So, if I gather some seeds from my sister-in-law's tree, I could just put the in some soil on the north side of the house and they should germinate by 2008? Or should I put them in a pot?

Spacing is really a general question - that is, it applies to all plants - and the rule of thumb is to space them based on the full width. So if the mature width is 12 feet wide, they should be planted in holes that are 12 feet apart (because each "side" of the plant is only half that or 6 feet and you have the side of one plant plus the side of the next one). Plants can be pruned or shaped, certainly, to keep them in a particular size, but you should only plan to do that lightly. Jamming a 40 foot wide tree into a 15 foot space can be done, for example, but it is going to look ugly, right? But back to your specific situation. Moderate growth should have your little saplings looking pretty good in about 5-6 years; they won't grow a lot the first 2 years. They probably won't be approaching 12 foot width until they've been in place 10 years or more. As long as they are not too close to the house, I think that planting them closer than 12 feet together (like 8) won't look bad and they will form a little grove like they might have in nature. Their side branches will mingle together, a few can be removed to allow them to join more gracefully and still look good. Don't plant them in a straight line, a grouping like a triangle is a bit more pleasing and more natural. I have one in full sun and a couple others in partial sun. You'll get faster growth and more blooms in full sun if you can give them adequate water. They will also more likely reach their full potential (size wise) in full sun. Hope that helps.

Frances, I embarrassed to admit this publicly but as easy a tree as this is reported to be to grow from seed, I have failed miserably. I may try cuttings. The blue fruits ripen in early fall, and the birds love them. Timing is everything. The fruits must ripen and must be gathered before the birds clean the tree of the available treats. If you follow the procedures at the Arnold Arboretum you can get a permit and collect seeds, no charge. You can look at their plants list and locations on line. They have a number of beautiful specimens. Chionanthus retuses, is the Asain version. Ron

This is a very reliable flowering shrub for me, even following the especially difficult winter we had. Interesting flowers, wonderful fragrance, and disease resistant foliage. Fringe benefits include precociousness and long-lasting flowers. The fragrance wafts and you can smell it up to 50' with a slight breeze. Sarah, I've got to believe you'll soon see flowers.