Best soil mix for an Arrowhead Vine in a self-watering planter?
There is an arch above my living room which I would like to decorate with several Arrowhead Vines, but I have very little experience with houseplants and I need some advice before I even attempt to pot them. Since the area is somewhat out of reach, I purchased three large self-watering planters to limit the frequency at which I'll have to break out the step stool to water the plants. (I read that I will still need to water them from above on occasion even though there is a reservoir, though I'm not sure how often I should do this.) The planters are those Mayne Fairfield window boxes that are mostly intended for outdoor use, and since houseplants don't seem to be a common application for this type of planter I'm wondering if the reservoir/trough watering style might effect which type of potting mix would be best. Should the capillary action which will allow water to soak upward from the bottom of the planters be a factor in selecting a potting mix, or is the ideal potting mix for Arrowhead Vines the same regardless of whether or not they receive most of their water from the surface? And what is the ideal mix? Also, the instruction packet for the planters also recommends using a layer of lightweight filler in the bottom third of the planter, beneath the actual potting mix, "to encourage faster root growth down into the troughs." Anyone have an opinion about which filler material might work best for an Arrowhead Vine growing in this type of planter?
Thanks so much for any advice!