Reeferman Genetics – Chapter 11 – Grow Top Shelf Buds

This is where your big yield of high quality buds begins. Do not underestimate the difference a strong early start can have for the final outcome of your growing efforts, even if the harvest may seem very far away from your start date.

At this point, you have everything built following the suggestions in this guide and are able to maintain the growing environment set points we have recommended. Starting plants before your build is complete can lead to problems, especially if you underestimate how long and how much money it will take to finish.

The sooner you acknowledge that the plants are the boss in your growing efforts, the sooner you will thrive in the way of nice harvests and healthy growth. Plants won’t wait for you to finish. If they need more space or light and it’s not available things can start to go downhill very quickly, so plan for success, things will grow fast!

Preparing the Growing Medium

Two inch rockwool cubes or sheets of rockwool plugs (AO36/40) are a good choice for starting seeds or rooting cuttings from your mother plant seed selections. Oasis foam is also great for starting seeds and rooting cuttings. The main differences between the two media are that rockwool is more alkaline and Oasis holds more air–so the way to pretreat them differs. Pretreating conditions the media before you plant, it’s an important step that must be followed.

Pretreating Rockwool

This requires a soaking period of at least 18 hours, so plant around that. You also don’t want to leave rockwool soaking for more than a day or day and a half or there is the risk of funk from stagnant sitting water. Rockwool is very alkaline (high pH), so it needs to be presoaked in a mildly acidic solution with nutrients to buffer the pH and nutrient levels before planting. The process also helps to remove some of the finer particles or slag from manufacturing.

The rockwool will need to be completely submerged, so find a clean plastic container of suitable size, i.e., plastic pails or Rubbermaid type totes. A 5-gallon plastic pail is usually fine for smaller quantities of rockwool, i.e., a couple of ten by twenty-inch nursery flats worth.

Steps to follow

Step One-Fill the pail or tote with fresh clean water (RO filtered or dechlorinated is best) to a level that will be enough to completely submerge the amount of rockwool you intend to treat.

Step Two-Add nutrients following your chosen hydroponic feeding program recommendations for cuttings or seedlings. The overall strength shouldn’t be more than 1.0 EC, with 0.5 EC being a good place to start in most situations.

Step Three-Measure the pH and begin to add small quantities of pH Down (phosphoric acid or nitric acid). The desired value is around pH 5.0 for pretreating rockwool. The rockwool will raise this back up to pH 6.0 or so after about 24 hours of soaking. It can take a while to get the hang of adjusting the pH. ADJUST pH LEVELS GRADUALLY, ADDING SMALL AMOUNTS. DON’T OVERSHOOT YOUR TARGET AND START ADDING pH UP TO COMPENSATE.

Add Propagation cubes or sheets

Step Four-Gently add your propagation cubes or sheets. Just let them soak and sink, don’t force them to the bottom. Handle rockwool gently, you don’t want to compact the structure or roots will not have as much air space available to them. NOTE: wear a mask, long sleeves, and gloves when handling dry rockwool, it can be an irritant. It’s fine to handle once soaked.

Step Five-After 18 to 24 hours the rockwool should be sufficiently buffered and ready to plant. Gently (rockwool will be heavy now) remove the cubes or sheets and place them on a clean surface that allows them to drain freely. When rockwool is fully saturated it holds a LOT of water–too much in fact, let some drain away before planting. Optionally, you can flush and drain the pretreated rockwool on your clean surface with fresh nutrient solution adjusted to pH 5.5 (previously 5.0). This extra step freshens up the nutrient solution in the rockwool and washes away any remaining loose particles. The rockwool is now ready to plant, provided it is room temperature.

Preparing Propagation Trays

“Ten twenty” nursery flats are aptly named because they do in fact measure ten inches by twenty inches. Sometimes they are referred to as “prop” trays as well. Clear plastic humidity domes are available that fit snugly over the trays, available in various heights with four inches or six inches tall being most common. The humidity domes help keep cuttings or germinating seeds from drying out. You can fit a lot of small plants in a single prop tray!

The trays and domes may be reused until they start to crack or otherwise deteriorate, they are relatively inexpensive, so many growers only use them once or twice before replacing.

All of your propagation materials must be clean and sterile before starting. The warm and moist climate maintained for healthy young plants is also susceptible to growing all kinds of funk that can infect and devastate your young plants, especially in a closed humidity dome where there is little to no air exchange.


It is VERY IMPORTANT that you clean and sterilize propagation trays and humidity domes before use. Cleaning with isopropyl alcohol (rubbing alcohol) is very effective, using a sprayer bottle makes it even easier. Alternatively, one part chlorine bleach to ten parts water is also good for cleaning and sterilizing propagation materials, however, it will require lots more rinsing with fresh clean water before use, bleach residues may harm young plants.

Clean all other surfaces and equipment in your propagation area that will come into contact with plants the same as for propagation trays and humidity domes.

Other Recommendations for Your Propagation Area:

-Full spectrum fluorescent lighting (one or two tubes per propagation tray, six inches above propagation domes). Lighting can be on for 24/7 or 18/6 TIP steady temperatures are more critical than lighting in early stages; plants just need to know it’s long days out
-Very sharp scissors or scalpel or razor blades
-Measuring spoons or small measuring beaker or graduated cylinder
-Spray bottle
-Plastic cutting board
-Small plastic watering can
-Hydrometer (to measure humidity)
-Clean “poker” i.e., clean screw or nail that’s the right diameter for seeds or plant cutting stems
-Plant heating mat and control (optional)
-Nitrile or Latex gloves
-Root stimulator (rooting hormone)
-Permanent marker
-Plastic plant tags

See ENVIRONMENTAL RECOMMENDATIONS in Grow Room Environmental Control Chapter for optimal results.

Planting Seeds, Germination

Your growing medium (rockwool or Oasis) following pretreatment method, trays, and other equipment should be ready and operational before planting seeds. Planting seeds is easy, easier than taking and rooting cuttings.

If your rockwool or Oasis doesn’t already have a hole poked, using your clean and sterile poker push a small hole about one quarter to one half inch into the germination medium. Using clean hands or preferably nitrile or latex gloves, gently push a high quality seed into each of the holes. They should be around twice the depth of the size of the seed. Once planted, gently “pinch” the top of the rockwool or Oasis so the seed is covered and has good contact all around with the germination medium. Cover the tray with your clean humidity dome. That’s it!


High quality cannabis seeds may take anywhere from a few days to up to two weeks before all seeds have germinated. Faster isn’t always better. You won’t know which ones are your best plants until harvest.

Check on the seedling tray daily. A covered tray typically won’t need any additional watering. Watch that the temperature is a steady 75-to-85-degree Fahrenheit and humidity is above 85% inside the dome. If it stays cooler, you can try positioning the light closer to the top of the tray or use a propagation heat mat and control (waterproof gentle heat mat under the tray with a thermostat control).


Once half or more of the seeds have emerged, remove the humidity dome, or open the vents on the lid all the way. Excessive humidity once seeds sprout will make your seedlings s-t-r-e-t-c-h with undesirable soft and weak growth. You want to build strong tight plants from the early stages for the best harvest possible.

Do not expose the young seedlings to very strong light or air movement, they will dry out quickly and die or become severely stressed. Follow the environmental recommendations given in the Environmental Control chapter of this guide through all growing phases. Once seedlings have their first set of “true” leaves they are ready for very mild fertilizer, otherwise pH adjusted clean and filtered water is fine.

Nutrients & Fertilizers

Oasis plugs may require daily watering once the lids are removed. Rockwool may not require watering for days. Follow the nutrient recommendations given in the Nutrients & Fertilizers chapter of this book carefully for best results.

TIP: get to know the “feel” and color of your growing medium when it is wet and when it is dry.

After rockwool or Oasis has dried about 50% from last watering, it’s usually safe to water or fertigate again. Don’t suffocate tender young roots or cause stem rot with excessive watering in young plants. Don’t leave freestanding water in the bottom of the trays (a plastic syringe or turkey baster can help you get it out without disturbing young plants).

After the seedlings have several new sets of leaves, they will be ready for transplant or preveg.

Taking & Rooting Cuttings

Your growing medium (rockwool or Oasis) following the pretreatment method, trays, and other equipment should be ready and operational before taking cuttings.

If your rockwool or Oasis doesn’t already have a hole poked, using your clean and sterile poker push a small hole that is a little smaller than the thickness of the plant stem you will cut down to a depth of about one-half inch to one inch. Don’t push the hole right through to the bottom. You want to leave some media below the cut stem and the bottom of the rooting medium.

Fill a clean plastic jug or glass with some fresh, clean filtered water and using a very sharp pair of scissors, razor or scalpel that is sterile, remove some branches from your mother plants. The lengths should be longer than the final cutting size you desire, as you will cut these once more before sticking into the rooting medium. Leave some nodes on the mother plant for new growth. It is advised that you don’t cut off more than thirty percent of the mother plant’s original mass. Note, we’ll talk about mother plants more later on. Make sure the cut ends are completely submerged.

Gather Donor Material

Once you have enough stem material with healthy foliage in your jug or glass, place it beside your tray full of prepared growing medium and a clean and sterile plastic cutting board. It’s best you don’t perform taking cuttings in strong air movement from fans. Cuttings are quick to go limp and suffer;. Speed and a still environment are important for healthy cuttings that are fast to root.

Cut and Stick

On the clean cutting surface with your prepared tray of rooting medium within arm’s reach remove a cut stem from the jug (only do one at a time). The final desired length of your cutting is usually from four to six inches. Remove excess foliage at the growing point. You should just have a crown of foliage around three inches in diameter. Trim excess leaves off and even trim the leaves that remain to be shorter. Imagine a little cocktail umbrella! Now making a diagonal cut, cut the bottom part of the stem off to the final length. It’s ideal if the cut can be made on a node. IMMEDIATELY dip the cut end to about half inch depth into your root stimulator (in a shot glass, poured out of the original container to avoid contamination). IMMEDIATELY stick cut end firmly into the rooting medium.

Repeat this process until you have the desired number of cuttings. If you have a lot of cuttings to take, you may mist the cut stems with fresh clean filtered water lightly. This will help keep them hydrated until they can be covered with your propagation dome. It’s best if you can avoid misting them, work quickly.

Cover Securely

Cover securely with the humidity dome once you are done and place under your propagation lights.

Check on the cuttings tray daily. A covered tray typically won’t need any additional watering. Watch that the temperature is a steady 75-to-85-degree Fahrenheit and humidity is above 85% inside the dome. If it stays cooler, you can try positioning the light closer to the top of the tray or use a propagation heat mat and control (waterproof gentle heat mat under the tray with a thermostat control).

Hardening Cuttings

If the humidity dome has adjustable vents, keep them open for about 5 to 10 minutes daily. Otherwise carefully lift the lid off for a minute and remember to put back on right away. Don’t lift the lid off if there is air movement; unrooted cuttings will dehydrate quickly.

In seven to fourteen days, you should see roots emerging from the bottom of your propagation medium. Once you see that most of the cuttings have roots emerging, start leaving the humidity dome open for longer periods. After cuttings are well rooted they will be ready for transplant or pre-veg. This usually is after two weeks from taking the original cuts.

Transplant & Pre-Veg

At this stage your cuttings should be well rooted, and seedlings should have healthy new true leaves and some root mass to match.

Prepare a sufficient amount of loose absorbent rockwool flock following the pre-treatment given above in propagation. A pint sized container, like a beer cup with drainage holes or aeration cell trays are what each of the young plants will get potted up into using the pretreated rockwool flock. You can usually squeeze fifteen to eighteen beer cups in a standard 1020 nursery flat. Alternatively, you may choose rockwool cubes.

TIP: Handle hydrated and pretreated rockwool flock GENTLY when filling containers. You want it loose for good air and drainage. DO NOT COMPACT LOOSE ROCKWOOL IN CONTAINERS.

Put a small amount of the wet rockwool flock into the bottom of the containers or pots. If you used wrapped rockwool cubes to start seedlings or cuttings, cut the wrapper off now. Gently place into the container with rockwool on the bottom. VERY GENTLY place loose rockwool around the propagation plug or min cube until it is completely covered, to the top of the transplant container. Gently shake away excess moisture from the bottom of the container and place into a 1020 tray. Repeat until you have the desired number of transplants.

TIP: If your plant counts allow, start more plants than you intend to finish. Each step of the way in this process, leave a few less desirable plants behind. This way you pick only the best to finish from an originally larger number of plants. Don’t waste time and resources on the runts if you can help it. This is nature’s way; she makes more than she needs and eliminates the weaker ones.

Rooted Cuttings

In the case of rooted cuttings that you just transplanted up, put the dome back on, but do not secure it firmly to the lower tray. Over the next few days gradually increase the gap between the dome and the tray bottom. Your cuttings used to high humidity levels will not react well to a sudden change, especially if the air is drier or there is an increase in air movement.

Finally, take the dome right off and check back frequently to make sure the rooted cuttings are holding their own without the nursery dome protecting them any longer.

For each step of the way, you want to make the transitions as seamless as possible in your crop. Uninterrupted growth rates with no hiccups wins the race. Push too far and too fast and you will set the crop back or even ruin it. Plants started from seed following this guide will already be used to the environment outside of the nursery dome. They will be ready to move onto the next step in two to three days from transplant.

Increase Lighting Intensity & Air Movement, following the values given in Lighting and Environmental Control chapters

After five to ten days under stronger light and increased air movement there should be lots of new roots in the rockwool flock filled containers. Following the recommendations given in the Nutrients & Fertilizer Chapter, irrigate as necessary. Typically, once the containers have dried out fifty percent of their weight when fully soaked is an ideal time to fertigate. Let them dry out more than you might want to. A healthy established plant will send out lots of new root growth looking for water and minerals. Keeping the flock too wet hurts growth and development.

If plants are growing new leaves and there is a good number of healthy roots in the containers, it’s time to pot up into the next stage for veg. Remember, we are training champions,. One step at a time. Don’t rush to the next step unless the plants are ready.

Transplant & Veg

Pre-treat enough rockwool flock to fill the number of one-gallon pots you intend to pot with your best and most robust transplants. As a rule of thumb, use about thirty percent drier rockwool flock by volume. Once soaked and pre-treated it will compact a bit no matter how carefully you handle it.

Dip for Pest Control

This is a good time to dip the green part of your transplants, while still in small pots, into a mix of diluted insecticidal soap and potassium bicarbonate. This is a preventative treatment for common pests and powdery mildew. SEE Pest Control Section for more detail. Making a collar to cover the growing medium will help keep excess run off from the dip from getting into the root system or growing medium.

Remove the lowest set of leaves and branches, so there is space between the top of the growing medium and the plant foliage. This eliminates “the bridge to problems”, i.e., moist growing medium contacting upper parts of plant. It also helps to improve air circulation when plants are growing close together.


Following the method used for transplanting your starters into small pots,. Fill the bottom of your one gallon mesh bottom nursery pots with loose pretreated absorbent rockwool flock. Gently slide your transplant out of the small pot (cup the top with your hand to help keep the root ball intact) and place into the one-gallon pot. Gently drop pretreated rockwool around the root ball and fill to the top. Be extra careful not to compact the rockwool flock, use gravity, just drop it in around and over the root ball! Gently shake any excess moisture out of the freshly transplanted one gallon pot.

It is advisable to loosely cover the top of the one gallon pot with a sheet of opaque plastic (cut to shape) or cover with a few handfuls of grow rocks. Otherwise, it’s likely that unsightly algae growth will develop on top of the moist rockwool over time.

Veg Phase

Now the one gallon pots are ready to move onto the next phase, VEG, following the recommendations given in Lighting, Environmental Control, Nutrients & Fertilizer and Hydroponic System Set Up.

The majority of strains will not need to spend more than a week in veg growing hydroponically in rockwool to gain enough stature for a heavy yielding plant at harvest. Healthy hydroponic cannabis plants are capable of tremendous growth rates compared to their soil grown counterparts. Once you see healthy white roots growing out of the bottom of the one gallon mesh pots, they are ready for moving into the flowering tables in your bloom room.

TIP: Some strains respond well to “topping” and LST (low stress training). Both methods are intended to encourage lateral growth, i.e., a “bushy” plant versus the classic Christmas Tree cannabis plant profile. This should only be done in veg stage. It is not advisable to top plants at least four days before moving into the flowering room or initiating the bloom phase.


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