The Lucas formula is a way of mixing hydroponic nutrients that can help reduce the cost and complexity of growing plants hydroponically. This formula was originally designed to use 2 parts of the 3 part General Hydroponics Flora Series, which is made up of FloraGro, FloraBloom, and FloraMicro.
The Lucas Formula for General Hydroponics 3 Part Solution
The General Hydroponics Flora Series is a 3 part system that is made up of FloraGro, FloraBloom, and FloraMicro. These three nutrient solutions come in separate bottles that are usually used together with great results if you follow the instructions on the label.
The key realization of the Lucas Formula is that you can leave the FloraGro out of the mix since there is enough nitrogen, phosphorus, potassium, and trace elements in FloraBloom and FloraMicro to meet a plants nutrient requirements. That means you can skip using FloraGro altogether, which makes mixing your nutrients a little easier and more cost-effective.
So, how does the Lucas Formula work?
For each gallon of water (1 gallon = 3.78 liters) you will need to mix in 16ml of FloraBloom and 8ml of FloraMicro. This 2 to 1 ratio can also be adjusted to create a weaker solution for seedlings and cuttings which we’ll address later in this article.
Your choice of growing medium might also necessitate some modifications to the Lucas Formula. If you’re growing in Coco Coir then you can scroll further down this page for some helpful tips on how to adjust the Lucas Formula to protect your plants from certain nutrient deficiencies.
Lucas Formula MaxiBloom
General Hydroponics also makes two separate dry nutrients called MaxiBloom and MaxiGro. If you want to try a variant of the Lucas formula using only MaxiBloom (Buy Online) you can mix 7-grams of MaxiBloom in 1 gallon (3.78 liters) of water. This will give you a hydroponic solution with a nutrient ratio that is similar to the original Lucas Formula.
MaxiGro isn’t needed at all when you use the Lucas Formula with MaxiBloom, so it’s much easier to mix because you’ll only need to add a single fertilizer. Also, dry nutrients already cost less than liquid fertilizer, and since you’ll only need to buy MaxiBloom you can save a considerable amount of money.
The best way to mix MaxiBloom using the Lucas Formula is to take 7 grams of MaxiBloom and let it dissolve in a warm cup of water. You can then add the cup of dissolved MaxiBloom to 1 gallon (3.78 liters) of water. Then all you need to do is make sure the solution has a pH that’s close to 5.8 so your plants can absorb all the nutrients.
Lucas Formula FloraNova
General Hydroponics also makes the FloraNova nutrient series, which consists of FloraNova Grow and FloraNova Bloom. If you want to use the Lucas formula with FloraNova nutrients then all you’ll need is FloraNova Bloom (Buy Online).
To use the Lucas Formula with FloraNova Bloom all you’ll need to do is mix 8ml of FloraNova Bloom with 1 gallon (3.78 liters) of water. This will ensure that your plants get enough NPK and trace elements since FloraNova Bloom contains all the macronutrients and micronutrients a plant needs to develop.
Using The Lucas Formula in Coco Coir – Head’s Formula – Lucas Formula Cal Mag
If you’re using Coco Coir, you might need to adjust the Lucas formula to deal with the fact the coco coir can lead to a calcium or magnesium deficiency. The modified Lucas Formula for Coco Coir requires that you mix 1 gram of Epsom salt, 9ml of Flora Bloom, and 6ml of FloraMicro in 1 gallon (3.78 liters) of water.
Alternatively, you might be able to get away with using the regular Lucas formula in Coco if you add General Hydroponics CaMg+ (Buy Online) to your nutrient solution. If you want to try this method all you’ll need to do is follow the Lucas formula as usual. Then add 1-2 ml of CaMg+ to help increase the concentration of calcium and magnesium in your nutrient solution.
You can also use a modified version of the Lucas formula with MaxiBloom in Coco Coir if you prefer to use dry nutrients. To use MaxiBloom with Coco Coir, you’ll need to mix 1 gram of Epsom salt and 4.25 grams of MaxiBloom into 1 gallon (3.78 liters) of water.
Using Purified Water with the Lucas Formula
The Lucas formula was originally intended to be used with Reverse Osmosis (RO) water. This was meant to help simplify the mixing process, and to limit the need to measure the pH and the concentration of nutrients TDS (ppm – Parts Per Million) in the water.
In most cases, using reverse osmosis water is the only way to be sure that you’re using pure uncontaminated water. That means when you use RO water with the Lucas Formula you can be sure that you have the perfect balance of nutrients in your hydroponic reservoir.
A Reverse Osmosis Filter (Buy Online) works by forcing water through a membrane that removes any particles that are larger than 1 micron from the water. You can also get a reverse osmosis system that has a deionization filter that will strip out sub-micron chemicals that reverse osmosis membranes are unable to remove, so you end up with completely pure 0 ppm water.
Lucas Formula with Tap Water
You can use the Lucas formula with tap water, but you need to make sure you adjust the pH of the tap water to around 5.8 so your plants can properly uptake all of the macro and micronutrients from the water.
If you’re lucky enough to live in an area that has soft water you won’t have much difficulty adjusting the pH of your water. However, if you live in an area with hard water you might need to use a modified Lucas Formula.
Lucas Formula Hard Water
If you have hard water then you’ll need to adjust the Lucas Formula to compensate for the high concentration of dissolved solids and minerals in your water.
Hard water can cause trace elements to become unavailable to a plant. This is primarily because some trace elements can bind with other minerals, or they can’t be absorbed properly when you have very hard water (TDS >200 ppm).
The best way to counter this problem is to use FloraMicro for Hardwater (Buy Online) instead of regular FloraMicro. FloraMicro for Hardwater uses chelated micronutrients and trace elements that are more readily absorbable in hard water. To use Lucas Formula with Hard Water just mix 16ml of FloraBloom with 8ml of FloraMicro for Hardwater.
Lucas Formula for Seedlings/Cuttings
The Lucas Formula for seedlings or cuttings will need to be diluted until the plants are large enough to handle a full strength nutrient solution. The 2 to 1 ratio still stays the same but you only need 8ml of FloraBloom and 4ml of FloraMicro, or 3.5 grams of MaxiBloom per gallon (3.78 liters).
Using The Lucas Formula with Additives
Hydroponic additives can help promote more robust growth and enhance a plant’s flavor and aroma. It’s fine to use the Lucas formula with additives, just be sure that all of your plants are responding well to the unadulterated Lucas formula before putting any additives into the solution.