Fred P, that makes me feel a little better. But wouldn't we be wanting carbon dioxide to reach the roots, not necessarily oxygen (obviously both are in air)?
No, you really want oxygen to reach the roots. Everyone knows how important carbon dioxide is to a plant but very few know how important oxygen is to the overall health of a plant. Oxygen helps the roots absorb nutrients at a faster rate and can significantly increase the overall growth rate of the plant. The leaves of a plant have easy access to oxygen. They make it as a natural bi-product and breathe it out as waste during the process of photosynthesis. The roots of a plant do not have the same amount of oxygen available to them. They have to work a lot harder to find enough for their needs. The lack of oxygen at the roots will reduce the plants root respiration and result in the roots turning brown and ultimately shutting down the photosynthesis process. A nice white root system is a sign the plant is receiving adequate oxygen at the root level. A plant’s growth is controlled by the size and health of its root system. It can only grow to its full potential if the roots have enough oxygen for their needs. By top watering, it allows oxygen to be pulled through the soil to the roots. The more porous your soil is, the more oxygen can pass through it. Which was a winded explanation of why I use perlite. These are some of the root systems I unpotted this past winter using the mixture above.
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I have used a 1:1 compost of sphagnum peat moss to horticultural sand for several years, since I have a deep, abiding hatred of perlite. Also, that additional "ballast" of the sand prevents the otherwise top-heavy pots from tipping over in the wind . . .
Sarracenia leucophylla cv. "Titan" 2009
Nice 'Titan' BTW BB.
The first pic above is of my Titan's root system.