by Robert Pavlis
The standard good word is to use new soil when repotting houseplants or planting containers in bound . This seems to make a set of sense . Containerized flora arise in very trivial dirt , and giving them fresh stuff should be good for them ; besides , the food in the one-time soil have been used up , and it may contain diseases .
What is potting grease ? In most case , there is very little soil in pot stain . The master factor are usually peat moss , decomposed Sir Henry Joseph Wood or coir ( ground coconut husk ) . These stuff produce a very light admixture with lots of aura for flora etymon , bear few food and tend to be weed - free .
Potted plant need to be fertilized for several reasons . The amount of soil is little and does not put up many nutrients for a crowded rootage organisation . They also dry out apace and are irrigate much more often than flora growing in the primer . This extra water flushes food out of the bay window . The amount of nutrient in new and older territory is about the same , so replacing it will not eliminate the penury for fertiliser .
Extra lachrymation can make a trouble in old dirt if you have hard water supply . punishing water contains a lot of Ca and magnesium , which will combine with fertilizer to reverse into an insoluble material that can be construe as a white deposit on the exterior of corpse pot . This is very like to the white coating you regain in your tympanum , which is calcium and magnesium left behind because of evaporation . Even if you ca n’t see it in your container , it is forming over time .
Some works , notably orchids , are very sensitive to these Strategic Arms Limitation Talks deposits . If the potting medium contains too much , root lay off arise . This is one of the reasons that orchid should be repotted every two long time and the sure-enough culture medium should not be reused for orchid . Most plants are not this sensitive to salts .
Are disease a trouble ? It is true that old potting ground can take bacterial and fungal diseases . If your plant was unhealthy , these disease can infect your new plant , but old soil from goodish plants is improbable to transmit diseases to new flora . supercede the soil with fresh uninfected dirt really does not help . If the disease spores were in the quondam bay window , they are be adrift around in the air and will quickly find your new grunge . sizeable plants are able to resist off these types of infection .
There is also talk about soil getting old . What does this imply ? In nature , grunge has been around for zillion of age . How old does it need to get before you need to supersede it ? The organic subject that makes up 99 % of soilless potting soil will decompose over sentence . As this happens , the textile is turned into nutrients and CO2,and it contains more okay atom . There will be less of it over meter , but the idea of it getting too old to grow plants has no basis .
In most cases , previous potting soil can be reused for many long time .
save by Robert Pavlis , author of three rule book , , Garden Myths , Soil Science for GardenersandBuilding Natural Ponds .
Have a question for Robert – connect on his Facebook Group : Garden fundamental principle
