Flowering Grow Lights, Stages and Tips | Dorm Grow (2024)

FAQs

How long should lights be on in flowering stage? ›

Rather than bogging down in botany, keep your growing simple by following three guidelines: use full-spectrum LED grow lights for all cycles, keep them on at least 18 hours during vegetative growth, and cut back to 12 on and 12 off for flowering. Then sit back and enjoy your harvest.

Red radiation (around 700nm) is considered most efficient at driving photosynthesis – especially in the flowering stage for biomass growth (important to Cannabis growers). Blue light is essential for both the vegetative and flowering stages of plant growth, but mainly for establishing vegetative and structural growth.

The ambient room temperature should be below 90 degrees Fahrenheit (ideally 82-85 degrees) and as low as 72 degrees when the lights are on. Temperatures will be lower during the off period when the lights are not in use.

Lower wattage LEDs of around 200 watts should sit between 12-20 inches from the top of the plant. Higher wattage LEDs of 1000 watts and above should sit between 36-46 inches from the top of the plant.

Generally, you want to water every 2 or 3 days during Flower and you want to water enough that 10-20% of water comes out from the pot as runoff. You can check your soil moisture by sticking a finger in the pot: if the soil is dry a couple inches down, then it is time to water again.

If plants have a short-day response, then shortening the days by totally excluding light from the plants for 12 hours per day will accelerate flowering.

During the flowering stage, you should decrease the DLI and increase the light intensity. The photoperiod should be 12 hours during the flowering stage.

A dimmed light won't provide the same exclusive spectral distribution and can change the quality of plant growth. It's understandable that some growers may want to dim their grow lights, but it's best to keep your lamps at full power.

When adding CO2 to your grow room, the flowering stage is the most important. Adding CO2 to your grow room, especially in the first 2-3 weeks of flowering, can kick start flower production and boost flower size significantly. Use Exhale CO2 bags to naturally provide your plants the extra CO2 they can thrive on.

Although some heat will always exist in the grow room, too much heat is a problem. In fact, high temperatures are one of the most common issues indoor growers have to deal with. Growers need to maintain the optimal grow room temperature to avoid the negative effects of high temperatures on plant health.

Should I run my grow lights at night or day? ›

A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It's believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.

Manipulate temperature and humidity

In the flowering stage, temperatures in 65- to 80-degree range are ideal. At night, most plants prefer temperatures between 68 and 75 degrees Fahrenheit. Colors like pink and purple come out when nighttime temperatures are at the low end of the scale.

Intense, direct light is great for some plants, but it will damage (or even kill others). The plant isn't able to convert all of the light into consumable energy, and the excess creates a heat issue over time. The plant might use available water to cool itself, which creates a moisture shortage as well.

Telltale Signs of Too Much Light

The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.

The LED grow lights should be between 12-24 inches from the top foliage of your marijuana canopy. Monitor the plants closely to make sure they have enough light and not too much, which can cause adverse effects such as bleaching, discoloration, stunted or irregular growth.

You can remove fan leaves during flowering in much the same way you do during veg. Prune away large leaves that are overshadowing bud sites, as well as dead or dying fan leaves. One thing to keep in mind is that you should prune in intervals, giving at least a couple weeks between each session.

In week 2 of flowering, you may spot the first white pistils growing on your female cannabis plants. These fine and wispy white hairs will develop at those locations where the big fan leaves meet the main stem. It is these fine hairs that will later become buds.

We all grow up knowing plants need soil, sunlight and water, but we often don't realize the importance of consistently watering flowers. A lack of moisture can cause a flower garden to wilt and produce very few – if any – blooms. Overwatering flowers can cause disease and the drowning of plants.

The flowering stage occurs naturally when plants receive less than 12 hours of light a day. For cannabis to completely enter the flowering stage it requires periods of 10 to 12 hours of complete darkness.

How long is the average flowering stage? ›

How long does the flowering stage take? The duration of the flowering stage varies among different strains. The flowering stage in Cannabis plants usually goes from 8 to 11 weeks, depending on the strain. It's usually divided into weeks or three stages.

Get enough light – High-intensity lighting is one of the primary reasons that hydroponics growers can produce such big yields compared to traditional gardening. Because light is just as important as food to your plants, you want to make sure you're using the strongest, brightest lights possible.

Light burn may also cause loose and airy buds. That's because the excess light causes nutrient deficiencies as plants struggle to overcome their heat and thirst. Fortunately, you don't have to wait for these symptoms to emerge to know whether greenhouse lighting is too strong.

Flowering starts after more than 7 hours of dark period

Instead of splitting off leaves, the plant starts producing flowers. After two cycles of a sufficient enough dark period, the plant fully enters the generative phase.

Switching from Veg to Bloom

Plants need at least 13 hours of light each day to stay in veg – a few 'long' nights may be enough to trigger budding.

Blue light is vital for plant growth, and experienced growers recommend using blue light at various points in the grow cycle. Some growers recommend increasing blue light exposure – sometimes exclusively using blue lights – at the end of the flower cycle.

Faster flowering can result in significant savings and better profitability for plant breeders. Various conditions can affect the flowering speed, but the quality of the light spectrum is probably the most important.

Light intensity

To some degree, more light translates to fatter buds and higher yields (you'll need to pay attention to the distance between your grow light and plants or your plant may suffer from light burn). Increasing light intensity is the most effective way to fatten up buds.

Flowering – 5-20-5 or 5-25-10 – During flowering, you want to prioritize phosphorous to promote bud growth and make sure to limit nitrogen so your plant doesn't get too tall or “leggy.” You want it to concentrate on developing huge buds, not lots of stems or leaves, and phosphorus will make your buds grow.

There could be no best nutrients for flowering stage list without CANNA Boost. It is one of the most well known bloom boosters among growers, and for good reason. CANNA Boost contains calcium, magnesium and sulfur, plus additional micronutrients like chlorine, iron, zinc, copper and more to help boost nutrient uptake.

Do grow rooms need to be air tight? ›

The concept of a sealed room is quite basic; a sealed room is a growing environment where there are no holes or air exchanges to the outdoors or any other room. It doesn't need to be airtight, however, the closer to airtight the better.

While too much air movement can cause steam breakage, leaf tearing and growth in different directions, Quest's recommendation is you should always have a steady air flow in your grow up to that threshold.

Air in your grow area should be exchanged at least every 5 minutes. If you are using a grow tent that is 5' x 5' x 6' this is 150 sq/ft of air. For optimal airflow, you need a filter and fan that can move between 30 and 60 cubic feet per minute (CFM). It is also important to balance the flow in and out of air.

Sufficient lighting is essential for all stages of growth, but sometimes you can overdo it - leading to light stress in plants. This can cause a variety of issues with your plants. This can get tricky, because you absolutely need intense lighting to produce strong root systems to develop fruits and flowers.

Periods of darkness are required for plants as it affects their metabolism. It also gives them time to stop producing food (photosynthesis) and use the huge amount of energy they've stored through the day to grow.

With 24 hours a day of light, plants won't be able to access the energy stores it normally receives at night. Too much light can quickly lead to stress related-issues like vulnerability to disease, pests, or tissue damage.

More growth and stretching of the plants in Week 3

You will notice continued growth and stretching. You can see in the video how bushy everything has become. This rapid, almost non-stop growth is all a sign of the post-vegetative stretch that these plants go through after switching to the 12/12 light cycle.

The flowering stage is the final stage of growth for a cannabis plant. This is when plants start to develop resinous buds and your hard work will be realized. Most strains flower in 8-9 weeks, but some can take even longer, especially some sativas.

Ideal indoor relative humidity levels can range from 70% in the seedling stage to as low as 30% during the flowering stages. That's why it's important to deliver a wide range of indoor humidity throughout the growing process.

Once the vegetative stage is complete, plants enter the bloom or “flowering” stage. For established plants, they are already where they need to be in order to thrive. During the flowering stage LED Grow lights should be located between 16-36 inches from the plant canopy.

What light do plants grow worst in? ›

Green light is the least effective for plants because they are themselves green due to the pigment Chlorophyll. Different color light helps plants achieve different goals as well.

For a cultivation area or a grow tent of 80 x 80, you will need LED systems from 100W to 200W depending on the manufacturer. Any LED system between these watts will be enough to fully grow up to 4 plants.

As an unofficial rule of thumb, many growers work on the basis that: You need 20-40 watts of power per square foot. Lower wattage LEDs of around 200 watts should sit between 12-20 inches from the top of the plant. Higher wattage LEDs of 1000 watts and above should sit between 36-46 inches from the top of the plant.

If your pot doesn't have a drainage hole (which it probably should), you can also check on the root system by turning the pot over and very gently pulling the plant out. Overcrowded roots will have formed a thick web at the bottom of the soil in the shape of the pot.

Bud size may be increased through the following recommendations: Use an LED grow light with a spectrum that is best utilized by your plants. Place the LED fixture the correct distance from the canopy during the flowering stage. Create a footprint to deliver near equal amounts of light to all parts of the canopy.

For example, one single 300W LED light fixture may be fine for one or maybe two plants, but it may not be enough to cover a bigger space with multiple plants. So make sure to reference any recommendations from the vendor and/or LED manufacturer on how much light you will need for your growing space.

Once the light cycle is changed to 12 hours, adding more light to the plants helps increase the flowers and yield.

Most plants won't flower until they are experiencing an average of 12 hours of darkness. If the plants get more than 14 hours of light each day, you can keep them at this growth stage for a long time. The vegetative cycle also classifies into two major categories.

During the flowering stage, you should decrease the DLI and increase the light intensity. The photoperiod should be 12 hours during the flowering stage. And 18 hours during the vegetative stage.

How do I know if my plants are getting enough light? ›

When plants lack light, they don't produce chlorophyll (the green pigment in plants), and plants can turn pale green to yellow to white. Plant stems become “leggy,” meaning stems become long and thin and appear to be reaching toward the source of light.

12 or more hours of darkness is the biological trigger for photoperiod cannabis to bloom. Outdoors, as the nights grow longer incrementally from the summer solstice onward, some strains can even begin flowering when receiving 14 hours of sunlight.

With 24 hours a day of light, plants won't be able to access the energy stores it normally receives at night. Too much light can quickly lead to stress related-issues like vulnerability to disease, pests, or tissue damage.

When you grow indoors, flowering will begin once you switch your lights to 10-12 hours of darkness. For most cannabis strains, the flowering period will last about 7-9 weeks, although some sativas require even longer for their buds to mature.

Faster flowering can result in significant savings and better profitability for plant breeders. Various conditions can affect the flowering speed, but the quality of the light spectrum is probably the most important.

During flowering, switch the lighting schedule to 12 hours on and 12 hours off. The key for maximum yields is to provide large amounts of light and to distribute it as evenly as possible across the canopy. Space your lights accordingly.