Your good old plain soil is not good enough as a breeding ground for your cannabis. Garden soil usually contains pollutants and soil borne pests, bugs and diseases. An ideal marijuana soil should not be tightly packed so water absorption will not be a problem. The most ideal potting soil contains a mixture of different nutrients necessary for the healthy growth of your weed. It is made up of seaweed or kelp which is a good source of potash and iodine, worm castings, peat moss and compost with bat and seabird droppings which are rich in urates, oxalates and phosphates. A small amount of hydrated lime or sea green and perlite or volcanic glass grains are added to act as soil conditioner and as heat insulator. Over compacted soil can suffocate your cannabis and its growth will be thwarted, hence the need for perlites and moss to allow a more balanced composition.
The organic nutrients in a quality soil mixture will suffice the required nourishment of the weeds in more than a month. After which, a minimal quantity of nutrients can be added to the water used in watering your pots. Other nutrients can be added during vegetation and flowering stages to enhance the quality of the buds further. Known high grade soil mixtures are quite prohibitive and may hurt your pocket but there are other brands which are comparable in quality but are more affordable. Be conscious of very cheap soil mixture however because it might be contaminated or very old. You just have to patiently search and look out for these brands online or from experienced growers to be assured that you will produce excellent buds and flowers.
If you are growing marijuana outdoors, it is important to enhance the plain soil with the quality mixture bought from reliable stores. It will not only perk up and fertilize the garden soil but it will improve the drainage as well. Be sure to clean the entire growing area and clear all the other weeds and eradicate all kinds of pests.
Reusing the soil mixture depends on its class but the best quality blends can be used many times over with the same good ganja results. Some low cost mixtures should be discarded after single use for it may cause harm to the pot and produce sub standard yield.
Although it is important to keep the cannabis warm, the soil should be kept moist always.