What you are refering to is rose balling
http://www.rhs.org.uk/advice/profiles0504/
rose_balling.asp
The website gives you good information about this. I have it happen here on occasion but not often. I find it happens to my oldest and heaviest petaled roses when the wether is rainy and no sun or air for a week or so.
Since you want to plant roses that remind you of your mother, it's the rose that will determine which one you get. If balling is a serious problem, it is preferred that you plant single to semi-double roses or roses that don't have a good deal of petals. This will help. The more petals, the better the chance of balling to occur. Also keep your distance between them liberal so there is good air flow around them. Keep them in full sun to allow them to dry out during the day. Also keep the pruned and thinned out, again to allow the best airflow in and around the bushes.
Do keep a couple of hybrid teas for your mother and see how they do. My suggestion for these would be roses such as Gemini, Dainty Bess, or any hybrid tea with 25 petals or less. The fewer the petals, the less likly balling will occur. Also with Hybrid Teas, the fewer the petals the less the fragrance. But then if they ball you can't smell them anyhow.

Wild Spice...it's name tells the fragrance.
These may not be the hybrid teas that will remind you of your mother, but may I suggest rugosa roses? Just about any rugosa that you come across will most likely do well for you. I have a real beauty here that loves moist areas and grows well in humid weather without disease or balling...Wild Spice
http://www.helpmefind.com/rose/pl.php?n=26304
Though they won't last all that long in a vase and are short stemmed, some with many prickles, they are a lovely class of roses that will take any and all kinds of weather, soil conditions and are nail hard when it comes to disease and insects. There are quite a number of varieties within this class and many of them are just as pretty (and some with better fragrance) than hybrid teas. One in particular that comes to mind is Therese Bugnet
http://www.helpmefind.com/rose/pl.php?n=21095, though I won't guarantee this girl won't ball.
I hope this helps. Keep us informed on what you decide to do and how you make out. I'm especially curious on the hybrid teas and how, keeping a larger bed with fewer roses in full sun do for you.