In riparian settings where PLs naturally occur, root physiology is adapted to provide a pathway for O2 from the atmosphere to the roots. Roots use this O2 sourced from outside of the rhizosphere (rootzone) to fuel root function/metabolism. Plants grown in a solid medium (potting soil) have root systems adapted to use O2 from the rhizosphere. When the rhizosphere is flooded or partially flooded, the root system is functionally crippled and the entire organism suffers (spoiled/blemished foliage, poor water/nutrient uptake, poor health/growth, reduced ability to resist insects/disease [like root or crown rot], ....). Unfortunately, roots can't transition back and forth, allowing them to utilize O2 from outside the rhizosphere today and from the rhizosphere tomorrow, which is exactly what we ask them to do if we use a water-retentive soil. BTW - fading blooms should be removed from plants, but whether or not foliage you might think unattractive should be removed is a little more subjective. If your plant is healthy, you can remove leaves that are going over with very little impact on the plant's vitality; but, if the plant is weak, there are advantages to leaving the leaves on. First, we should clear up the notion that the sad looking leaves are an energy drain on the plant. They aren't. If a leaf is using more energy than it's creating, chemical messengers inform plant central that the leaf isn't pulling it's weight. At that tipping point, the plant will start 2 processes. 1) to shed the leaf lackey, and 2) while the shedding process is advancing, the plant will be salvaging mobile nutrients and other useful biocompounds from the offending leaf and translocating them to other plant parts - another way Mother Nature recycles. If your plant is struggling, you should be a little more reluctant to remove leaves until the plant signals it's done with them. Al

Spathiphyllums are tropical houseplants not lilies. You should not have them outside unless it is in the shade. Cut the sunburned foliage off, get them into shade or the house and water and fertilize.

There are lots of posts about that in the Container Garden forum. Tapla gives instructions for it in the first few comments on the post above. It's five parts pine bark fines (from dust up to 3/8" size), one part perlite, and one part peat moss. A slow-release fertilizer like Osmocote is optional. It takes some work, part of which is finding a source for the pine bark that's close to the right size, and then there's some effort involved in screening it down to remove pieces larger than 3/8" (many people just screen it to 1/4" or 1/2" since it's hard to find a 3/8" screen). You can find lots of advice about those things in the many posts about 5-1-1 in that forum. There are certainly other alternatives. Mainly I would try to get away from a close-textured peaty mixture that retains lots of water. For me, the 5-1-1 has worked perfectly and has been worth the effort. I make a batch every June and repot with it where necessary.

I've had mine go completely bone dry before finally beginning to wilt. This wasn't intentional, I only mention it to point out that the wilting isn't from underwatering. Peace lilies love water, but their roots also love fresh air, so drainage is a must. I would also advise giving it much brighter indirect sunlight. Just because some plants can tolerate low light levels, it doesn't mean that they prefer it that way. Never seek advice from a big box employee. For most of them, it's just a job; they're paid to be there. They don't care about providing accurate advice. You're better off seeking out someone shopping there that actually wants to be there. More often than not, that's where you'll find me, HaHa. I've certainly helped other shoppers whenever they needed it.