I'm growing passionflowers in containers, and the soil level has been dropping. I guess the compost in the soil has been breaking down. My 5-6 gal pots now have a soil line that's about 3-4" below the rim of the containers, so I want to add 2-3" of soil to bring it to within 1" of the rim to make full use of the size of the container.
Is it okay to bury the stem/trunk of the vines like that? I know for young plants/thinner vines it's fine and they'll just grow new roots from the buried part, but I was wondering if it's still okay for thicker woodier growth that's about 1/2" to 3/4" thick. Also, some of these vines are starting to branch out from the trunk very close to the ground level, so there would be some nodes for thicker secondary vines that get buried too.
It seems like I might have to repeat the process on a regular basis, once or twice per season, due to the fact that the soil had a lot of organic matter in it.
Species I'm growing in containers include
incarnata
caerulea
manicata
tripartita (var azuayensis)
edulis
ligularis