Soil or Hydro? Which fertilizer?

By: Simon

There are too many different fertilizers and soil products and many work well. 

We don't know all of them. But basically there are two ways: in soil or in a hydro system. 

Coco fiber is an example of a hydro system in which you feed the plants by giving nutrients already dissolved in water. Soil basically contains nutrients already, bound to particles within the soil which need to dissolve in water first before the plant can take them up. A good soil has enough nutrients for a whole cycle till the end. 
Living soils are great in this respect, you only need to give water. This type of soil stays alive, a lot of micro animals live in the soil and are constantly eating dead organic material and change this into the nutrients which the plants can take up. Those soils are healthy and can be used again after a flower cycle, by adding and mixing more dead organic material through the old soil. Then it can be used again.

Most people growing in soil give nutrients already dissolved in the water anyway, basically as if you use a hydro system. But this works well too. The plants grow in the soil but use fertilizer dissolved in water. With this system you normally need to replace the soil after a cycle, because the excess artificial nutrients which are not used (dissolved in the water you give to the plants) will stay in the soil, will build up, and can after one cycle already reach a  poisonous (too high) level. Meaning there are now too many excess nutrients and waste products from the plants stuck in the soil.

If you run really clear water (distilled) through the soil you can measure how many salts (basically excess nutrients) are left in the soil, with an EC-meter. 
If low enough, EC of around let's say 1.0-1.2 you can reuse the soil again. 
If higher you need to either flush the soil with water to rinse it through, rain water would be really good for that because it is almost as clean as distilled water. Or use new soil to start the whole process again.

The higher EC in the feed water, the more build up of nutrients which were never used by the plants in the soil, because too much of them. This means: do not give too high EC when they grow in soil. I have seen people using very high EC of say 2,5-3,5 which means there are so many nutrients in the feed water that the plants cannot use them all. 

Fertilizer companies advise to give high doses, and people think that the more nutrients you give the faster a plant will grow. But that's not so. Rather it will eventually lead to an over-fed soil which will be poisonous after a number weeks. 

If you grow sativa plants which need a long flowering time you might reach the point where the plants will wilt because the total level of salts in the soil has then become higher than the level of salts in the plant tissues. The water will flow from the plants into the soil: plants will wilt and die all of a sudden.

Normally you wont reach such high levels of salts in one growth cycle. But if you use the same soil again without flushing through with clear water then this is a real scenario which could happen during your second growth cycle: all plants have suddenly wilted and are dead.

These are the basics. It is your choice how you want to grow your plants. So you can grow them in coco fiber, and use a concentrated fertilizer to mix with the water to feed them. Choose a fertilizer good for cannabis, and always choose the lowest dosage advised by the fertilizer brand. Only if the plants stay yellowish and/or show slow growth you could heighten the amount of nutrients. Too low levels may be the reason for the symptoms. But there are also other reasons why the plants cannot take certain nutrients up from the soil, causing them to show signs of a shortage of something. For example because the pH is not right and certain nutrients stay stuck in the soil at that pH ,and the plants cannot take them up. 

This means that if you want to give water with nutrients that you practically need an EC and a pH meter to be able to check your feed water. So that could be a reason to give your plants a soil which has all the nutrients already, a fertilized soil. 

With that we're back where we started: fertilized soils can be living meaning there is enough dead organic material and living micro-organisms which will constantly turn the dead material into chemically available nutrients for the plants, or an artificial fertilized soil which has chemical nutrients added. That soil is not 'alive' all nutrients should be present for a whole cycle. After one growth cycle that soil has to be changed or rinsed through after which you have to use fertilized water to use it again.

Those are the basics of plants feeding.