Certified GKH Gardening Expert
Since you had that issue last year, I would go with a commercial mix that does not have fertilizer in it. All the big box brands have fertilizer in them, so you may have to go to a plant nursery to get a bag. Then you can control the amount of fertilizer, especially nitrogen, your plants are receiving. Here is how to take care of them:
https://www.gardeningknowhow.com/ornamental/bulbs/calla-lily/feeding-calla-lily-plants.htm
https://www.gardeningknowhow.com/ornamental/bulbs/calla-lily/make-calla-lily-bloom.htm
On the peacock orchid, if you grow them as annuals, you don't need fertilizer. If they overwinter or you bring them inside over winter, the next spring add some 5-10-10 slow release fertilizer as a side dressing.
https://www.gardeningknowhow.com/ornamental/bulbs/peacock-orchid/growing-peacock-orchids.htm