Thoughts on growing root stock

Many fruit trees that you purchase these days are grafted, mainly because they use a more durable root stock with a (perhaps) more fragile scion.  

The root stock on these trees often grows "suckers" which are typically pruned off.

I'm trying to increase the size of my orchard and I was wondering if I could just air layer some of these suckers to grow new root stock, and then graft buds from the existing scion onto this root stock?

Anyone see any obvious flaws in this idea?

Thanks.

You are generally just fine using these suckers -- those closest to the main trunk are usually the most likel to have roots that survive well.

Basic process: dig up the sucker in dormant season - make sure it has at least a few root hairs on it.  Plant  in a bed to develop its root system - it can be grafted in the spring when it starts to bud out.

The same can be done for rooted side shoots on rootstocks - cut near the trunk and as long as some root is there they tend to have high survival rate.

Taking root cuttings is also a common way (and my preferred way) to propagate pome (apples, pears, quince, etc) rootstocks. In the spring before the plant wakes up from dormancy, take a cutting of the root which is at least 6 inches long and at least one half inch wide. Be very careful not to separate the root "skin" from the woody core. Take note which end of the cutting was closest to the root crown. Plant the root cutting in soil straight up and down, making sure to leave about one inch of one end (the end which was closest to the root crown) stick out into the air above the soil. Do not let the soil dry out.