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What temp to plant cannabis seeds outdoors

Cannabis temperature: know the ideal temperature for growth

So, you want to grow cannabis but aren’t too sure what the right temperature is for your weed plants to flourish.

Figuring out the ideal cannabis temperature for your particular strain is essential to a fruitful harvest.

In this article, you’ll discover all you need to know about controlling the temperature and what to do if it gets too hot or cold.

Why is the temperature important to grow cannabis?

Unfortunately, unlike animals, plants cannot create their own heat. A cannabis plant’s ability to grow and to its fullest potential heavily depends on the skill and expertise of the grower.

Temperature affects rates of cellular respiration, photosynthesis, and the prevalence of disease in cannabis—making it an essential aspect for the cultivator to control.

The effects of temperature on cannabis growth

The temperature for growing weed plays a significant role in cannabis growth. Let’s take a closer look.

Temperature and photosynthesis

Photosynthesis is positively affected by temperature until a certain point. Hotter than that, and the high temperatures begin to harm the plant. Lower temperatures, on the other hand, cause slower growth and a low yield.

Temperature and respiration

A higher marijuana growing temperature significantly increases cellular respiration, where it becomes more than the rate of photosynthesis. When temperatures lower, respiration decreases, and so does the rate of growth.

Temperature and disease

Like humans, cannabis plants are susceptible to disease—some diseases persevere better in warmer temps, while others in colder temperatures.

Growers more commonly encounter gray mold in cold climates with moisture. Root rot is more likely in summer, and pathogens like powdery mildew grow in humid conditions.

Best temperature ranges to grow weed

Manipulating the environment to the ideal temperature for growing weed is vital. Below you’ll find our best suggestions for the choice of temperature at the different stages of growth.

Clones and Seedlings The perfect cannabis seedling temperature is between 68–77°F/20–25°C.
Vegetative stage This stage is best done between 68–77°F/20–25°C.
Flowering stage The best temperature for flowering cannabis is between 68–77°F/20–25C°.
Late flowering Here you can lower the temperature a little bit to about 64–75°F/18–24C°.
Drying and curing The best temperature and humidity for drying cannabis should be at about 70°F/21C°, and humidity at 50%.
Curing should happen at around the same temperature but between 58 and 65% humidity.
Indica Indica strains do better in colder climates than other strains. Popular strains include Purple Kush, Northern Lights, and Blue Cheese.
Sativa Sativa strains normally do better in warmer environments. Good strains include Durban Poison, Lemon Haze, and Strawberry Cough.
Hybrid This depends on whether it’s indica or sativa-dominant. Indica-dominant strains do better in cold climates, while the reverse is true for sativa strains.
Marijuana users enjoy hybrid strains such as Blue Dream, OG Kush, and Pineapple Express.

What happens when the temperature is too hot?

Figuring out the right growing weed temperature isn’t easy. The heat will restrict plant growth if it’s too warm, and the cannabis leaves will begin to curl.

How do you fix the temperature?

There are several easy options to get the best temperature for weed.

You can opt to move your grow lights away from your plants. Alternatively, you could increase circulation by using a fan.

For outdoor plants, you should water them both in the morning and the evening. You may also want to introduce artificial shade should the heat become an issue.

Indoor marijuana grow tents are a great way to deal with temperature issues if you’re currently planting indoors.

What happens when the temperature is too cold?

If the marijuana growing temperature is too low, this can stunt growth or even kill your cannabis plant. Getting a marijuana growing calendar is an excellent idea as it shows you the average temperature per month and other helpful information.

How do you fix the temperature?

There are certain aspects out of your control.

If you live in a colder climate, buying marijuana strains that grow well in cold environments may be better. Indica strains should be your go-to for this.

Additionally, some plants do better indoors, so growing inside might be preferable to moderate temperature. Grow lights, heating mats, and space heaters are the privileges of the indoor cannabis grower.

How can you control your growing room temperature?

Maintaining the ideal marijuana growing temp is paramount to having an excellent harvest.

Here are a few things that you can do to control the cannabis temperature:

  • Account for the wattage of your lightning. Higher wattage bulbs put off more heat and pose a risk to your cannabis. Stay on top of temperature monitoring in this case.
  • Adjust your light schedule. Many growers keep their lights on all day. If you need to reduce the temperature, switch them off for a few hours a day.
  • Add CO2 to the air. It’ll make it so that your plants can survive higher temperatures and induce faster growth.
  • Install some oscillating fans, which help with temperature and aid in preventing mold.
  • Make sure that your growing room is sealed and insulated.
  • If all else fails, try supplements. These can help make your plants become more resistant to warmth and recover better from heat.

Unique concerns for outdoor growers

Indoor growing helps you evade the common issues found when growing cannabis outdoors. It’s much easier to get the best temperature to grow marijuana in a controlled setting.

That said, you can try these solutions and suggestions if you prefer the idea of growing outdoors.

Greenhouses and cold frames

Getting a greenhouse will help you control the ideal temp and humidity for cannabis. The best choices for cannabis growth include polytunnel, lean-to, and freestanding greenhouses.

If you’re looking for something a bit smaller, you can always opt for a cold frame. It protects your cannabis from cold weather while still getting heat from the sun. They’re cheaper than a greenhouse and suitable for small-scale outdoor growing.

Patio heaters

Patio heaters are perfect for cold regions and will help keep your plants warm. You can also opt to use it only at night.

Compost piles

Compost generates heat while it decomposes and so will naturally make the surroundings warmer. Placing compost piles near where your cannabis grows will aid by raising the temperature.

Choose the right seeds

The optimum cannabis germination temperature is 78°F/25°C. That said, there are slight variations according to strain. The rule is that indica is better for cold temperatures, while sativa is better in warmer climates.

Drying and curing

Drying and curing aids in making your buds not only smell better but become more potent as well. You need to ensure while drying cannabis buds you retain the temperature at about 68°F/20°C, and three days later, at about 61-64°F/16-18°C.

Curing is best done slowly at low temperatures. Some connoisseurs even leave their buds to cure for up to a year!

FAQs related to cannabis temperature

If you’re looking for simple answers to complex questions, read through our frequently asked questions.

What temperature does cannabis grow best at?

Temperatures can vary, but for the most part, the best marijuana-growing temperatures are between 20–30°C/70–85°F during the daytime. At night the best temperature to grow weed is 25°C/75°F.

Can a negative temperature differential make the cannabis plant sick?

You can use a negative temperature differential to keep your plants stocky and short. However, it can harm certain strains, so you need to do research beforehand to determine whether it’s safe or not.

Can fluctuations in temperature stress cannabis?

Yes, it’s important to moderate the temperature as much as possible. A stressed plant will begin to get yellow leaves, and brown spots can begin to appear.

Can indoor temperature swings damage cannabis?

Yes, it’s crucial to maintain consistent cannabis-growing temperatures. If the temperature is too high, it can degrade terpenes and stress the plant, resulting in damage. If the temperature is too low, it can damage nutrient uptake and negatively affect growth.

What is the best temperature for drying cannabis?

The best grow room temp, and humidity for drying cannabis is more or less 70°F/21C° with a humidity of 50%.

What temperature will the buds on a marijuana plant stop growing?

At below 15°C/59°F, marijuana plants will struggle to grow and may end up dying. Cold temperatures slow the rate of photosynthesis. It helps to refer to a cannabis temperature chart if you’re unsure about a specific strain.

What humidity should the marijuana grow room be?

The humidity for growing weed should be upwards of 70% at the initial stages, but you should reduce it to 40–50% as it reaches the flowering stage. It can go up to 60% during the vegetative stage.

What is the lowest temperature cannabis can survive?

The lowest weed growing temperature depends on the strain. However, as a rule of thumb, anything below 50°F/10°C will cause a lot of strain on the plant.

An important variable

As you can see, determining the optimum weed temperature plays an essential role in the growth and survival of cannabis plants. The fruitfulness and survival of your plants is all determined by the effective implementation of temperature control.

At i49, we have the right seeds for you and your unique temperature concern. Check out our website to see what we offer.

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    How to grow marijuana outdoors

    Growing marijuana outdoors is great because you won’t need to spend a ton of money on it and you can rely on the power of the sun. If you have access to a sunny spot in a private yard or even a balcony, terrace, or rooftop, you can grow weed outside. You will be tied to the sun and the seasons and local weather, but you won’t have to spend a bunch of money on equipment and utilities like indoor growers.

    If you’re growing weed outdoors, it’s great to find a community of cannabis growers in your area to see how others are growing in your specific climate. Local climates vary, so it can be helpful to see what strains thrive where you are, and also when other growers are popping seeds, harvesting, and more. You can also join online forums or Social media groups, but a great place to start is your local grow shop.

    Benefits of growing weed outdoors

    Low costs

    Relying on the power of the sun, you won’t need to spend a ton of money on an outdoor grow. You’ll need some soil, fertilizer, seeds or clones, and maybe a small greenhouse to get them started. You won’t need to pay for electricity for lights, AC units, or dehumidifiers, and you can even collect rainwater.

    Big yields

    The sky’s the limit with outdoor plants—you can let them get as big and tall as you want, as long as they’re manageable. One plant can potentially yield between a half-pound and full-pound of dried weed! Growing a handful of hands for yourself is more than enough. With an indoor grow, your space is a lot more restricted.

    Environmentally friendly

    Indoor grows can be wasteful, using a ton of electricity to power all those lights, fans, and other equipment. The sun and the wind are free!

    It’s fun and relaxing

    Don’t underestimate the therapeutic value of gardening. It’s relaxing to spend some time outside, roll up your sleeves, and get your hands dirty for a while. And there’s nothing better than smoking something you grew yourself.

    How to set up your outdoor marijuana grow

    Here are some important considerations before starting an outdoor marijuana grow.

    Climate in your area

    It’s crucial to have a good understanding of the climate in the area you’re going to grow. Cannabis is highly adaptable to various conditions, but it is susceptible in extreme weather.

    Sustained temperatures above 85°F will cause your plants to stop growing, while continued temperatures below 55°F can cause damage and stunting to plants, even death.

    Heavy rains and high winds can cause physical damage to plants and reduce yields, and excessive moisture can lead to mold and powdery mildew, especially during the flowering stage.

    Choosing the best outdoor cannabis grow site

    Once you have an understanding of the climate in your area, you’ll need to consider a few things before planting your weed.


    Weed plants will need full, direct sun for at least 6 hours a day. You may have a backyard, but it might not be great to grow there if it doesn’t get full sun every day.

    Your cannabis plants should receive as much direct sunlight as possible, ideally during midday, when the quality of light is best. As the season changes and fall approaches, your plants will get less and less sunlight throughout the day, which will trigger the flowering stage.

    Having a constant breeze is good for your plants, and especially in hot climates. But if you live in an area with a lot of high winds, consider planting near a windbreak of some sort, like a wall, fence or large shrubbery.

    Privacy and security

    You also want to consider privacy and security. A lot of people want to conceal their gardens from judgmental neighbors and potential thieves. Tall fences and large shrubs or trees are your best bet, unless you live in a secluded area. Also, most state laws require that you keep cannabis plants concealed from the street.

    Types of outdoor grow spaces

    Some growers plant in containers on balconies or rooftops that are shielded from view, while some build heavy-gauge wire cages to keep thieves and animals at bay. Whatever you decide, think about how big you want your final plant to be—outdoor cannabis plants can grow to 10 feet tall or even more, depending on how much you let them go.

    Garden plot: Probably the most common outdoor growing spot, many will plant cannabis alongside other growing veggies.

    Balcony: This can be a great spot if it gets good light—ideally, it faces south—and will usually get good wind. However, you may need to cover your balcony from peeping neighbors.

    Roof: This can be great for sun but may have too much wind.

    Soil and other media for outdoor cannabis growing

    Soil, at a basic level, is defined as the topmost layer of earth in which plants grow—it’s a mixture of organic remains, clay, and rock particles. Cannabis plants thrive in soil rich with organic matter, and they need good drainage.

    Most outdoor weed growers will either dig a hole and add fresh soil for the plant, or grow their weed in pots. This will allow you to better control the growing medium and the amount of nutrients your plants receive.

    You can plant directly into the ground, using the preexisting soil, but you’ll need to understand your soil’s composition and amend it accordingly. If you go this route, we recommend getting your soil tested, which will minimize headaches, and it’s easy and relatively inexpensive. A soil test will tell you the makeup and pH of your soil, any contaminants present, and will recommend materials and fertilizers to amend your soil.

    Soil has three basic consistencies, in various ratios:

    Soil also varies in:

    • pH level
    • Water retention
    • Texture
    • Nutrient makeup
    • Drainage

    Silt soils

    Silty soil is the ideal growing medium. It’s easy to work, warms quickly, holds moisture, has good drainage, and contains a lot of nutrients. The best silty soil is dark, crumbly loam—it’s fertile and probably won’t need any amending.

    • Medium granular size
    • Naturally fertile (contains nutrients)
    • Retains water
    • Stabilizes plants
    • Poor drainage
    • Easily compacted

    Sandy soils

    Sandy soil is easy to work, drains well, and warms quickly, but it doesn’t hold nutrients well, especially in rainy environments. You’ll want to dig large holes for your plants and add compost, peat moss, or coco coir, which will help bind the soil together.

    In hot climates, sandy soil should be mulched to help with water retention and to keep roots from getting too hot.

    • Large granular size
    • Low pH
    • Good drainage
    • Prevents compaction
    • Easy to work with
    • High oxygen levels
    • Poor water retention
    • Dries out quickly
    • Nutrients get washed away

    Clay soils

    Heavy clay soils drain slowly and don’t hold oxygen well, so they will need to be heavily amended. A few weeks before you plant, dig large holes where you’ll be placing your weed plants and mix in big amounts of compost, manure, worm castings, or other decomposed organic matter. This will provide aeration and drainage, as well as nutrients for the plants.

    • Small granular size
    • High pH
    • Provides minerals
    • Retains water
    • Stabilizes plants
    • Poor drainage
    • Heavy soil
    • Hard to work

    Loam soils

    While some plants thrive in their native soils, which are usually one of the compositions listed above, cannabis plants are best grown in soil that includes a combination of the three consistencies above—this mixture is known as loam.

    The best way to identify loamy soil is by touching it. How does it feel? Sandy soil should be difficult to compact while clay should compact into a tight ball that won’t crumble. When squeezed, loamy soils should form a loose ball that will hold its structure momentarily before breaking apart in large chunks.

    • Mixture of sand, silt, and clay
    • Near neutral pH
    • Drainage
    • Water retention
    • Naturally fertile
    • Easy to work
    • Nutrient retention
    • Supports microorganisms
    • High oxygen levels

    Most potting soils used in gardening are loam soils. If you’ve ever worked with potting soil, you’ll know that its composition is rich and diverse, and it looks dark and hearty. Beyond texture and color, the soil should smell rich and alive.

    Buying the right soil for an outdoor cannabis grow

    For most first-time gardeners, we recommend buying a quality potting soil that will provide your plants with enough nutrients to get them through most of their growth cycle without having to add many amendments. This pre-fertilized soil—often referred to as “super-soil”—that can grow cannabis plants from start to finish without any added nutrients if used correctly.

    You can make this yourself by combining worm castings, bat guano, and other components with a good soil and letting it sit for a few weeks, or it can be purchased pre-made from a local nursery or grow shop.

    While shopping for soil, you might be overwhelmed by the options available at your local garden store. The soil type is the basic structure of your soil. From there, look at nutrients, microorganisms, and other amendments that improve the soil. Your choices will be flooded with words like:

    • Perlite
    • Worm castings
    • Bat guano
    • Biochar
    • Peat moss
    • Compost
    • Fish meal
    • Bone meal
    • Glacier rock dust
    • Plant food

    These are just some examples of amendments commonly used in different types of soils. Heavily amended soils will have long lists that break down all organic nutrients they contain. Some companies create soils that offer a great structure with base nutrients, but allow you to fill in the gaps as you desire.

    Growing containers

    You may need to put all of your plants in containers if you don’t have great soil. Also, if you’re unable to perform the heavy labor needed to dig holes and amend soil, containers may be the only way for you to grow your own cannabis outdoors.

    If you don’t have a suitable patch of earth to make a garden, containers can be placed on decks, patios, rooftops, and many other spots. If needed, you can move them around during the day to take advantage of the sun or to shield them from excessive heat or wind.

    However, plants grown in pots, buckets, or barrels will likely be smaller than those planted in the ground because their root growth is restricted to the size of the container. In a broad sense, the size of the pot will determine the size of the plant, although it’s possible to grow large plants in small containers if proper techniques are used.

    What size pot do I need?

    In general, 5-gallon pots are a good size for small-to-medium outdoor plants, and 10-gallon pots or larger are recommended for big plants. Regardless of size, you’ll want to protect the roots of your plants from overheating during warm weather, as pots can quickly get hot in direct sunlight. This will severely limit the growth of your plants, so be sure to shade your containers when the sun is high in the sky.

    Fertilizers and nutrients for outdoor soil

    Cannabis plants require a large amount of nutrients over their life cycle, mainly in the form of nitrogen, phosphorus, and potassium. How much you need to add to your plants will depend on the composition of your soil.

    Typically, outdoor growers will add amendments to soil when weed plants are transplanted outside. Outdoor amendments usually come in powder form that you mix in with soil.

    Start off with fertilizers that are inexpensive and readily available. Some release nutrients quickly and are easily used by the plant, while others take weeks or months to release usable nutrients. If done correctly, you can mix in a few of these products with your soil amendments to provide enough nutrients for the entire life of your plants. Most of these items can be purchased cheaply at your local nursery.

    We recommend these organic fertilizers:

    • Blood meal or fish meal for nitrogen
    • Bone meal or bat guano for phosphorus
    • Wood ash or kelp meal for potassium
    • Dolomite lime for calcium and magnesium
    • Epsom salts for magnesium and sulfur

    There are also commercially available soil blends that already contain the proper mix of these types of ingredients.

    For first-time growers, we recommend avoiding commercial fertilizers like long-release granular fertilizers. These can be used, but you need to have a good understanding of how they work and what your plants need.

    We also advise against using nutrients designed for indoor weed growing—they are generally composed of synthetic mineral salts and can damage soil bacteria.

    Again, getting your soil tested can be very useful and will tell you how to amend your soil and what types and amounts of fertilizer to use. If you are unsure how much to use, be conservative, as you can always add nutrients to the top of soil—called “top dressing”—if plants start to show deficiencies.