A maiden is a rose that has been newly grafted. Unlike most grafted roses which are sold as #1 bushes, maidens are field grafted in summer, dug and shipped the same fall, a full year before most of the large growers harvest and ship their #1 grade roses.
The advantages to growing maidens are as follows:
You receive a dormant bare-root plant of rose rootstock, with the bud of the variety you have selected grafted and healed on the trunk (or shank) of the rootstock (see photos). When you receive your maiden rose, pot or plant it with the grafted bud slightly above the soil level.
When the canes of the rootstock produce leaves, you then cut off the whole top of the plant 1/2" above the grafted bud on the shank.
The grafted bud will then start to grow and produce the first "maiden" cane and flower usually in four to seven weeks.
The area where this first bud was grafted will eventually become the bud-union. Maiden roses when planted in the spring usually reach #1 size by fall.
Check out my growing instructions for more.