( and Happy New Year !!)
I usually grow non hardy aroids in containers
that are deeper, for a number of reasons.
A deeper pot helps move water through the media.
A well draining mix, while retaining moisture, should not
remain saturated. The addition of some drainage material,
for instance pot shards, aquarium gravel, pumice, etc,
will help to facilitate water moving out of the pot. If these
containers will be outside, I usually have them sitting
on a few bricks or utility tiles to ensure that water will not
wick back into the potting media.
Since you and I share similar Hardiness and weather zones,
Our summers here in the
Midwest USA, can be challenging
for growing some plants, and while they may like or
need warm weather, do not want to be soaked, as our rainy
weather can and does affect both in ground and container plantings
during the growing season.
I set out tender plants daily in spring, bringing them in at night.
Only after the danger of frost has past, do they stay outdoors
24 /7. I will incorporate a short term fertilizer, usually 90 days duration,
into the media. I do supplement this with liquid fertilizer at third
of recommended label strength, about once every 3 weeks, during
the outdoor growing season. I apply a layer of gravel or mulch to help
keep weed seeds out of the pots. I also watch for various ants, who seem to
like to move into pots, and later can move into the house, when you bring
the pots back
Once the corms have gone dormant, I check for any disease issues, clean up
any soft spots, and repot if needed.
I will attach a photo of the mix I use, which is composed of Pine Bark fines
( 3/8 of an inch ) Rice Hulls, A composted Peat Moss, some leaf mold,
and sometimes perlite. Depending on what type of plants are going to grown
in the mix, I may add an additional mineral, or even a wetting / moisture
retention product, if needed for cultural needs.