Your collection are really lovely. In our country, there are also many people interested in ASTROPHYTUM.

In my opinion, I do not think that it is a good idea to graft althought it can make flowering and seeding more. but it also can speed up caducity and influence the exterior. I prefer growing it from seed, the process of its growing is the most interesting.

By the way, I come from China. It is luckly to find such useful forums and so many nice people who have the same interest with me. As I am a student, I try to express my opinion in English. Althought I still have some problems, but I am getting better. Thanks.

G'day extremeflora

I am an Astrophytum collector and living in Adelaide, South Australia. Winter in here is moderate, no snow and no ice. It will be quite different climate from Washington DC but I think:
1. Both of grafted and own root cactus may not go dormant if you used grow lights and fed water.
You should not do that.
Both of grafted and owm root cactus should go dormat in winter. I force cactus to go dormat by cutting water feed in winter. Spring flowering will be poor if cactus grew in winter.
2.The growing condition of a grafted cactus should be met with the root stock, not with the scion.
A grafted Super kabuto and an own root Super kabuto should be treated differently, as like different plants.
Altough above mentioned, both of ones should go dormant in winter.
3. I feed water once per month on a warm day to own root Super kabut in winter as same as grafted cactus.
Hylocereus are used as root stocks for some of your grafted cactus. Winter tolerance of Hylocereus is very poor. You may stop to feed water to Hylocereus in winter.
Hylocereus is also not a permanent root stock. You have to degraft the scion someday.

I have about 500 grafted and 2000 own root Astrophytums including 500 Super kabutos.

Frank