Evan,
Yes, if the soil is dry, moisten it first before applying liquid fert. If the plant roots are already stressed from dry soil, you do not want to aggravate it by adding fert.
Ed,
I use both because i don't know how acid a medium Caladiums will tolerate, so i just want to get it on the acid side of neutral, especially since well water here is alkaline. I cannot comment on the use of a soil mix formulated specifically for acid loving plants as I mix my own. Though I have never tested the pH, based on the ingredients i surmise that the pH is near neutral.
As for the mix strength of the Miracle Gro solution, what I actually use is the 1 teaspoon per 5 gallons. For heavy feeders, like large Alocasias, you can go to the 1/4 strength, but i wouldn't go any stronger than that (assuming you have Nutricote in you soil). It is possible that Caladiums could tolerate a little stronger mix, but so far I have had good success with my regime.
Regarding Nutricote, when mixing my soil medium I use 2 cups for about 2 cu ft of mix. I don't know how that figures in grams, but it works for me and i use it as a general mix for many kinds of plants, especially aroids. For large growing Alocasias, you could use a little more and I'm pretty sure it wouldn't hurt, but since my mix works fine for me, I don't want to mess with success.
Washed perlite is one of the main ingredients in my soil mix, so i recommend using it, particularly if the soil mix is on the heavy side without it. I rinse the dry perlite through before use to eliminate the dust and fluorides that are present in the product.
Interesting about your experience with starting the Caladiums early in a warm room; I had over 75% blooming on my plants so that is not a problem- Now, when it comes to Thai Caladiums, you might need that warm room for the whole winter as they do not do well when exposed to cool temperatures. I just pointed out that in hybridization, blooms are of primary importance so proper feeding during the growing period is important to grow good tubers for next year.
LariAnn
