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Dwc cannabis breeding for seed

Germinate Seeds for DWC (Hydroponic Germination)

This guide will show you how to germinate seeds for DWC (Deep Water Culture) growing.

Starting from clones is much easier than starting from seed when it comes to DWC. Seeds are fragile and require extra care when being propagated for hydroponics. This is probably the one area where soil growers have an edge over DWC. Since soil typically contains trace nutrients simply plopping a seed in moist soil is usually all it takes to get a healthy 3-4″ plant.

Materials Required for DWC Germination:

Paper Towel Germination

Start your DWC germination using a moist paper towel. Wet 2-3 sheets of paper towel using tap water. I don’t bother with adjusting pH this early into the grow. Ring the paper towel out so that it is moist but not dripping.

4.4g dry weight, 35g wet weight for the nerds out there

Spread the seeds out over the paper towel and fold over so that the seeds are sandwiched by at least two layers of paper towel. Work with clean hands and minimize air exposure after soaking.

Put this somewhere warm, 80F is ideal for germination but in my experience, anything above 65F will work fine.

Top of the fridge is an oft-recommended spot but when I actually tested surface temperatures in my house the top of my fridge was about 5 degrees colder than the top shelf in my pantry

If you live in a very cold climate like me and my fellow Canadians you can put the seeds in the oven with the light on to generate a bit of heat. Goes without saying you should put a sign up if you are using the oven method!

After 1-2 days the seedlings should crack and the taproot will begin growing. Leave them a few more days.

After 3-5 days the taproot should be over 1″ long. This is when they are ready for transplant. The seeds were a freebie so I’m ok with the 66% success rate. Typically, you should have 90% or greater germination rate for high-quality genetics.

Rockwool Sleeve

EDIT: Since writing this post I have tried inserting the rooted seedling directly into the foam collar and found it works just as well. IMO the rockwool sleeve is not necessary.

What I do next is something I came up with out of necessity. A full rockwool cube I find to be unnecessarily large. If you’ve read my DIY Cloner article you’ll know that I feel Rockwool can create a low oxygen environment where pathogens thrive.

Rockwool serves a purpose for hydroponics germination. It helps protect fragile taproots and holds water between spraying.

Start by soaking your Rockwool in pH 5.5 water.

Take a Rockwool starter plug and cut it into 4 long strips. Use a clean knife to cut a slit in these strips.

Place the germinated taproot into the slit that you created.

Rockwool Sleeves for Foam Cloning Collars

As per my DIY cloner article I prefer foam collars over neroprene. The foam holds up better and surprisingly absorbs less water.

Trim the foam collar to create room for the Rockwool sleeve

Aeroponics Cloning Nutrient Solution

  • 1 Gallon Water (Target pH 5.5) (1 mL each Micro, Gro & Bloom)
  • 1.2 mL of Rapid Start

A few drops of pH Down gets me down to 5.5

Unlike soil (which has trace nutrients) cloning/germination in hydroponics requires immediate additions of nutrients. Once you get the pH to 5.5 add:

  • 1.2 mL GH Rapid Start
  • 1 mL of FloraGro
  • 1 mL of FloraMicro
  • 1 mL of FloraBloom

My starting ppm was 100 and the final ppm was around 300.

Seedling Growth

From here the process is the same as with clones. Simply run the pump on a cycle timer and let nature do its work.

The plants will not look happy on day one, but don’t worry they will perk up quickly under the light.

Rockwool Watering (Why I started using aeroponics for germination)

aeroponics cloner I needed to water the seedlings multiple times per day, even with the humidity dome! You can also see why I have the plants so close to my light now. Fluorescents are not very strong and can cause extreme stretching if they are not within a few inches of the plants.

How to grow cannabis plants in clay pebbles

Expanded clay pebbles are a widely used growing medium in the world of hydroponic cultivation. It’s a lightweight, roughly spherical, red ceramic aggregate with a high iron content. Before it can be used, it must undergo several different processes during manufacture. The most important of these steps is heating at extremely high temperatures, causing the rapid expansion of the clay and trapping air in pores within the odd-shaped balls. Clay pebbles have many uses besides hydroponic growing, also being widely used in construction as lightweight aggregate and thermal insulation, etc.

The size of clay pebbles can vary from 5 mm for the smallest to 15mm for the very largest kind. It must be noted that bigger clay pebbles will retain moisture more easily and for a longer time than those of smaller size.

In this post we will focus on explaining how to properly employ clay pebbles in cannabis cultivation and avoid any potential problems using this hydroponic culture medium.

Buds grown in clay pebbles

Which growing system to use with clay pebbles?

There are many different hydroponic growing systems, so, first we must make clear which type of cultivation system is suitable for use with clay pebbles. This substrate basically allows us to use one of two irrigation methods in recirculating hydroponic systems; flood & drain (ebb & flow) or drip-feed irrigation into a plant pot or tray.

Cleaning and stabilising clay pebbles before use

Expanded clay pebbles are non-sterile and can often contain residues and impurities. Theses contaminants can dissolve in the tank with the result of changing the EC and pH level. Before using, the clay balls must first be cleaned and stabilised properly.

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Clay pebbles with a stable Ph level of 5.5

Cleaning the clay pebbles is easily done. Simply place them in a bucket, bath or any suitable watertight container, cover with water adjusted to pH 5.5 and soak for 24-48 hours, changing the water once a day to ensure a clean, pH-adjusted medium.
This simple procedure is of utmost importance; if not carried out, the resulting instability in EC and pH can drastically affect plant health and development.

Flood & drain cultivation systems

Flooding cultivation systems are composed of a large tray of about 10 cm depth, which we fill with the clay pebbles as if it were a planter. This tray has a drainage outlet connected a vertical overflow tube that works as a flooding-level control and empties the water if for some reason the pump doesn’t stop when it should. In this way we avoid nasty surprises and potential damages from overflowing irrigation water flooding the entire growing space.

The tray with the clay pebbles will also have an outflow for the evacuation of the nutrient solution, leaving the substrate moist but not waterlogged, enabling us control humidity and irrigate again when necessary.

In this growing system the method of watering differs slightly from the typical drip irrigation methods. In flood & drain systems, the total duration of the irrigation process between filling the tank and emptying it, shouldn’t last more than 20 minutes. The frequency of irrigation will vary according to the stage of development and condition of the plants. We can begin with two daily waterings and finish with five, or six at the end of the flowering stage, always taking into account the needs of the plants.

Before beginning cultivation with this system, we must previously plant the cuttings or seeds into rock-wool cubes. This ensures plants already have good root development enabling them to start growing with strength and vigour.

Flooding and ebb and flow culture system

Once we have the plants well-rooted in rock-wool, we place the cubes into the expanded clay. For optimum development, we should take care to ensure all the rock-wool is fully covered by the clay pebbles, avoiding exposure to light that can affect the roots.

Remember that it will be necessary to change the nutrient solution in the tank when we begin to flower the plants. Initially we are using a nutrient designed for vegetative growth and this won’t be suitable for our blooming plants. In addition, the EC level will vary according to which stage of life the plant is in. It’s possible to carry out maintenance of the nutrient solution so that when you observe a decrease in the EC or the water level, you will have to fill up with water adding nutrients until reaching the desired EC level and thus leaving the deposit ready for the following week.

Drip irrigation systems

If we grow in clay pebbles with drip irrigation systems, we should take care with the placement of the drippers to assure an even distribution of water within each pot. It is important that all areas of the substrate are receiving the same, or at least very similar levels of moisture. In this way we can avoid any dry pockets of growing media, given that the roots only are going to develop where moisture is present.

When deciding on a watering schedule, it is also important to take into account factors such as humidity. If the grow space has high levels of humidity and insufficient ventilation, the substrate will stay wet for longer. In consequence we have to provide fewer waterings which also should be more gradual. On the contrary if we see that the humidity is lower than usually and we have a constant air ventilation with fans, the residual humidity levels will be lower than normal. In this case the irrigation should be more frequent and of a longer duration.

In hydroponic growing systems like this, where the substrate offers little in the way of protection to the roots, it may be necessary to use an additive product, for example Mineral Magic from GHE which contains silica and helps us protect the plants from possible root rot, diseases, virus, etc.

As part of the ongoing maintenance programme, drip irrigation systems will require cleaning with a salt-remover like Pro XL Pro-Clean. In this way we avoid the buildup of residual salts in the tubes and drippers which could eventually lead to blockage and cause serious problems with our grow.

Cannabis plants grown in expanded clay

Fertilising plants grown in clay pebbles

Expanded clay is a highly oxygenated substrate in which the roots are attached-to and grow around the clay, growing in direct contact with the nutrient solution.

The EC levels in these growing systems should be lower than those normally used for growing in coco-coir. The EC level of the nutrient solution shouldn’t initially exceed 0.6 points and we will have to increase it as plants grow without exceeding 1-1.2 points during the growth period, provided we aren’t seeking extra growth for mother plants or establishing SCROG growing.

Once the root system is well formed and the plants have grown larger and more resistant than in their early stages, we can start to gradually increase the EC level to avoid deficiencies.

Upon entering the second week of flowering we can use an EC of 1.3-1.4 points. We should maintain these ranges up to the 4th week of flowering, at which point the flowers begin to increase in volume.

Cannabis grown in Aquafarm

In the weeks 5-6-7 we can give higher EC levels up to 1.5-1.6 points or more. We must always take the nutritional needs of our plants into account and adjust nutrient dose according to their life stage. During these weeks we will have to increase the frequency of watering to keep pace with the plant’s increased demand for nutrient solution. In this way we ensure that the plants receive the best nourishment possible to create large, tasty and resinous buds.

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During the last two weeks as we near harvest, we will need to switch the nutrient solution of the tank with pH adjusted water (6.2) mixed with a flushing product/root cleaner. This process will help the plants to get rid of the nutrients that are in their metabolism and wash away any mineral salts adhering to the root system, resulting in a better taste and smell to the flowers.

How to properly flush the roots of cannabis plants

In hydroponic systems using recirculating irrigation, we can use an auxiliary water deposit for the washing of roots. This way, we can avoid the need to empty the main tank in the case of over-fertilising, thus saving the fertilisers used in the composition of the nutrient solution. We should adapt the drainage of the auxiliary tank to avoid any accidental mixing of contents between both deposits (the auxiliary and the main one).

To thoroughly flush the roots, fill the auxiliary tank with water with a very low EC, as close as possible to 0.0 points. To the tank we then add an enzyme product and if we are at the end of flowering, we can also use a flushing product. This will help to flush all salts from the substrate and the roots, leaving them clean and allowing them to recover in a few days, evacuating the excess nutrients by reverse osmosis.

Cannabis plants grown in clay pebbles

In the case of over-fertilising, when the plants have rid themselves of the nutrient excess or when we observe a clear improvement in their condition, we may proceed to irrigate again with the nutrient solution in the main tank. Previously, we must adapt the EC level of the tank to the suit the phase of the plant’s life cycle. We should proceed by diluting the content of the tank with water that has an EC as low as possible with the purpose of lowering the final EC of the nutrient solution by a few points.

One point to consider when growing is that there can be great differences in nutrient requirements between different varieties of cannabis. For this reason, when cultivating hydroponically, it’s advisable to grow varieties with similar nutritional needs. However, it is possible to make a division of the tank and the irrigation system in order to use two deposit tanks with different nutrient solutions according to needs of the two varieties.

How to use Hydrogen Peroxide with clay pebbles

Hydrogen Peroxide or H2o2 is widely recognised as a great disinfectant. This product can be used as a preventative to disinfect the growing medium where our plants will grow. The expanded clay pellets may be contaminated and often contain elements that aren’t compatible with growing of cannabis. For this reason it is always appropriate to use H2o2 to disinfect the substrate. To disinfect fully at the beginning of the grow, we recommend running the system with H2O2 during at least 24 hours before we introduce the plants to the growing medium. This will leave the expanded clay substrate free from any impurities that could negatively affect our plants.
We can also use H2O2 to clean the roots of the crop after we change the photoperiod from growth to flowering. This will leave the roots free of salts and in great condition to start the flowering period with health and vigour. In the case of using fertilizers type A+B, this kind of root washing is not necessary. The dosage of hydrogen peroxide to use is 1:2000 or equal to 50ml per 100 litres of water.

The Ph level in hydroponic crops

EC and PH meter from Hanna

The PH level is an important factor when cultivating cannabis plants in any hydroponic system. This is due to the use of inert substrates, which are free from nutrient content and don’t have the same buffer effect that soil has. This means that the plant is only able to feed on the aqueous solution. A well regulated pH level acts somewhat like a stopcock, in that it regulates the feeding flow and controls the plant’s assimilation of nutrients.
For the growth period, the pH range can vary depending on the size and phase of the plant. For seedlings, plants and cuttings we can use a pH level of 5.5 to 5.8, while during the flowering period we employ a pH range that fluctuates from 6.0 to 6.2.
The pH fluctuations can be controlled within a logical range suitable for the uptake of nutrients. We can allow the initial pH of 6.0 to fluctuate up to 6.2 and later down to 6.0 again. In this way we will ensure that the plant is able to uptake all macro and micro nutrients within the nutrient solution and thus ensure an optimal development.

The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.

Understanding Deep Water Culture and Feeding

Deep water culture (DWC) is emerging as the hydroponic system of choice for cannabis growers because of its fast results and reduced labor. Follow Dan Vaillancourt’s guide to DWC to see if it’s the right method for you.

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Deep water culture (DWC) is a low maintenance, fast-growing method of hydroponics. In this type of system plants sit in net pots with roots suspended in the grow chambers nutrient solution while aerated water recirculates throughout the growing system.

If you have ever heard the phrase “look at your roots, not your fruits,” then you may understand why growing in this style of hydroponics can be very lucrative. When your plants’ roots have little to no resistance to push against, combined with proper temperature, oxygen, and nutrients, it’s easy to see the incredibly fast, lush growth above the root base that DWC is famous for.

Going Deep with Deep Water Culture

The reason it is called “deep” is because of the small air bubbles that travel up and through the water from your air stone at the bottom of the tank. As these air bubbles travel upward they spin, gathering more oxygen in this process and releasing it into your water, increasing your overall dissolved oxygen levels, making deeper water work better for this method.

Higher water volumes in your overall system will also result in less pH and fewer temperature and PPM fluctuations, making the deep aspect of this growing system and the combined grow chambers useful for a smaller fertigation room feed tank. Utilizing the grow chambers’ water volume allows you to have a small controller tank and a compact fertigation room depending on the number of plants you have.

In a deep water culture system plants sit in net pots with roots suspended in the grow chambers nutrient solution while aerated water recirculates throughout the growing system.

Fast Feeders in DWC

Deep water culture hydroponic systems have immediate access to all the nutrients they need at any given moment, making them easy to overfeed if it’s not done right.

Maintaining a low PPM of nutrient strength and only raising at peak flowering periods, coupled with regular flushing, is ideal with DWC because this will keep your plants from getting too many nutrients, which can cause problems.

If you notice tip burn, where the tips of the leaves turn slightly yellow, or burnt and crisp in later stages, then you have added too many nutrients. Prior to this, the plants will likely be a very deep green in color. Ideally you want the plants to be vibrant green, not too pale, and not too dark green.

Tip burn is only the visible sign of too much nitrogen. An excess of other nutrients will look different, depending on which nutrient is overabundant.

Ideal nutrient levels differ based on the strain, type of nutrients added, stage of growth, light intensity, and CO2 levels, so unfortunately there is no silver-bullet formula. But these variables dictate the optimum levels your nutrients and additives should be at each week throughout the growing stages.

DWC is Less Labor and Environmentally Friendlier

Water consumption, nutrients, and labor are all much lower with DWC. This is because a drain-to-waste system will waste the nutrients you feed them each day, whereas a DWC system recirculates the water and it is swapped out once weekly. This accounts for at least 90 percent savings in water and nutrients and cuts back drastically on labor needed in filling tanks and mixing nutrients regularly.

This growing method is a favorite for hydroponic gardeners in areas prone to power outages. In the case of an outage the growing system does not dry out or overfill. Instead, the recirculation and aeration will stop (along with the other equipment), however, oxygen remains in your solution for roughly 48 hours, which is generally within the time an outage will be fixed.

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Although this growing method is the safest in the event of a power loss, we still recommend exchanging the nutrient solution for a fresh one once power is back on. Cleanliness is very important in recirculating hydroponics methods.

Once a week, 29 percent hydrogen peroxide should be added to plain, pH-adjusted water and run through the system for 12-24 hours. This will clean your tanks, piping, and root base while adding oxygen to the roots. This should be applied at a rate of 3 milliliters per gallon.

Plants leaves will perk up during hydrogen peroxide flushes and flowers will swell due to the added oxygen making this tip both useful for a clean system and good growth.

Maximum Yield with Deep Water Culture

Licensed for a certain number of plants? Out of all the types of hydroponic systems, DWC is one of the best for utilizing your plant count and making the most of it with its ability for large, bushy growth. Filling large areas with very few plants is easy with DWC.

As amazing a system as DWC is, it is not right for every scenario. The large bush-style growth does mean you will have to keep them in the vegetative state for longer (two to four weeks), so a larger vegetative room is needed. Water chillers will also be required to maintain a correct water temperature due to the water passing through the warm growroom pipes.

If vegetative space is low, water or nutrient consumption is not of big concern. If you want to throw a grow system together faster, an automated stonewool or coconut husk drain-to-waste hydroponic system may be more up your alley.

Although DWC can cater to the low-plant-count grower and produce large bushes, it can also be designed closer together and focus on top flowers. Proper growroom design and fertigation planning is crucial to a successful deep water culture system.

There is no growing method quite like a fully automated DWC system. The level of control you have over your roots offers the healthiest, fastest growing plants possible. Hopefully this basic understanding of DWC will help you choose the best growing system for your needs.