Make sure they are grafted to Poncirus Trifoliata or a hybrid of PT.

I ordered mine from Harris citrus and it is growing quite well.

Thanks. Are they best to order in spring?

I guess it depends on your winter setup. If you order now, I would make sure you repot it into the right mix (with Harris trees you will have to do that bc the pots are small) and then make sure you have adequate light for it through the winter months.

They are among the most tender of Citrus. In fact, it is the only one I over in the house (and not in my garage). Other than that, no any more difficult.