One common theme I’ve noticed among indoor growers is that many use separate grow areas for different stages of growth. That includes using one grow light specifically for the seedling and vegetative (veg) growth phases, which includes mother plants.
Keep reading below to determine which one may best suit your specific needs.
Why A Strong Grow Light Is Important for Vegetative Cannabis Growth:
The vegetative phase of growth is so critically important for your cannabis plant’s future yields. This is the phase where the plant develops its physical structure. Some people choose to run weaker powered T5s or T8 lights during this phase. Weaker light leads to stretchy plants.
Take a look at the lights below that will provide sufficient intensity for maximum growth and development during this phase.
The Best Light Spectrum Temperature for Vegetative Phase Growth:
Any grow light with a white 4000K or 3500K spectrum will get you through the seedling and vegetative phases of growth. You can also choose a kelvin temperature above 4000K if you want.
I don’t recommend a kelvin temperature below 3000K for seedlings or veg because this color temperature is heavy on red wavelengths which is better for flowering.
If you want a dedicated seedling, vegetative phase, or mother plant grow light, the models I list below would be very good choices based on their specifications.
Another situation where you’d want one of these heavy blue spectrum grow lights is if you’re maintaining a mother plant. A mother plant is a cannabis (or other fruit/vegetable yielding) plant that you want to save for the sake of preserving its genetic makeup and creating clones.
The HLG 300L B-Spec may look small, perhaps for a 2×4 foot grow area. But the LEDs on the HLG 300L B-Spec are actually strong enough to grow seedlings and mother plants in a 4×4 foot area.
The B-Spec version of the HLG 300L model pictured above has a spectrum and LEDs specially geared towards plant growth in the vegetative phase. In other words this is a full blue/white spectrum grow light for seedlings and mother plants.
Take a look at the HLG 300L B-Spec spectrum below:
This seedling grow light utilizes Samsung’s LM301H 3500K white spectrum, plus 470nm blue LEDs. Out of all the LED grow lights I’ve seen, the HLG 300L B-Spec is the most dedicated seedling and veg spectrum available.
The HLG 300L B-Spec pulls 270 watts from your outlet when running at full capacity. If you desire, you can dim it down to 90 watts, or 33% power.
Larger Model for Larger Spaces:
Need to light an even larger grow space? Consider the larger HLG 550 B-Spec which has the same spectrum, but covers 6×6 feet.
Sure there are small grow light bulbs and tubes available for seedlings and veg phase as well (click here if you want to see those), but the light strength & spectrum quality doesn’t compare in a head to head comparison.
In addition, you’ll need several of those units to cover the 4×4 foot space you get from the HLG 300L B-Spec.
This is the HLG 260 watt B-Spec DIY kit. If you have 20 extra minutes to do an easy assembly, you can veg 4×4 feet of space and save $100 over the HLG 300L mentioned above!
Don’t be scared by the word DIY – there’s no soldering required! Only a screwdriver and wire strippers (or scissors). One person described the light as “fun and easy to put together,” in addition to saying they’re very happy with this vegetative phase grow light.
This HLG 260 watt B-Spec grow light is manufactured specifically for vegetative growth, with a 3500 kelvin spectrum plus 470nm blue LED diodes.
You can see in the spectrum image above that there’s little or no red spectrum, so you won’t be able to use this grow light for flowering.
The grow light is dimmable as well. All you need is a screwdriver to adjust the dimmer located under the rubber plug on the driver.
Last, this grow light comes with a one year warranty. As a DIY kit the manufacturer can’t warranty as long as pre-assembled grow lights, but HLG is a quality brand that I haven’t heard of any reliability issues from.
Click here to see more details and pricing for the HLG 260w B-Spec Grow Light at LED Grow Lights Depot
Budget Choice: Metal Halide Grow Light
This 400 watt iPower metal halide grow light kit will give you the power and the blue vegetative spectrum you need at an affordable price. It even includes a separate HPS bulb to use during flowering if you want.
The wing reflector will ensure the light is spread evenly across your grow space. You can light a 3×3 foot to 4×4 foot area for vegetative growth with one of these affordable grow light kits.
From looking at the spectrum chart you can see it has a high amount of blue, yellow, green, orange, and not much red. This light spectrum was specifically designed for vegetative growth.
As with any grow light, you will need ventilation in your grow space to keep the area cool while using this grow light.
|iPower 400w MH/HPS grow light:|
|Ballast:||400 watt, dimmable!|
|Dimensions:||21″ x 17″ x 6″|
|Coverage:||3×3 to 4×4 feet veg coverage|
|Where to buy:|
Why I advise against tube grow lights (T5/T8) for seedlings and mother plants:
When comparing to LEDs, the spectrum is not as complete, and the light intensity is sub-par. When you read about light intensity required during the seedling and vegetative phase of growth, and then look at how strong the tube grow lights are, they seem a bit weak and probably don’t give the best possible results.
What is the vegetative phase (veg)?
The vegetative phase (often called “veg”), is the phase of plant growth between seedling and flowering. This is when the plant forms, and your grow light and light spectrum play a crucial role in the plant’s development during this phase.
It’s this phase that the plant develops roots, stem and node spacing,
Most growers prefer their plants to be short and bushy, and the best way to ensure that is by providing your plants enough of the essential blue spectrum they require during the vegetative phase.
Why blue light spectrum is best for the seedling and vegetative growth phase, or maintaining mother cannabis plants:
If you haven’t figured out from reading yet, the blue light spectrum is the best for several plant developments like chlorophyll and chloroplast development, enzyme synthesis, and plant density. It also regulates responses to biotic environmental stresses.¹
Blue light and UV-A wavelengths also trigger cryptochrome and phototropin, which regulate chloroplast relocation, germination, elongation, and stomatal opening, which impacts water transpiration and CO2 exchange.²
In short, the formation of your plant and it’s ability to carry out certain functions in the flowering phase are directly affected by the quality of life it gets in the vegetative phase.
Why pick these grow lights for veg compared to other grow lights for both phases of growth?
When you compare a dedicated veg grow light to a multi-phase grow light, you’ll find that not surprisingly, the multi-phase light has less blue light intensity. That’s because those lights need room for LEDs that emit both blue, and red, and sometimes more.
If you’re looking to grow the best harvest possible, in addition to other factors, I strongly suggest considering a dedicated veg light. If you’re looking for a grow light for your mother plant, you’ll only need one with a blue spectrum, in which case a dedicated blue spectrum light would also be appropriate.
Why do growers want grow lights specifically for the seedling and vegetative phase (veg)?
Growers may decide to buy a dedicated grow light for the seedling and vegetative phases if their current grow light doesn’t emit enough blue spectrum – the spectrum that’s critical to the vegetative phase.
If you’re maintaining a mother plant you’ll only need a blue spectrum, and you’ll need a light that’s emits a blue spectrum that’s intense enough for a full sized mother plant. Having a light dedicated for this purpose is a smart choice.
The different aspect of the seedling and vegetative growth phases that requires an adjusted growing method are these two simple factors:
- The different light wavelength absorbed in this phase (we already discussed that)
- The increased sensitivity to light during these growth phases – which requires hanging your grow light higher than you would during flowering phase. This is why many of these seedling & vegetative phase grow lights emit lower PPFD readings. It’s because if you put too much PPFD on plants in these growth phases, you’ll risk burning them.
How Far Should Seedlings and Veg Phase Plants Be From Grow Lights?
Generally speaking, grow light manufacturers recommend hanging your grow light 24-30 inches above seedlings. But every grow light is different, so I advise reading my grow light hang height article, and following the steps for yourself to determine exactly how strong your grow light is, and how high you should hang it.
For the Vegetative growth phase you can get a bit closer, so hanging your grow light 18-24 inches from the canopy is more appropriate for this growth phase.
In reality it’s not the height that matters, you’re simply adjusting the intensity of light on your canopy by raising or lowering your light. So the logical solution to fix your problem is to determine the grow light height where your plants receive the ideal amount of light intensity for that phase of growth: 200-250 micromoles for seedlings and 300 to 400 micromoles of PPFD for vegetative phase plants.
I tend to say grow light hanging height is not a perfect science. You may find your plants react better if your lights are a few inches closer or further than manufacturers’ recommendations. The good news is if you find your plants start to get burned leaves from being too close, it’s a totally recoverable event, unless you let it go on too long. So check up on them regularly when you’re just starting out.
What’s the best grow light for a mother plant?
The best grow light for a mother plant has a strong blue spectrum with a coverage area large enough for the whole plant.
What light spectrum is best for the vegetative phase?
Blue spectrum is absorbed by plants during the vegetative phase and used to develop the plant’s structure, and prepare it for flowering.
What height to hang grow lights for seedlings?
Most grow light manufacturers recommend 24-30 inches for seedlings.
What height to hang grow lights during the vegetative phase?
For the grow lights mentioned above, 18 inches. In terms of intensity, you’d want a level where light intensity is 300-400 uMols.
What’s the best grow light for a very large vegetative grow space?
The Scynce LED Raging Kush will cover a 5 by 5 foot grow space for the vegetative phase with its fully customizable spectrum.
Is a grow light with majority blue spectrum only good for the vegetative phase?
Yes. You need balanced blue and red light for the flowering phase.