Question
I recently planted three cacti in a six inch standard terra cotta pot.  There is one
cactus (3" H) that looks health it just keeps falling over.  I tried repotting it but
the problem persisted.  The plant has both limited water and plenty of
sunshine.  How can I get it to stand up straight?

Answer
Wayne,

That depends, is it bending over or is it falling over? If is bending over, that means one of 2 things, either it is supposed to creep along the ground (common in some cacti) or the stem is weak. In that case, you can stake it up.

If is falling over, it may not be planted deep enough in the soil. Try planting it a little deeper. Water right after you plant it and as the soil dries, it should be able to support the plant. Hope this helps.

Sincerely,

Greg