I'm never sure how big things are going to get, or if they're going to live, so I would say I underspace woody shrubs that would be difficult to move, and plant less permanent things around them in case they don't get big. And if they do I move the things that can be moved. Which reminds me, I have so much transplanting to do... nooooo.

I always assume they will grow to full size. If they don't, I can add something later. While I wait, I have lots of things to fill in the spaces with...dahlias, potted fuchsias, annuals, etc. Sometimes I have things grow quite a bit larger than they are supposed to.

I always underestimate the size of things. I thought my golden elder was going to be a shrub. NOT! And that viburnum is way bigger than i thought it would be. Another thing is Hansa, the one i moved several years ago. It has recovered so well from that move that it's about 5 feet high and at least that wide now. It's spilling over on to another bed now and i'm trying to figure out what i can do - build a wall maybe? LOL

I just realized I misinterpreted this - no, I don't plant things closer together. I try to plant things further apart than I expect to need, and plant other stuff in between that can be moved later.

Thanks everyone for your input!

I just planted the shrubs (the "backbone") in my new flower beds. I felt like I have spaced them too closely together, but then I have a few things that were really borderline hardy, so they might not get large or survive our Calgary winters.... so I am experimenting a little bit here.

I appreciate your feedback! Thanks.

I have a small yard so often I do under space plants (that is plant closer together than I normally would). Also, with some borderline hardy plants I may plant closer together. I figure if by chance they do take off and grow to their full potential, I'll deal with it at that time. I won't move a large shrub but maybe move other plants around it away or trim that shrub quite a bit each year to keep it in bounds.