Do Marijuana Seeds Need Sunlight

If done incorrectly, germinating cannabis seeds can be a struggle. Luckily, we're here to help! Check out 5 germination mistakes you need to avoid! When cannabis seedlings have grown their second or third set of serrated leaves they are usually hardy enough to flourish in direct sunlight. Learn when that is and how to do that now. How much light does a weed plant need? Discover the answers plus cannabis light schedule tips, how to choose the best lights, helpful FAQs, and more.

Top 5 Germination Mistakes To Avoid When Growing Weed

Germinating cannabis seeds is necessary in order to sprout seedlings that develop into mature, healthy cannabis plants. However, complications with light, humidity, heat, and more could result in cannabis seeds failing to sprout. Find out what to avoid to ensure successful germination.

Germination is where the magic begins. Cannabis seeds must first germinate in order to sprout and begin their journey as living, breathing plants. However, if the germination process is done incorrectly, or is thwarted by some other variable, seeds can fail to sprout, leaving you with useless, spent seeds instead. Here are the top five mistakes to avoid when germinating cannabis seeds.

GERMINATING BAD SEEDS

One of the most common reasons seeds fail to germinate is because they are simply duds. Typically, healthy cannabis seeds should look a specific way and be of a specific colour. Viable seeds will appear round, not flat, and should be a beige to dark brown colour with subtle tiger striping. Seeds that have been flattened or are pale in colour may have a tough time sprouting into healthy cannabis plants.

Seeds that have been improperly stored may also fail to germinate. These tiny packages of DNA prefer to be kept in a cool, dark place with moderate humidity. Exposing them to heat, light, or extreme humidity levels (both high and low) could result in seeds losing their viability. As long as you source your seeds from reputable seedbanks and store them appropriately, you shouldn’t have to worry about bad seeds ruining your chances of successful germination.

TOO MUCH LIGHT

Generally speaking, seeds require a dark environment in order to germinate. After all, in nature cannabis seeds find their home in the dark embrace of soil. It can be hard to determine exactly how much light is too much for your seeds; however, err on the side of caution and germinate out of direct light. There’s no need to use your grow lights until after germination has occurred.

It is also likely that the quality of your seeds will affect their ability to handle direct light. Seeds that are already having a tough time germinating will have an even worse time doing so if they are exposed to excess light.

TOO MUCH OR NOT ENOUGH WATER

The amount of water you supply your seeds during the germination process will also affect their ability to successfully germinate. Some growers attempt to germinate by “drowning” them in a glass of water. While this ensures they will not go thirsty, it can actually be more harmful than helpful.

Once they pop, seedlings are very delicate and must be watered carefully. When germinating, your medium should be damp, but not overly wet for best results. On the other hand, a dry environment is basically a death sentence for your seeds. They need a constant source of moisture to sprout, otherwise they’re good as duds.

TEMPERATURE PROBLEMS

Cannabis seeds require a specific temperature range in order to germinate. Regardless of the germination medium you are using (soil, paper towels, etc.), the temperature in the environment should consistently sit in the 26–28℃ range. Seeds need to be kept warm during the germination process. At no point during germination should seeds be exposed to temperatures below 20℃.

There are some techniques that can be used to ensure your seedlings remain in this temperature range. Some growers choose to use special warming mats that can be set to a specific temperature and placed underneath the seedling containers. Another strategy is to place a timed heater close to your seedlings to warm them up occasionally. Once your seeds have sprouted, they will be much more resilient to fluctuations in temperature.

GERMINATING IN SOIL

Many people choose to germinate their seeds using paper towels. However, others choose to do so directly in soil. Of course, germinating your seeds in soil isn’t inherently bad, but it can come with its own set of challenges, and is generally not recommended unless necessary.

For instance, the upper layer of soil can dry out within 48 hours, making it more difficult to give your seeds the right amount of water they need without overdoing it. Giving your soil too much water during germination could result in the seed rising up or dropping down further, inhibiting its viability. Moreover, seeds that are planted too deep in the soil could experience a host of complications. They could suffocate before coming into contact with enough oxygen, and be unable to access sufficient light to progress into the seedling stage of their life cycle.

Seeds may also be unable to germinate if the soil they are planted in contains contaminants. Mould and pests can easily kill a mature, healthy weed plant within just a matter of weeks. It should come as no surprise then that they could also prevent a small seed from germinating. If your soil contains traces of these contaminants, it is possible that your seed will never actually open and sprout. This also applies to fertilisers. Even small amounts of fertiliser in your soil can effectively kill your seed, making it completely useless.

See also  Single Marijuana Seeds

When can seedlings be put under lights or in the sun?

Not sure whether to grow your cannabis seeds in the sun or under lights? This article explains how much light you need, how to prevent your seedlings from falling over, and when to plant them outside.

“When can cannabis seedlings be put under lights or in the sun?” is a common and sensible question that is often asked by novice cannabis enthusiasts after germinating seeds indoors under lights.

For those who are growing indoors, cannabis seedlings may be put under lights as soon as they emerge from the soil or growing medium.

How much light for cannabis seedlings?

When using HID lighting (usually a metal halide lamp), young seedlings should be kept at least 50cm from the bulb.

With compact fluorescent lamps (usually 100w or more), a distance of around 15cm should be maintained between the top of the young seedlings and the bulb.

If using normal fluorescent tubes (18-36w), seedlings can be kept within a few centimetres of the light source.

Cannabis seedlings growing under lights should always be given a gentle breeze from an oscillating fan (a small household fan on the lowest setting is fine), as constant gentle movement will strengthen their stems significantly.

Are your cannabis seedlings falling over?

If cannabis seedlings grow tall and then fall over, this is almost always a result of growing in an environment with static air.

Seedlings intended for outdoor growing should be kept by a sunny window for the first week or two after emerging from the soil.

When they have grown their second or third set of serrated leaves (after the the round cotyledons that initially emerge from the seed) seedlings are usually hardy enough to flourish in direct sunlight.

When to plant your cannabis seedlings outside?

If outdoor temperatures are suitable, seedlings may be acclimatised to direct sunlight by giving them progressively longer daily exposure to outdoor conditions.

Starting with about three hours outside, at the sunniest time of day, seedlings can be given an extra hour of outside exposure each day, so that within about two weeks they can be left outdoors permanently.

Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.

How much light does a weed plant need?

How much light does a weed plant need? A difficult question for many new growers. Light is one of the vital elements of all life forms, including weed plants, so you must get it right for your plants to thrive.

Keep reading as we unpack everything you need to know about cannabis lighting, from picking the best lights to optimum schedules. Let’s get started.

How much light does a weed plant need?

How you use grow lights determines the success of your marijuana plants. Answering the question, how much light does a weed plant need is complex. There are four lighting basics to master for the best results.

  • Light intensity
  • Type of light and placement
  • Light spectrum
  • Light schedule

Outdoors, the sun showers your plants in natural light, but indoors you’re in control of the cannabis light cycle.

Let’s take a closer look at each factor to consider.

Light intensity

Higher light intensity is generally associated with better growth. If you continue to increase the intensity of light that a plant receives, what happens? You might over-saturate your cannabis, which causes burns. However, your crops also risk stretching and stunted growth if you dim the lights too much.

Two common ways to measure light intensity are:

  • Lumen — measures the light flow that a source emits. The higher the lumen, the brighter the light.
  • Lux — measures the light intensity that reaches a plant’s surface.
Measurements of intensity

Growers typically use lux to measure intensity in their cannabis light schedule since plants only use the light that reaches its surface.

Here’s a simple table showing the best lux levels for two essential life stages:

Life stage Minimum Good Maximum
Vegetative ~15,000 lux ~40,000 lux ~70,000 lux
Flowering ~35,000 lux ~60,000 lux ~85,000 lux

Choosing the right lights

Using specific marijuana grow lights for your weed allows you to maintain the plant’s health and progress to the next growing season.

The more plants you have, the more lights you’ll need for a successful marijuana light schedule. Average home growers use around one or two lights since most states permit no more than 12 plants.

To improve the growth and flowering of your plants, you may invest in an infrared grow light. It’s not necessary but works well with HID and LED lights.

Before you figure out how much light a weed plant needs, you must choose the right lights. HID (High-Intensity Discharge) lamps, such as MH and HPS bulbs, have a hood that reflects light.

See also  Where Do Marijuana Seeds Come From

Metal-halide lamps (MH) are ideal for the vegetative stage of the cannabis light schedule, while high-pressure sodium (HPS) lamps are perfect for flowering. Using both bulbs allows you to reap double the benefits.

Most HID lights display a particular hue compared to the best LED grow lights, which may show many colors. Using LED lights is a fairly new practice compared to traditional HID lamps. LEDs use lower wattage but provide the same quality light spectrum as HID’s.

Before starting your cannabis light schedule, pick the best lighting options for you. Here are some pros and cons of HID and LED bulbs to help you decide:

HID

Pro’s Con’s
Extremely bright, emitting up to 130,000 lumens Need extra equipment like an electronic ballast and reflector
Efficacy rates of 150 lumens per watt Emit an intense heat that may burn plants or spike room temperature
Relatively low maintenance Degrade over time needing routine replacement
Lower outright cost Power-hungry so higher electricity bills
Easy set up/beginner-friendly
Options for different marijuana lighting cycles

LED’s

Pro’s Con’s
Energy-efficient/saves money in the long run No industry standard for LED lights
Runs cooler than HID’s, so low risk of burn Cheap models on the market may give inferior results
Mostly plug and go, no extra equipment Potentially lower yields than HID
Streamlined—supports veg and flower phase
Can last up to ten years

Distance from plants

Distance from the light can make or break your plants. Too close, and there’s a risk of light burn on weed, too far, and they won’t get the light they need. The optimum distance during your marijuana light schedule depends on the type of light and growing space.

During the seedling phase of the cannabis light schedule, grow lights should be kept around 24–36 inches away. Keeping an adequate distance prevents the seeds from drying out.

For the vegetative stage, lights should be 12–24 inches away. This phase of the cannabis light cycle requires more light for photosynthesis, so keeping them closer helps.

The light times for growing weed increase when flowering, and they should be kept around 16–36 inches away.

Here’s a handy guide for recommended distance depending on light wattage:

Grow light wattage Closest distance Furthest distance
150W 5 inches 11 inches
250W 6 inches 13 inches
400W 8 inches 19 inches
600W 9 inches 25 inches
1000W 11 inches 31 inches

Light spectrum for cannabis

Did you know the color of the lights influences your plants’ development? Different tones display certain hues based on the length of their waves. These varying shades suit the diverse stages, including a particular light spectrum for vegetative growth or the flowering phase.

The light spectrum for cannabis is the wavelengths between 380-750 nm. The colors represent the light wavelength. For example, if a light has a 400 nm wavelength, it appears purple to the human eye.

Light spectrum for seedling weed

During the seedling phase of your cannabis light schedule, use low-intensity light. Aim for 4000 lux—15% red, 30% blue, and white light.

Once your seedlings sprout their first leaves, you can double the intensity. When you spot more than two sets of leaves, it’s time for the vegetative stage.

Light spectrum for vegetative growth

For the vegetative stage of your marijuana light schedule, the main goals are root growth and tight internodes, so blue light is best. This shade stops your plants from growing too fast and developing long internodes, which causes light-blocking during flowering.

What is the best color spectrum for vegetative growth? For best results, use 27000 lux—100% blue light and less than 60% red.

Best light spectrum for flowering

In the flowering phase of the cannabis light cycle, your plants need more photons, so turn up the lux to 107,500—100% red while maintaining blue light at a lower level.

Lighting schedule

Excessive light increases your electricity bill and burns your plants.

Having a cannabis light schedule gives your flora a break. In the dark, your plants produce hormones that help them form buds.

Light and dark work together like yin and yang to form healthy greenery. How much light does a weed plant need? The answer depends on what stage the herb is in. Here’s a handy guide for the ideal light cycle for weed in different growth stages:

How many weeks does this stage last Lighting schedule
Seedlings 1–2 weeks 24 hours
Vegetative 3–5 weeks 18 hours on/ 6 hours off
Flowering 7–10 weeks 12 hours on/ 12 hours off
Light cycle for seedling marijuana

Seedlings are babies—they need all the care and nourishment you can give. In this phase of the cannabis light schedule, feed them 24 hours of light. After 1–2 weeks, your seedlings will sprout leaves and be ready for vegetation.

Light cycle for vegetative weed

The vegetative phase is the stage where plants grow bigger and taller. They need long days and short nights. To prevent early flowering, ensure they get at least 13 hours of light in your marijuana light schedule. 18 light hours and 6 dark hours will encourage healthy and steady growth.

See also  Novelty Marijuana Seeds
Light cycle for flowering cannabis

In the flowering phase, weed plants start forming buds. If they don’t get at least 12 hours of darkness, they may revert to the vegetative phase. During this stage of the cannabis light schedule, you must ensure that plants get absolutely no light during the dark times.

Optimizing lighting for maximum yield and minimal cost

Powering the grow room brightness can pull copious amounts of energy and cost you money. There are some ways to ensure you use lighting properly without going bankrupt. Here are some techniques to maintain the marijuana lighting cycles efficiently:

  • Use lower wattage, LED, or energy-efficient bulbs

Energy-efficient bulbs tend to be pricey upfront but save you money in the long term. HID bulbs can use lots of power, whereas LEDs use less.

Reflective walls bounce light allowing you to make better use of your grow lights. To make walls reflective, you can use materials like mylar and plastic.

Nighttime tariffs are lower in many states, so you can save money by using grow room lights at night. Indoor growing gives you control of the cannabis light cycle, and using lights at night won’t make a difference. As long as you follow the cannabis light schedule, your plants will thrive.

Providing ventilation

Ventilation is just as important as marijuana lighting cycles, water, and nutrients. Adequate airflow helps maintain the proper humidity levels, temperature, and CO2 levels in the room.

The most efficient method is to have two ventilators opposite each other and the exhaust system on a different side of the room. This way, you’ll have a balanced atmosphere with stable humidity levels and temperature.

FAQ related to how much light does a weed plant need

To help you a little more, we’ve put together the most frequently asked questions on marijuana light schedules.

What types of bulbs are best during vegetative and flowering stages?

Metal-halide lamps (MH) are the best option for the vegetative stage, and high-pressure sodium (HPS) lamps are ideal for flowering. During different phases of the cannabis light schedule, bulb settings with different lux are used. Bulbs with lux 27,000 work for vegetative and lux 107,500 for flowering.

How many hours of light do marijuana plants need?

It depends on the stage that the plants are in. In the vegetative stage, they need 18 hours of light and 6 hours of darkness. During the flowering phase of the cannabis light cycle, weed plants need 12 hours of light and 12 hours of darkness.

Can you leave grow lights on 24 hours a day?

You can only leave grow lights on for 24 hours a day during the seedling stage. Seedlings need all the nurturing they can get, and more light helps them sprout faster. During this phase of the marijuana light schedule, low-intensity light helps seedlings grow.

How much sunlight does a weed plant need?

How much sunlight does a weed plant need? The more, the merrier. Cannabis plants need at least 10–12 hours of direct sunlight to thrive. They can still grow healthy with a minimum of 6 hours of daily sunlight, but you’ll get a smaller yield.

What is the best color spectrum for vegetative growth?

Blue light bulbs with 27,000 lux—100% blue light and less than 60% red are best during the vegetative stage. It works best because blue light produces chlorophyll—a chemical that helps plants grow stronger and move to the next stage.

If you continue to increase the intensity of light that a plant receives, what happens?

If you increase light gradually following the recommendations for the cannabis light schedule, then your plant will flourish. Increasing intensity outside of the guidelines can cause your weed to burn. Cannabis plants need the most intense light when flowering, and too much before that can be detrimental.

Key Takeaways

How much light does a weed plant need? Cannabis plants have different light needs depending on their stage. Seedlings need 24 hours, vegetative stage weed needs 18 hours, and flowering plants need 12 hours of light.
There are many factors to consider, such as color spectrum, light type, marijuana lighting cycles, and intensity. Remember, healthy plants start with quality seeds. Shop our selection at i49 of the finest weed seeds now.

  • Cannabis Consumption
    • Edibles & Recipes
    • Ways to Smoke Marijuana
    • Cannabis News
    • Germination & Seedling Stage
    • Time to Harvest
    • Vegetative & Flowering Stage
    • Climate Control
    • Indoors 101
    • Lighting Requirements
    • Your Grow Room
    • Climate and Weather
    • Outdoor Grow Calendars
    • Outdoors 101
    • Nutrients
    • Watering
    • Beginners Guides
    • Plant & Seed Types
    • Setting Up: Tools & Equipment
    • The Cannabis Plant
    • Hydroponic Growing
    • Optimizing Yields
    • Pruning Techniques
    • Sexing & Making Seeds
    • Animal and Insect Pests
    • Fungi & Other Diseases
    • Growing Issues
    • Nutrient Problems
    • CBD

    How to Identify a Female Marijuana Seed 15 March, 2020 How to Identify a Quality Marijuana Seed Ask any e. Read Article

    Hydrogen Peroxide and Cannabis 1 May, 2020 The Benefits of Hydrogen Peroxide in Hydroponics a. Read Article

    How to Speed Up Flowering of Outdoor Cannabis Plants 2 April, 2020 A good deal of cannabis horticulturists grow their. Read Article