RoYalQuEenChEeSe
Active Member
[h=1]Fertilising Smart Guide[/h]Fertilising belongs to one of the most important gardening duties - especially outdoor and, of course, in hydroponics too. Yet many cannabis cultivators do not know when the right time is to fertilise, how much to use, or how often. This is in part also caused by the lack of information supplied by the companies selling the fertiliser. To further complicate matters the recommended dosages are often quite confusing and tempt customers to use large amounts of fertiliser! If cultivators lack experience or, despite a good amount of gardening knowledge, they cannot find the cause of certain plant symptoms, it is very likely that they are constantly over-fertilising the plants.
To put an end to this negative trend, and because strains grow perfectly well with only small amounts of fertiliser, following these guidelines fertilizing your plants can become a secure routine and not a matter of life and death for your plants.
[h=1]Essential Knowledge About Nutrient Dosage[/h]Let's start with the small print on the bottles which your would generally use as orientation for mixing your nutrient solution.
What many do not know: the recommended EC value is always based on osmosis water with an EC of 0.0 mS/cm!
Canna and other Dutch companies generally recommend even higher values. So the necessity of being aware of this formula is quite apparent. Although one really must ask how the plants should survive long term on levels of 2.0 2.2 mS/cm, most customers actually use such strong dosages in their grow because they are unaware of this essential information. The result is not only a waste of fertiliser in hydroponic systems. Plant care also becomes much more complicated and problematic. Regular flushing with water or weak nutrient solution are necessary at such high EC levels in hydroponics. On the one hand, the plants grow very fast (they stretch, get leafy, etc.), and, on the other hand, they develop complex symptoms of over- and under-fertilisation from the high salt content in the substrate.
In the end massive overdoses of nutrients lead to a high risk of mold in the flowering phase, reduced levels of resistance against pests, lower yields, male flowers on females, and possibly pose a health risk from radioactive traces in the cannabis (from phosphate).
For the cultivation in soil there is a common rule among cultivators to use 50% of the recommended dosages. Growers follow this rule without actually knowing what salt concentration they are feeding their plants with. For soil cultivation an EC meter is the most important tool to find out what the proper dosage is. This is why everyone who values their plants should not save on this rather moderate investment of 45$/Euro!
[h=1]Testing Dosages Given by The Industry[/h]To demonstrate how important the EC level is we have tested 5 popular types of fertiliser. Only the fertiliser for flowering was selected because during this phase growers fertilise the most (after the motto: more fertiliser = more yield). Yet during this part of the life cycle plants become increasingly sensitive to excess mineral salts.
Before we look at the results it is important to understand one thing: generally one should never fertilise more than 0.8 mS/cm on soil. You can fertilise up to 1.2 mS/cm if you have to quickly reverse deficiencies in adult outdoor plants. It is better to fertilise with a medium range and repeat the treatment after a week or so, rather than starting with a heroic dosage that can be difficult for the plants to cope with all at once.
The first important step is to find out what the EC of your tap water is. In this example we are using a 50-50 mix of reverse osmosis water and normal tap water to get 0.43 mS/cm. Obviously, if you have a value over 0.8 in your tap water you have to lower the EC level through filtration. For small gardens it's sufficient to use a Britt Filter if you do not have the money to buy a household reverse osmosis filter (approx. 100$/Euro). The Britt filter can reduce the EC level by 0.15-0.20 mS/cm. Another alternative would be to buy 5L/1 gallon bottles of non-carbonated mineral water when you fertilise. Good mineral water has approx. 0.25 mS/cm.
Here are the test results on our water with EC 0,43 mS/cm for 5 popular products (measured on Hanna Dist 3 meter). All values are in milliSiemens (mS/cm).
General Hydroponics
One Part Bloom (N-P-K: 2-4-7)
Recommended min. dosage (Hydro): 8ml/1L or EC 1.5 mS/cm
Recommended dosage on soil: "less" (?!)
Recommended frequency on soil: every second watering
2ml/1L = 1.30 EC
4ml/1L = 2.00 EC
0,5ml/1L= 0.70 EC
The amazing thing about these instructions is the inaccuracy of the amount to fertilise on soil. What does "less" mean? If we were to use the common rule and mix 50% of the recommended dosage we still get an EC of 2.0 mS/cm! That would lead to immediate symptoms of overfertilization. Even at 25% of the dosage we are still in the danger zone. With 0,5ml/L or 6% of the recommended dosage we finally have a safe solution! This example shows how important it is to have an EC meter at hand.
Canna
Terra Flores (N-P-K: 10-9-19)
Recommended dosage: 5ml/1L
Recommended frequency: 1-3 x weekly
5ml/1L = 1.83 EC
2ml/1L = 1.05 EC
1ml/1L = 0.76 EC
Out of interest we tested the dosage of 5ml/L. If you were to give your plants this dosage they would not be very happy about it. Surprisingly, the manufacturer recommends this high salt level for soil cultivation a level that is not even used in most hydroponic cultivation! The ratio of nitrogen and potassium is quite dangerous in this fertiliser. Both minerals are present in high amounts but flowering cannabis plants cannot store excess N and K as easily as phosphorous and magnesium. At 20% of the recommended dosage we can water with a safe nutrient solution.
Ionic
Bloom (N-P-K: unknown)
Recommended min. dosage (Hydro): 7ml/1L
Recommended dosage for soil: 1,0 ml
Recommended frequency: no info
3,5ml/1L = 1.62 EC
1 ml/1L = 0.81 EC
At least the manufacturer offers an EC value for soil cultivation. But, again, if you don't have an EC meter and mix 50% of the dosage the plants are over-fertilised. At 15% we found the correct dosage. The downside is that the N-P-K values are not disclosed on the label which is below standard.
AlgoFlash
Flower (N-P-K: 4-6-7)
Recommended dosage: 4ml/1L
Recommended frequency: every second watering
2ml/1L = 1.38 EC
1ml/1L = 1.00 EC
0,5ml/1L = 0.75 EC
This concentrated fertiliser is a good choice for cannabis cultivation but it is also dangerously potent. Even half the dosage is still too strong and it has to be diluted to 12,5% before we get the ideal value of 0.75 mS/cm. If you have a higher EC level in your tap water you can water with only 10% and get good results.
All recommended feeding frequencies on soil for the fertilisers in our test are incredibly high. This is a general trend among manufacturers. Growers who follow the advice on the bottle or "feeding chart" automatically cause damage to their plants - even if these are not immediately visible for an inexperienced or untrained grower.
[h=2]
Feeding frequency on soil[/h]Apart from the actual salt concentration of the nutrient solution the frequency and amount you water is an important aspect.
Generally, cannabis plants prefer small but regular feedings if they require extra fertilisation. "Small" means in our case a moderate level of 0.6 mS/cm (indoor) to 0.8 mS/cm (outdoor). You can compare fertilizing to real mealtimes. People also get a stomach ache when they overeat. It's much healthier to eat small meals regularly. In the same way cannabis appreciates getting small portions of nutrients that can be "digested". So watering high dosages of fertiliser is like force feeding. But plants aren't pigs that have to be fattened.
With a nutrient solution of 0.6-0.8 mS/cm you can't do much wrong unless you make a mistake with the feeding frequency or amount of nutrient solution. That's why it´s important to wait 7-10 days after fertilizing and observe the plants. How are they taking up the nutrients? Do they need a bit more or are they looking healthy enough? A slight deficiency can be easily levelled out with one mild feeding (and does not impair flowering) but overfertilization causes irreparable damage. As you learn to observe the plants you will develop an intuitive understanding and can read small signs of nutrient deficiency that signal the best time to apply a mild nutrient solution.
[h=1]What you should watch out for[/h]Soil and containers
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]The quality of the soil and size of containers decides a great deal about the nutrient needs of your plants. If you use strongly pre-fertilised soil it´s possible that your plants don't require any additional feeding till harvest! A good example are organic grows that use composted material with a high mineral content (like manure, etc.). Some manufacturers sell very potent soil mixes that are almost toxic in their pure form. An example is All-Mix from Plagron which has an EC of 2.4 mS/cm! If your containers are too small compared to plant size or maturity you will find that your plants quickly suffer from nitrogen deficiency. Another factor is light intensity. A fluorescent grow cannot be compared to a sodium vapour grow. More light means bigger plants and higher nutrient requirements.[/FONT]
Watering amount
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]Not only the EC but also the amount of nutrient solution determines salt levels in the soil. The amount you water should not exceed the normal requirements of the plant. If an adult cannabis plant in your garden uses 500 ml water daily then you should water that same amount or less with the nutrient solution. Never fertilise on dry soil![/FONT]
Outdoor
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]Outdoor the quality of the soil, plant size, and climate play an important role in nutrient uptake. It's best to fertilise when warm/sunny days are predicted so that the plants can transform the nutrients directly into growth. Due to plant size the most common deficiency is nitrogen. This deficiency is easy to detect: first the leaves lose their leaf shine and become dull, then the lower sun leaves start to yellow, these symptoms gradually move upward and affect more leaves, in advanced stages the lower leaves dry up and die and the plant has yellowed up to the shoot tips. A flowering fertiliser with an adequate amount of nitrogen should be used when nitrogen deficiency appears during or after sexing. When a deficiency is already apparent you can use a higher EC of about 0.9-1.0 mS/cm to compensate the low level of nutrients quickly.[/FONT]
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]The second most common deficiency is phosphorus which is required in large amounts for root and bud growth. Phosphorous is stored generously in plant tissue so that if you have an intelligent feeding plan the plants will get enough phosphorous to last till harvest even when feeding stops about 2-3 weeks beforehand.[/FONT]
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]I thought this makes a good read and may help someone not my work might be useless so make your own mind up!!![/FONT]
To put an end to this negative trend, and because strains grow perfectly well with only small amounts of fertiliser, following these guidelines fertilizing your plants can become a secure routine and not a matter of life and death for your plants.
[h=1]Essential Knowledge About Nutrient Dosage[/h]Let's start with the small print on the bottles which your would generally use as orientation for mixing your nutrient solution.
What many do not know: the recommended EC value is always based on osmosis water with an EC of 0.0 mS/cm!
- Example: Ionic recommends an EC of 2.0 mS/cm for flowering in hydroponics. From this value the cultivator must deduct the EC of the tap water in order to calculate the actual recommended dosage.
Let's say your water has an EC of 0.6 mS/cm. Then you calculate 2.0 0.6 = 1.4 mS/cm.
The recommended maximum dosage is therefore 1.4 mS/cm.
Canna and other Dutch companies generally recommend even higher values. So the necessity of being aware of this formula is quite apparent. Although one really must ask how the plants should survive long term on levels of 2.0 2.2 mS/cm, most customers actually use such strong dosages in their grow because they are unaware of this essential information. The result is not only a waste of fertiliser in hydroponic systems. Plant care also becomes much more complicated and problematic. Regular flushing with water or weak nutrient solution are necessary at such high EC levels in hydroponics. On the one hand, the plants grow very fast (they stretch, get leafy, etc.), and, on the other hand, they develop complex symptoms of over- and under-fertilisation from the high salt content in the substrate.
In the end massive overdoses of nutrients lead to a high risk of mold in the flowering phase, reduced levels of resistance against pests, lower yields, male flowers on females, and possibly pose a health risk from radioactive traces in the cannabis (from phosphate).
For the cultivation in soil there is a common rule among cultivators to use 50% of the recommended dosages. Growers follow this rule without actually knowing what salt concentration they are feeding their plants with. For soil cultivation an EC meter is the most important tool to find out what the proper dosage is. This is why everyone who values their plants should not save on this rather moderate investment of 45$/Euro!
[h=1]Testing Dosages Given by The Industry[/h]To demonstrate how important the EC level is we have tested 5 popular types of fertiliser. Only the fertiliser for flowering was selected because during this phase growers fertilise the most (after the motto: more fertiliser = more yield). Yet during this part of the life cycle plants become increasingly sensitive to excess mineral salts.
Before we look at the results it is important to understand one thing: generally one should never fertilise more than 0.8 mS/cm on soil. You can fertilise up to 1.2 mS/cm if you have to quickly reverse deficiencies in adult outdoor plants. It is better to fertilise with a medium range and repeat the treatment after a week or so, rather than starting with a heroic dosage that can be difficult for the plants to cope with all at once.
The first important step is to find out what the EC of your tap water is. In this example we are using a 50-50 mix of reverse osmosis water and normal tap water to get 0.43 mS/cm. Obviously, if you have a value over 0.8 in your tap water you have to lower the EC level through filtration. For small gardens it's sufficient to use a Britt Filter if you do not have the money to buy a household reverse osmosis filter (approx. 100$/Euro). The Britt filter can reduce the EC level by 0.15-0.20 mS/cm. Another alternative would be to buy 5L/1 gallon bottles of non-carbonated mineral water when you fertilise. Good mineral water has approx. 0.25 mS/cm.
Here are the test results on our water with EC 0,43 mS/cm for 5 popular products (measured on Hanna Dist 3 meter). All values are in milliSiemens (mS/cm).
One Part Bloom (N-P-K: 2-4-7)
Recommended min. dosage (Hydro): 8ml/1L or EC 1.5 mS/cm
Recommended dosage on soil: "less" (?!)
Recommended frequency on soil: every second watering
2ml/1L = 1.30 EC
4ml/1L = 2.00 EC
0,5ml/1L= 0.70 EC
The amazing thing about these instructions is the inaccuracy of the amount to fertilise on soil. What does "less" mean? If we were to use the common rule and mix 50% of the recommended dosage we still get an EC of 2.0 mS/cm! That would lead to immediate symptoms of overfertilization. Even at 25% of the dosage we are still in the danger zone. With 0,5ml/L or 6% of the recommended dosage we finally have a safe solution! This example shows how important it is to have an EC meter at hand.
Terra Flores (N-P-K: 10-9-19)
Recommended dosage: 5ml/1L
Recommended frequency: 1-3 x weekly
5ml/1L = 1.83 EC
2ml/1L = 1.05 EC
1ml/1L = 0.76 EC
Out of interest we tested the dosage of 5ml/L. If you were to give your plants this dosage they would not be very happy about it. Surprisingly, the manufacturer recommends this high salt level for soil cultivation a level that is not even used in most hydroponic cultivation! The ratio of nitrogen and potassium is quite dangerous in this fertiliser. Both minerals are present in high amounts but flowering cannabis plants cannot store excess N and K as easily as phosphorous and magnesium. At 20% of the recommended dosage we can water with a safe nutrient solution.
Bloom (N-P-K: unknown)
Recommended min. dosage (Hydro): 7ml/1L
Recommended dosage for soil: 1,0 ml
Recommended frequency: no info
3,5ml/1L = 1.62 EC
1 ml/1L = 0.81 EC
At least the manufacturer offers an EC value for soil cultivation. But, again, if you don't have an EC meter and mix 50% of the dosage the plants are over-fertilised. At 15% we found the correct dosage. The downside is that the N-P-K values are not disclosed on the label which is below standard.
Flower (N-P-K: 4-6-7)
Recommended dosage: 4ml/1L
Recommended frequency: every second watering
2ml/1L = 1.38 EC
1ml/1L = 1.00 EC
0,5ml/1L = 0.75 EC
This concentrated fertiliser is a good choice for cannabis cultivation but it is also dangerously potent. Even half the dosage is still too strong and it has to be diluted to 12,5% before we get the ideal value of 0.75 mS/cm. If you have a higher EC level in your tap water you can water with only 10% and get good results.
All recommended feeding frequencies on soil for the fertilisers in our test are incredibly high. This is a general trend among manufacturers. Growers who follow the advice on the bottle or "feeding chart" automatically cause damage to their plants - even if these are not immediately visible for an inexperienced or untrained grower.
[h=2]
Feeding frequency on soil[/h]Apart from the actual salt concentration of the nutrient solution the frequency and amount you water is an important aspect.
Generally, cannabis plants prefer small but regular feedings if they require extra fertilisation. "Small" means in our case a moderate level of 0.6 mS/cm (indoor) to 0.8 mS/cm (outdoor). You can compare fertilizing to real mealtimes. People also get a stomach ache when they overeat. It's much healthier to eat small meals regularly. In the same way cannabis appreciates getting small portions of nutrients that can be "digested". So watering high dosages of fertiliser is like force feeding. But plants aren't pigs that have to be fattened.
With a nutrient solution of 0.6-0.8 mS/cm you can't do much wrong unless you make a mistake with the feeding frequency or amount of nutrient solution. That's why it´s important to wait 7-10 days after fertilizing and observe the plants. How are they taking up the nutrients? Do they need a bit more or are they looking healthy enough? A slight deficiency can be easily levelled out with one mild feeding (and does not impair flowering) but overfertilization causes irreparable damage. As you learn to observe the plants you will develop an intuitive understanding and can read small signs of nutrient deficiency that signal the best time to apply a mild nutrient solution.
[h=1]What you should watch out for[/h]Soil and containers
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]The quality of the soil and size of containers decides a great deal about the nutrient needs of your plants. If you use strongly pre-fertilised soil it´s possible that your plants don't require any additional feeding till harvest! A good example are organic grows that use composted material with a high mineral content (like manure, etc.). Some manufacturers sell very potent soil mixes that are almost toxic in their pure form. An example is All-Mix from Plagron which has an EC of 2.4 mS/cm! If your containers are too small compared to plant size or maturity you will find that your plants quickly suffer from nitrogen deficiency. Another factor is light intensity. A fluorescent grow cannot be compared to a sodium vapour grow. More light means bigger plants and higher nutrient requirements.[/FONT]
Watering amount
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]Not only the EC but also the amount of nutrient solution determines salt levels in the soil. The amount you water should not exceed the normal requirements of the plant. If an adult cannabis plant in your garden uses 500 ml water daily then you should water that same amount or less with the nutrient solution. Never fertilise on dry soil![/FONT]
Outdoor
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]Outdoor the quality of the soil, plant size, and climate play an important role in nutrient uptake. It's best to fertilise when warm/sunny days are predicted so that the plants can transform the nutrients directly into growth. Due to plant size the most common deficiency is nitrogen. This deficiency is easy to detect: first the leaves lose their leaf shine and become dull, then the lower sun leaves start to yellow, these symptoms gradually move upward and affect more leaves, in advanced stages the lower leaves dry up and die and the plant has yellowed up to the shoot tips. A flowering fertiliser with an adequate amount of nitrogen should be used when nitrogen deficiency appears during or after sexing. When a deficiency is already apparent you can use a higher EC of about 0.9-1.0 mS/cm to compensate the low level of nutrients quickly.[/FONT]
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]The second most common deficiency is phosphorus which is required in large amounts for root and bud growth. Phosphorous is stored generously in plant tissue so that if you have an intelligent feeding plan the plants will get enough phosphorous to last till harvest even when feeding stops about 2-3 weeks beforehand.[/FONT]
[FONT=Trebuchet MS, Arial, Helvetica, sans-serif]I thought this makes a good read and may help someone not my work might be useless so make your own mind up!!![/FONT]