cactus in pots vs garden soil

[Gary350]

For 3 years I planted cactus in pots and in the garden. I notice the plants in pots are all small compared to plants in the garden. I have learned 2 things, plants in the garden have even root moisture all the time vs pots that dry out and stay dry until next time you water them. Also plants in the garden grow extremely long roots a tiny 10" tall cactus can have roots that cover a 5 foot diameter circle. Plants in pots have restricted roots. If I remove plants from pots it takes about 3 months for them to grow long roots but all of a sudden the cactus is growing faster than weeds. Some cactus will grow 12" a month but the same plants in pots seem to grow very little. I have noticed this in about 30 different types of cactus. It appears restricted roots in pots makes the plants stay small even if I water the pots every day. BUT the thing that makes cactus grow fastest is shade, cool weather, and good soil with continuous moisture.

[JamieUMBC]

Gary, I'm just starting out in Maryland (see attach photo). Because of the harsh winters here, sometimes near zero degrees, I'm going with potted cacti that can be brought indoors during the coldest months. Anyway, with what I've read from you about your success in Tennessee, you're an inspiration to me. In another thread, you mention watering your Giant Saguaro a little very day, and giving it a teaspoon of 20-10-10 each week. Looking at my photo, how much water do you figure is enough, on days when it doesn't rain?

Thanks,
Jamie

[rainbowgardener]

It's a general principle. Think of bonsai trees. A tree that could be 20 feet tall in the wild can be kept at 20 inches by keeping its root system tiny in a tiny pot.