Beginner Gardening: Limp and dying potho :( Please help!, 1 by tapla

tapla wrote:
I think it's important to the degree it's almost pivotal to proficiency that growers understand there is a direct relationship between the size of the particles a soil is made from and its water retention and the height of the perched water table. Perched water is the water that occupies the bottom of containers filled with heavy (water-retentive) soil and will not drain from the pot. It remains in the pot until it evaporates or the plant uses it.

The problem with perched water is that it begins to kill roots VERY quickly - within hours. It's not unusual for these water retentive soils to support 4 inches of perched water or more. Soils made with heavy black potting soil or topsoil, sand, peat-based container soils, compost, coir, or any combination of the aforementioned are going to support a LOT of perched water, making it very difficult for most growers to keep plants healthy, let alone coaxing them to grow at anywhere near their genetic potential. IOW - they make your job MUCH harder than it has to be.

Drainage layers do not promote drainage. Adding a drainage layer of coarse material to the pot bottom simply causes water to perch higher in the container. For example - a soil that supports 3" of perched water on top of 2" of "drainage" material simply raises the level of perched water in the container. If your container is 5" deep, the entire soil mass would remain saturated after watering thoroughly. Since the volume of air in the soil is equal in importance to the volume of water, it's very easy to see this type of scenario does not favor the plant.

What DOES favor the plant is a soil that drains very well & supports very little or no perched water at the bottom of the container. Roots LOVE air in the root zone, lots of it, and hate excess water. Since water retention and the ht of the perched water table is DIRECTLY related to particle size, the path to making it much easier to keep plants healthy and allowing a much wider margin for grower error lies in using larger particles as the primary fraction of the soil. I can't emphasize enough how much easier and more productive these types of soils are to grow in.

Soil choice is probably the most important consideration when putting together or repotting a planting. The soil is the foundation of every conventional container planting, and we all know how difficult it is to build anything lasting on a poor foundation. Even the newest newbie can pot a plant in a quality soil and get it to grow very well - every time - if they follow some very simple guidelines based on a good soil, good light, and a good nutritional supplementation program. A good soil also takes most of the guesswork out of when to water, which all but eliminates the number one killer of houseplants - over-watering.

The plant in the OP is/was suffering from ammonia toxicity (which was probably its undoing) and probably plasmolysis, which is a technical term for fertilizer burn due to the high level of solutes (dissolved solids) in the urine. Fertilizer burn occurs not only from over-fertilizing, but from a high level of anything dissolved in the soil solution - sugar can cause it as easily as fertilizer or table salt. Cat urine is also very basic (opposite of acidic) and can cause severe nutritional disorders and other problems if not corrected immediately.

Al