growing cannabis in greenhouse during winter

Growing Cannabis in the Winter

In warmer places like here in Spain, growing cannabis during the winter time is quite common thanks to our favorable climate in many areas. It’s quite a different way of growing, as your plants will need some special taking care of if you want to get a decent yield. In this article we’re going to talk about the different systems you can use to get the most yield out of those cold winter months.

The first thing you’re going to need to think about is how plants grow and flower according to the amount of light they receive, and when the days begin to get shorter your plants should begin flowering. This works the other way around too; if your plants are flowering when the days start getting longer they’ll begin revegetating and they’ll go back into the growth period.

Here in Spain, the days begin getting longer on the 21 st of December, so you’ll need to sort something out if you don’t want a bunch of revegged plants. You can do a few things to prevent this:

  • Grow them indoors during September and half-way through October place them in a greenhouse.
  • Plant them later, meaning you’ll need to trick your plants with the light period.
  • Germinate them in a greenhouse.

One of the most important things to keep in mind is that the temperature of the roots can’t go under 16º or they’ll stop absorbing nutrients, causing your plant to stop growing as much. Planting in flowerpots is not the same as planting straight into the ground; flowerpots are much more likely to get cold, whereas underneath the ground tends to be much warmer than above. Plants can but up with cold on their leaves as long as there’s no frost, but if the roots get cold you can kiss your harvest good bye.

The most common winter grows are done in greenhouses. You can grow in flowerpots or straight into the ground because they won’t be as cold in the greenhouse as they would be outdoors. You’ll need to let them grow for around a month or month and a half indoors and then transplant your plants into the greenhouse where they can get a bit more heat at night time. You can also germinate them in the greenhouse from the get go around September, but your plants will definitely be smaller.

If you want, you can make them flower whenever you want but you’ll need to trick them with lights and timers. You can plant whenever you want but keep in mind that after 20 days of growing you’ll need to block out the light somehow with a box, a cover or by sticking them in a dark room. They’ll need 12 hours of light and 12 hours of darkness, so every day at 7am for example you’ll need to take them out into the light and then at 7pm, stick them back into the dark. You’ll need to keep this up for the entire rest of the process until harvest day. Make sure you don’t mess up and forget once it’s flowering or it will begin to revegetate and stop flowering completely, ruining the quality of the half formed buds that you’ll end up with.

If you’re not growing outdoors all you can do is grow under sodium lights, where your plants will develop ferociously and will give you an amazing yield in record times.

When plants are under lights they behave quite differently, because although it may be winter your plants are getting the summer sun every day. They have the perfect climate and you can adjust the parameters as needed. It’s extremely hard to grow indoors during the summer without air conditioning, but it’s perfect for growing in the winter.

If you’re planning on growing this winter you just need to follow these techniques and pay close attention to your plants, harvesting by the end of the year. Remember, tricking your plants with the light periods is something you can do all year round if you want to, not just during the winter.

Author: Fabio Inga
Translation: Ciara Murphy

Growing cannabis in thw winter can be challenging, but we're here with some advice so you can bring your grow to life and get a decent yield.

The pros and cons of growing marijuana in a greenhouse through the winter

Most experienced Canadian cultivators know a thing or two about growing marijuana outdoors, but until recently, a move so bold as openly growing or smoking weed would have been shunned and lead to arrest or fines. Now, due to legislation that came into effect on October 17, 2019, every household may grow up to four cannabis plants at any given time.

Though it’s not quite what so many cannabis enthusiasts had hoped for, it’s more than enough to grow a personal supply, especially with the assistance of an appropriate space that is dedicated to the cause. Unfortunately, with an ever-expanding population and shrinking living spaces, most do not have the luxury of an extra bedroom that can be converted into a grow room, and one solution to that issue is a greenhouse.

If you are interested in the prospect of growing marijuana in a greenhouse, then there are more things to consider than you might think, as it isn’t all sunshine and roses once the setup is erected. There is plenty of hard work and financial investment required to make it really work in the winter, so it is important to consider all the pros and cons before delving in and getting started on building one of your own.


These are a handful of the most popular reasons why so many growers choose to utilize a greenhouse in the winter.

1. Optimal climate control
Every marijuana plant will thrive best once it is provided with the ideal environment in which to do so, and two of the most important factors in this equation are the temperature and humidity levels. You will need a hot and almost sticky humid space for the highest growth rate and cannabinoid content, and a greenhouse can give you all of that and more with the addition of a small heater and a good seal to keep the cold out.

2. A warm retreat
Not everyone enjoys more tropical climates, but those that do will absolutely love having a greenhouse to relax in with a warm cup of coffee, a good book, and a marijuana plant or two at your side for company. Toss on some summertime jams, enjoy smoking weed in the heat, and in no time, you will feel like you’ve finally made it on vacation without ever having to leave your backyard.

3. Enjoy growing marijuana all year long
Growing marijuana outdoors typically requires that the cultivator pay special attention to the time of year in order to get seedlings strong and ready for rooting in time. In Canada, the average growing season begins around the same time as veggies, which is the end of May or beginning of June, and most have crops harvested by October to avoid potential damage from ice-cold frost that can come in at any time.

Those with a greenhouse don’t have to abide by such restrictive seasons that can be unpredictable at best, and since no one wants to lose a whole crop to good old mother nature, many cultivators opt for the protection of an outdoor greenhouse. That way, they can start whenever they want and harvest as it suits them rather than out of haste.

4. Expands on preexisting space
Since most houses these days are designed to save space, they are being made smaller and smaller each year. Though it was once commonplace to have a guest bedroom, storage room, and office on top of the necessary bedrooms, most people are barely making things work with one bedroom to every one or two people that live in the household.

Luckily, even those who reside in townhouses have at least a small outdoor space that could hold a greenhouse the size of a small shed. It might not be big enough to throw a party in or to house a whole veggie garden, but it would be the perfect size for growing four or less cannabis plants.

5. Keeps pests and diseases away
The marijuana plant is a hardy species that can hold a lot, but pests and water-borne diseases can plague and kill off an entire crop quite quickly. Most regions experience a massive decline in the local bug population once the temperatures begin to drop, but not all areas get cool enough to eliminate this fear entirely. A greenhouse can offer protection from both all throughout the year, in the summer and wintertime.


Most good things in life come at a cost, and while the price to be paid for using a greenhouse for growing marijuana isn’t too high, it is one that should be considered so that you don’t come across any unpleasant surprises while partway through this journey.

1. Costly to build
Greenhouses intended for winter-use are built using heavy-duty materials that can cost a fair amount no matter how you go about it. Luckily, some of the cost can be mitigated by finding a used greenhouse online, or by opting for self-assembly rather than hiring a company to do the job for you, but to save money, it would be best to shop smart which takes time and effort.

2. Requires an open outdoor space
Growing marijuana outdoors is a dream for consumers who live in multiple-unit dwellings like apartment buildings with no backyard. Though it is unfortunate, there is no way for a greenhouse to work indoors as it needs even exposure to the light, and even if it could, it would be taking up valuable space and serve a minimal purpose, so, unfortunately, a greenhouse is only a viable option for those who have access to a secured outdoor space.

3. Energy consuming
Most assume that a greenhouse does most of the work for you and that investing in one means skipping over some of the other more costly investments that are required to grow cannabis plants successfully indoors. Unfortunately, most don’t realize that to avoid mold-growth you will need to maintain an air exchange system, and some even find it necessary to add additional heating elements to ensure a consistent temperature. So, it is important to know that even though a greenhouse is relatively energy-efficient, it will make the hydro bills spike a bit more than usual.

4. Breaks easily and expensive to repair
Most people who choose greenhouses for growing marijuana select a style that includes glass panes, which is an effective material for amplifying the heat from that natural UV rays of the sun, however it does have a certain weakness which means that it’s more likely to break if a branch, rock, or moving shelf hits it too hard. Once the seal from the outdoors is broken, the greenhouse effect will no longer be strong enough to maintain the same temperatures, so keeping money on hand for essential repairs just in case is absolutely necessary.

5. Not safe for anyone with heat-sensitive medical conditions
Heat and humidity can be relaxing and even sedating, but it isn’t always safe for people with high blood pressure or any other medical condition that may be exacerbated by intense environment. If you suffer from a pre-existing medical condition, be sure to discuss the possibility of spending large amounts of time in a greenhouse with your healthcare provider.

Weed strains that thrive in colder temperatures

Indica strains are better equipped to handle the difference in the environmental conditions such as temperature changes or humidity.

If you are interested in the prospect of growing marijuana in a greenhouse, then there are more things to consider than you might think.