Clay pebbles can be a very economic alternative for those with home gardens. While they may not be recommended for use in large pots due to their subpar nutrient-lifting properties, they can be quite effective when used in small pots and containers. Also, unlike other fillers clay pebbles can also be rinsed and re-washed indefinitely, usually pH neutral, and their round shape allows for ample ventilation throughout the pot, aerating the roots and preventing them from rotting.
Ideally, clay pebbles should be used with net pots, especially for flood and drain hydroponic systems as the pebbles allow for the free flow of water through the plant roots and allow the nutrients to circulate better. However, a number of gardeners also make use of clay pebbles together with soil-less pot plant blends. However although it may seem like a straightforward option to place permeable substances such as clay-based pebbles in the base of the pot to ensure that water drains away more effectively. Nevertheless although it appears as if it’s a “no-brainer” choice, doesn’t necessarily work like that due to the characteristics of the pot plant blends themselves.
Regardless of whether they are put inside growing pots or in the earth, a very important factor soils and planting blends share is the fact that once the consistency or characteristics of the soil suddenly changes (for example from potting mix to expanded clay) it results in a circumstance referred to as a perched water table. This typically takes place in the bottom of your container or pot, however, if there’s clay there you’ll be essentially setting up an artificial bottom level. Typically the soil which sits on the top of the clay pebbles will stay soaked to a certain level on top of the layer of clay pebbles following watering in the same manner as it might if it had been the base of the pot.
As soon as you irrigate a pot containing clay pebbles and potting mixture, you need to completely saturate the potting soil before the excessive water may circulate to the potting soil and in to the pebbles themselves. And when you do this, the nutrient solution has filled in all of the pores within the soil or pot plant mix which was at one time filled up with air. So dependent upon the kind of soil or blend you utilize, the saturated region may take up a substantial section of the soil/mix. Therefore, the real impact of incorporating clay pebbles will be to decrease the quantity of the growing medium which you boost the percentage of saturated to unsaturated potting mix or soil.
In any sort of pot plant media, the perched water-table is going to have a depth which is very similar for that medium. For example a saturated layer in the bottom which is 1 inch deep inside a high thin container is only going to take up a small part of the entire soil mass. However, if you placed exactly the same quantity of the same type of medium inside a broad, shallow pot measuring only a couple of inches deep, it is going to take up fifty percent of the medium.
Needless to say, there are lots of technical particulars which impact the overall performance of liquid inside containers, but over-all the only real reason to put a really shallow level of pebbles at the base of the container will be to stop the potting soil or mix from washing right out of the water drainage holes any time you irrigate (and also this has stopped being even necessary in some instances).