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Germanating marijuana seeds under led vs t5

How to Transition Cannabis from Prop to Veg With LEDs

Your carefully propagated young cannabis plants are rooted in the propagation area and ready to move to the vegetation room. Make the move stress-free for these young plants by gradually transitioning the light intensity from propagation to vegetative levels while minimizing environmental changes.

If your LEDs are integrated with a lighting control software like smartPAR™, you can program your lights to increase intensity incrementally until you reach your maximum vegetative light intensity.

STEP 1: Transition to LED Spectrum

If you’re switching from a LED propagation environment to a LED veg environment, you won’t need to worry as much about this step.

If you grow young plants under T5 fluorescent or metal halide lights in propagation, the first step in the transition to the vegetative phase is to acclimate your plants to the enriched spectrum of LEDs. This is a relatively quick process, taking only one to two days. During this step, match the light intensity of your LEDs in your vegetative rooms with that of the propagation room. This step is only to transition to the new spectrum. All other environmental variables remain the same.

Average light intensity for cannabis propagation is between 100-200 μmol·m −2 ·s −1 .

If you don’t know your propagation area’s light intensity, you’ll need to take light measurements for this step.

To measure light intensity, use a quantum-sensor light meter.

Quantum-sensor light meters measure photosynthetic photon flux density (PPFD). This allows you to match the light intensity as the plants see it, rather than the visible light seen by humans.

Full-spectrum quantum-sensor light meters measure light differently than meters that measure lumens or footcandles. Light intensity measurements of lumens or footcandles will significantly understate PPFD intensity. This is because they measure the light intensity based on how humans perceive visible light.

With a quantum sensor, take a few intensity readings at canopy level and average the readings to establish the average PPFD in your propagation area.

STEP 2: Begin to Increase Light Intensity

After your plants have acclimated to the LED spectrum, you can begin gradually increasing light intensity by 50% every 1-2 days. This allows for a gradual but timely transition. If you are growing more sensitive cultivars, you can increase the light intensity as slowly as every 7 days. If you are growing hardier cultivars, you can increase light intensity more quickly to complete the transition faster.

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Each time you increase the light intensity, review the environmental settings and plants’ responses regularly. Gradually transition the other growing area conditions and settings to vegetative levels. If you spot anything of concern, slow down the transition period to minimize stress on your plants. Each transition period can be as long as 7 days.

STEP 3: Repeat Until Ideal Light Intensity Reached

Continue to increase your light intensity until you’ve reached the vegetative intensity level. The ideal light intensity for vegetative growth is 400-600 μmol·m −2 ·s −1 . Once your light intensity has reached the level you want for veg and your plants are happy, let them veg away!

See the next article in this series, “How to Transition Cannabis from Veg to Flower”, to prepare for the transition from the vegetative to flowering stages.

Different varieties of cannabis respond differently to lighting applications. To see the effects of varying spectral ratios on a variety’s growth development, adjust the spectral ratios once plants have successfully transitioned to the vegetative stage and then monitor their growth to identify from these spectral ratios.

To keep stretchy or elongated varieties compact, try a high blue ratio (70% Red: 30% Blue) throughout the vegetative stage.

To help compact varieties stretch to allow space for buds to develop between nodes, try a high red ratio with less than 10% Blue.

You can set up a Spectral Control Program to test these ratios with the smartPAR TM wireless control system.

Using T5 Grow Lights for Cannabis

A few years ago, growers usually only used fluorescent tube lighting as a supplemental light for cannabis plants, or for young seedlings and clones only.

In recent years, we’ve seen the creation of new high-light-output versions of fluorescent grow lights which can actually be used through the entire vegetative stage.

Some growers even use fluroescent grow lights such as the T5 successfully to flower their plants (if the plants are kept short/small enough through growth control methods).

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In general, I recommend changing to stronger grow lights like LEDs or HIDs for the flowering stage because they will usually give you double or more yields/watt of electricity. Unless you keep your plants very small, they will need more light to produce buds than a fluorescent light can usually produce. If you’re in a dire situation where your plants have grown too big and you can’t afford to get a different type of light, you can supplement your fluorescent tubes with additional light, for example you could supplement their light with a few CFL(compact fluorescent light) bulbs wherever you notice any “shadowy” areas. This is only a minor fix – the real fix is to grow very short plants or upgrade to a bigger light for the flowering stage.

Training plants to grow very short will produce the best yields with T5 grow lights

The biggest problem with fluorescent tubing is that the light that they give off is only useful for about a foot or so. That’s why they’re kept so close to your plants.

T5 grow lights should be kept as close as possible without burning your plants.

Any part of the plant that is further away then 1-2 feet from the fluorescent grow lights is not getting an optimum amount of light, especially in the flowering stage when plants need a lot of light to produce buds.

With the new high output lights such as the T5, fluorescent lights can be used until the plants are about 24 inches tall, which is just enough to grow a very short plant through to the flowering stage when you control your marijuana plant’s growth through the vegetative stage.

The great thing about fluorescent grow lights is that they don’t get very hot, and they can usually be kept 1-4 inches from the tops of the plants at all times without having to worry about burning your cannabis leaves or buds.

The other great thing about fluorescent lights is that they are usually relatively low powered and won’t make a huge mark on your electricity bill.

There are many different levels of fluorescent grow lights including the T5, the T8 and the T12. I strongly suggest sticking with the T5 style of fluorescent grow lights for cannabis because they give off the most amount of light for the size, and are specifically designed to be able to support taller plants up to 24 inches.

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If the temperature is under control they can be kept as close as an inch or two away.

For optimal results, for vegetative growth choose fluorescent light bulbs that are labeled either as “Cool White” or “Cool” colored (also labeled as “6500k” colored).

For flowering, choose bulbs that are “Warm White” or “Soft White” colored (usually labeled as “2500K” or “3000K”).

Example of a ScrOG (Screen of Green) Grow Under a T5. Using a screen can be an effective way to create a flat, table-top shape to take the best advantage of T5 grow lights

However, you can use either type of lights during either stage and still get good results. People also use “Daylight” (5000K) bulbs with success.

If possible, opt for bulbs labeled as “High Output” (HO). This ensures that you’re getting the most lumens (light) from your bulbs. But any T5 bulbs will work – hundreds of cannabis growers have the harvests to prove it!

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