the windows and doors at the least. 

After you select plants, which are called components, you can adjust their size.

I hope this is helpful. Here is the link. Sketchup