Grow Calendar For Northern And Southern Europe

Zamnesia wants to make sure you get your timing and species selection spot-on to produce luscious crops every grow season. Whether you live in Northern or Southern Europe, let us help you germinate at the right time for vigorous vegetation and big yields.

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Choosing the right strain for your climate also plays an important role, and we have got you covered there as well. Following these general guidelines will get you plenty of sticky icky in the jar come harvest time, while avoiding weak germination, poor vegetation, fluffy buds, low yields, and dreaded pathogens.


Cannabis Seeds

It goes without saying that different cannabis strains display different characteristics. They look different as they grow, have differing bouquets, and a wide range of effects. Depending on the growing climate, strain selection can involve more than phenotype, flavour, and effect. Cool, wet climates with short days demand a more hardy selection that flowers quickly, while warm and humid coastal areas can sustain strains that enjoy a lot of sun and flower over a longer period.


When To Purchase Your Seeds

Whether you are in the North or the South, or if you are using supplemental lighting to extend the vegetative phase, buying and germinating seeds is purely academic. You could get underway in the middle of winter and have quite large plants to put outside once the days lengthen, or only germinate the month before they are to go outside, just to get a head start. It entirely depends on the available growing space. And then there are greenhouses.

For the purist who wants to follow the timetable nature has set, and lives in Northern Europe, buying cannabis seeds in late April for germination in May will ensure plants receive plenty of light for proper vegetation.

Wind the clock back a month for those in the Southern climes. Allowing time for delivery, purchase seeds ready for germination as the rest of nature stirs in response to spring; buy late March and early April for a germination in April.

Be part of an age-old debate among outdoor and indoor growers alike: Does the full moon and planting time have an effect on plant quality? Some say it doesn’t matter—cannabis is a very vigorous plant and will grow under any circumstances. Others claim that planting 4 days to a week before a full moon increases the germination rate and produces a more robust plant with more vigorous growth. If you have the room, try comparing plants germinated 1 week after the full moon to others germinated 1 week before. Even under lights. Develop your own lore.


Northern climates are typified by cooler average temperatures, shorter days, and shorter growing seasons. There are a number of species of cannabis that have been developed to thrive in the challenging Northern environment. Species with short flowering times or those with autoflowering genetics can be ready for harvest much sooner than many standard photoperiod strains.

With cooler air and less evaporative sunshine, strains with a high mould resistance will get to full maturity with less susceptibility. Strains with a heritage in the mountains and a naturally high tolerance to cold will also do better than those with tropical heritage.


Indicas and indica-dominant strains are your friends in Northern Europe, as are autoflowering strains. Since the cannabis diaspora over 12,000 years ago, indicas have developed genetic characteristics dictated by their evolution in cool mountain regions with early, then intense winters, and short summers.

Autoflowering strains have a number of advantages, with one of them being that an extra crop can be harvested per year, thanks to the ruderalis genetics. This subspecies evolved in Central Asia, where cold tolerance and early propagation opportunities were a distinct advantage. Indica autoflowers get a double whammy of cold tolerance and quick-flowering genetics.


Southern climates are typified by warmer average temperatures, longer days, and longer growing seasons. Cannabis originally evolved in these types of climates before it was spread all over the world. There is something deep in cannabis genetics that makes it thrive in warm, sunny, and humid climates.

All species of cannabis will respond with vibrant life in warmer and sunnier climates. Species that need a long growing season to reach maturity can be grown more successfully the closer to the equator you get. Grows in humid or rainy environments will benefit from mould-resistant varieties. Warmth always means more bugs, so strains with a combination of resistance to pathogens and insects are always the least troublesome.


Growers in hot and dry microclimates will be able to grow whatever they like really. Most sativas a very tolerant to direct sunlight, where other species will perform better when shaded. Contemporary sativa-dominant hybrids can be grown for all the sativa benefits, with flowering time sped up significantly. Autoflowers will stretch and fill out more under the more intense sunlight and longer days. All species will generally display larger overall size and volume, with more stretch during vegetation.

Humid southern coastal microclimates still get the benefits of lots of sun. Humidity can be a challenge, especially during flowering when thickening flowers can become susceptible to mould and other pathogens. Mould resistance is usually a feature of heavy resin production, which has the added benefit of providing pest resistance. Choosing mould-resistant strains will prevent the heartache of bud rot, especially if an area gets sea mist, fog, and regular rainfall.


Artificially extending the daylight period of plants grown outside with supplemental lighting for up to 18 hours means that when natural springtime comes along, plants will already be substantially advanced, and in some cases—when there are facilities available—can reach 5–10 metres tall. This isn’t for everyone as it depends on a country's laws and having the space or the facilities to pull it off. Nice to dream though—mmh, ten metre cannabis trees!


What’s green and shaped like a house? Not a greenhouse, but a quick note on greenhouses. Greenhouses, especially if you are allowed by law to grow weed, can be the best of both indoor and outdoor worlds. When protection from harsh trichome-withering weather and modification of the immediate environment and photoperiod are required, a greenhouse can be your best friend. Greenhouses are an especially welcome grow setup in northern climates. Even so in the south, but they can be a challenge to cool in the height of summer.


Northern Climates Cool Northern Latitudes

Every outdoor cannabis grower relies on accurate climate data and weather forecasts to plan a crop from seed to harvest. This coming growing season, ganja farmers in the Netherlands and surrounding countries will rise to the challenges of cultivation in an oceanic climate. We have created this grow calendar as a roadmap specifically for the Northern European cannabis road warriors.


  • Day length: 9.05 - 10.47 hours

  • Average temperature: 2.5 °C

February is far too cold and dark to rush outside and start sowing seeds in the dirt. Temperatures will be close to freezing by day, and may dip below zero overnight. The online climate charts will tell you to expect approximately 10 hours of sunlight this month. In reality, you won’t see much sunshine through overcast skies. There is also still a significant risk of snowfall. This is the month to research cannabis seed genetics, weather forecasts, and to gather supplies. Most of the essentials like soil and fertilisers can be found online. But it may take a couple of weeks before all the deliveries arrive.


  • Day length: 10.51 - 12.52 hours

  • Average temperature: 4.7 °C

Still too cold outside. Probably pretty cloudy most days as well. But you can kick-start the grow like a pro indoors. By now, you should be in possession of all the outdoor cultivation essentials. With a minimal investment, you can acquire a basic CFL lamp and reflector to start seedlings indoors. Whether you are growing from seed or using clones from a trusted source, it helps to get plants rooted before you put them outside.


  • Day length: 12.56 - 14.48 hours

  • Average temperature: 8.2 °C

By the middle of the month as daily sunlight increases to about 14 hours, you can begin to make a move outside with plants in 10–20l pots. Temperatures will be in the low teens at best, so only the strong will survive outside this early. Hardy autoflowering strains are definitely the best option. Blue Cheese Automatic by RQS or Early Skunk by Sweet Seeds are rapid bloomers and cold-weather-hardened.

Although tough photoperiod hybrids like Durban Poison by Sensi Seeds or White Critical Express by Kalashnikov Seeds will receive sufficient sunlight for vigorous vegetative growth, late-blooming sativas are to be avoided as the growing season is just not long enough in northern latitudes. Old-school Holland’s Hope and Early Girl will perform well in a greenhouse. But if you want high-grade weed, you need to be a little more patient.


  • Day length: 14.52 - 16.20 hours

  • Average temperature: 12.3 °C

Purists can germinate seeds and start them on a sunny windowsill. As daily sunlight reaches 15 hours and the temperatures stay consistently in the low-mid-teens, it’s finally the right time for most to grow outdoors. Fast-flowering strains are still the best choice. Classic Skunk and Northern Lights by Zamnesia Seeds are solid choices. Alternatively, you can start a dank super auto like Royal Gorilla Automatic by RQS or Devil Cream Auto by Sweet Seeds.

However, if you got started inside, May is the month to harden off and make a move. Start by potting up to large 10–20l final containers. Use your artificial light to supplement the hours of natural sunlight. Using pots allows you to move plants in and out. By the end of the month, they are ready to grow outside permanently.


  • Day length: 16.22 - 16.38 hours

  • Average temperature: 15.2 °C

With a little luck, temperatures will be in the high teens, and by the summer solstice on the 21st, daily sunlight will peak at 16 hours and 38 minutes. Autos germinated in March/April will be ready for harvest this month. Provided they have been sheltered from rain, the buds will be of respectable quality and a decent yield can be expected. Photoperiod strains will vegetate comfortably and still have enough time to grow to large sizes and yield heavily.


  • Day length: 16.37 - 15.29 hours

  • Average temperature: 16.9 °C

Sun-flowered autos started in May will be ready for the chop this month. You could potentially be harvesting your second crop if you get your timing right and selected the right genetics. Most photoperiod strains will still be in vegetative growth and it could be time to do some pruning and training if plants are beginning to turn into trees. Temperatures in the low 20s and 15+ hours of sunlight are great conditions for growing cannabis.


  • Day length: 15.26 - 13.37 hours

  • Average temperature: 16.7 °C

Photoperiod strains will begin slowly transitioning to the bloom phase this month. And if you got a late start with your autos, don’t fret; you still have time to finish flowering this month. By the end of the month, you are back down to about 13.5 hours of sunlight per day. This is not a perfect 12-12 light-dark cycle and is the reason why photoperiod strains take far longer to bloom outdoors. If you have a greenhouse, you can cover it over with light-proof sheeting to reduce the hours of natural light and speed up flowering.


  • Day length: 13.34 - 11.39 hours

  • Average temperature: 14.2 °C

If you haven’t already, now is a great time to build a simple shelter for cannabis plants in mid-late bloom. Heavy rainfall is not uncommon in September. Daily sunlight will decrease from 13 hours and 34 minutes to 11 hours and 39 minutes in 30 days. Be on the lookout for threats to the buds. High humidity and decreasing temperatures to the low teens are a recipe for bud rot. Better to harvest a little early than to lose the crop. Photoperiod plants should be harvested towards the end of the month. September is potentially a third auto harvest month. Autos sprouted in June/July will certainly be ready.


  • Day length: 11.35 - 9.38 hours

  • Average temperature: 10 °C

You had better be close to the finish line to be still growing this late in the year. Temperatures will be 10°C at best and sunlight is fading fast. By Halloween, daily sunlight hours will be back down to single digits. Get trimming and harvest as soon as you can. Winter is coming! November, December, and January are months for hibernating with a fat stash.


Southern Climates Hot Dry Interior And Warm Wet And Humid Coastal Climates

Cannabis, like most plants on earth, germinates and begins growth at the beginning of spring. Celestially speaking, no matter what the actual date is on a calendar, spring is considered to begin around the full moon of March or the Vernal Equinox.

This doesn’t mean that spring signals “germinate some seeds and go” everywhere simultaneously. When cannabis is germinated too early, or when the daylight hours are still below 12 hours, seeds will still germinate, then show sex early and continue to grow into a lovely plant. However, at the important bud stage, they will be fluffy and poorly formed and have disappointing yields. It is tempting to try and get ahead of the curve by planting early, but it always leads to disappointment in the end.

Although frustrating, it is better to wait later in the season until the daylight is at least 12 hours. You will have a slightly smaller plant, but with a considerably heavier yield of much better formed buds.


  • Day length: 9:50–11:02 hours

  • Average temperature: 3–13°C

In February, the days are too short and temperatures still too cold for natural germination. If you have a greenhouse and some supplemental lighting, it is a good time to germinate. Once the plants are established and well-rooted, they will be ready to be put outside to harden off once the weather starts to warm and the days get longer.

February should be spent preparing pots or giving organic gardens a final amendment and mulching. Seeds can be bought in preparation for the oncoming growing season. Be sure to read the breeder's stats to guarantee you get a strain suited to your circumstances.


  • Day length: 11:05–12:34 hours

  • Average temperature: 5–16°C

Time to start germinating your seeds. Some supplemental lighting is still required to assure over 12 hour long days. If you have mother plants, it is time to start preparing them and making clones. By the end of the month, it will be time to put established clones outdoors to enjoy the longer days.

If you are planning on staggering a number of autoflowering varieties for multiple harvests over the coming months, get your first batch going now too; they will be ready mid to late May.


  • Day length: 12:37–13:59 hours

  • Average temperature: 8–19°C

A day length of over 12 hours means no more need for artificial lighting. Plants will germinate in their pots and begin vegetation outdoors. Once the first set of true leaves emerge, growth is noticeable on a daily basis. Putting plants in a place that gets maximum sunlight per day and good air circulation will guarantee optimal growth and vibrant plant health. Begin spraying weekly with a natural insect repellent like neem oil to keep predators in check. Autoflowers planted now will be ready mid to late June.


  • Day length: 14:02–15:06 hours

  • Average temperature: 13–23°C

Plants will now be happy and enjoying the longer days and warmer temperatures. Growth will be speeding up, the leaf sizes will be getting larger, and the plant volume will be increasing. Check soil moisture more often; as plants increase in size, they use more water per day.

Germinating autoflowering strains now means a solid 3 months of ideal growing weather. They will completely fulfil their genetic potential and be ready mid to late July. Autos planted in March will be ready for harvesting now.


  • Day length: 15:08–15:23 hours

  • Average temperature: 14–28°C

Now we are in the sweet spot. Sunlight is at its maximum strength, days are at their longest, and temperatures are in the ideal cannabis growing range. Vegetation will be in top gear. Check soil moisture content more often, as evaporation and transpiration are at their max. Organic and no-till gardeners should be watering with compost teas and other supplements now.

Check the soil temperature—especially in plastic pots—as the days get longer and warmer. Use shade cloth or a cardboard sleeve to protect the pot walls and make sure the top is well mulched. Overly warm substrates encourage root rot, root pests, and slow growth. Plants can show signs of stress like wilting, slow development, and nutrient problems. Poor plant health can attract unwanted pests.


  • Day length: 15:22–14:39 hours

  • Average temperature: 17–31°C

Still in the sweet spot. The day length is starting to shorten, but the temperatures will still remain high. Early-flowering and feminized varieties will start to show pistils. Regular photoperiod plants may be starting to show sex also. Identify and remove males, or isolate them if you are going to be doing some breeding. Continue to check soil moisture and temperatures and maintain pest control methods. Autoflowers germinated back in May will be ready for harvest or fattening up in the last stages of maturity.


  • Day length: 14:39–13:35 hours

  • Average temperature 17–31°C

Longer-flowering autoflower varieties planted in May will be ready for harvesting now. Quicker-flowering cultivars will be filling out substantially. Regular photoperiod plants will have completely established sex by now, displaying small flower clusters with many pistils at each node. Differentiation will have occurred with longer-flowering varieties. Nodes will begin to stagger rather than being symmetrical about the stem. The ends of branches turn up, where the main bud will form and begin to fill out. They will be getting ready for the bloom stretch at this stage.

There is still time to get a reasonable autoflower crop if planting now. Plants will be smaller than those planted before summer, but not disappointing.


  • Day length: 13:30–11:54 hours

  • Average temperature: 14–26°C

Many quicker-flowering and feminized varieties will be ready for harvest between the middle and end of this month. The flowering stretch for regular varieties is well underway and plants may double or even triple in size over the next two months. Buds are nearing their full potential size, but are yet to fill out properly. Aromas are beginning to develop, and trichomes are proliferating quickly on calyxes and sugar leaves. Profit-yielding varieties will need staking to support weighty flowers.

At the end of this month, larger plants can have their upper, more mature buds harvested, allowing more light penetration into the lower parts of the plant. A multi-stage harvest on larger plants will allow for even maturation and bud quality.

With seasonal rains at the end of summer, it is time to be vigilant for pathogens. As buds fatten, they can become susceptible to diseases like Botrytis if they remain wet for too long.


  • Day length: 11:51–10:56 hours

  • Average temperature: 11–21°C

This is the month when things really get exciting. Calyxes begin to fatten properly and pistils start to change colour and die back. Trichomes are starting to swell toward maturity and fragrances are at an all-time high. Purple and blue strains will be getting darker as the weather cools. Exhausted leaves from the lower reaches of plants will yellow, wilt, and drop off.

Most varieties will be ready halfway through or by the end of this month. Watch trichome colour closely for an indication of harvest time.

The final autoflower crop of the year will be brought in now. Unless you have a greenhouse and supplemental lighting, don’t plant any more autos.


  • Day length: 10:23–9:17 hours

  • Average temperature: 6–16°C

Long-maturing landraces or sativas like Haze varieties will be ready for harvest this month. The wait and patience will be well-rewarded as you dismember giant trees with a maniacal smile and a sense of great satisfaction.

Steven Voser
Steven Voser
Steven Voser is an independent cannabis journalist with over 6 years of experience writing about all things weed; how to grow it, how best to enjoy it, and the booming industry and murky legal landscape surrounding it.