Growing Cannabis by Latitude: When to Plant Wherever You Live

Your latitude sets your outdoor cannabis calendar: it controls day length (the photoperiod), and day length tells the plant when to grow and when to flower. Far from the equator you get one big season with a clear planting window; near the equator you can grow year-round, but sativas do better than indicas.

So when should you plant weed where you live?

When you're starting a grow, there's a lot to think about: finding the right spot, the gear you'll use, even the strains that suit your taste. But there's one huge factor every grower needs to keep in mind before planting anything: latitude, or put simply, where on the map you live.

Latitude directly affects the photoperiod, meaning how many hours of light and darkness you get in a day. It also defines the planet's big climate bands.

Cannabis is an annual plant: it germinates, flowers and gets harvested within a single year, and every stage is tied to the photoperiod. So depending on where you are on the globe, some months are better for growing than others. To break down growing cannabis by latitude, we'll look at three zones: the Northern Hemisphere, the Intertropical Zone and the Southern Hemisphere.

Growing Cannabis in the Northern Hemisphere

This is the part of the planet north of the equator. The longest day of the year (the summer solstice) falls between June 20 and 23, and the shortest (the winter solstice) between December 20 and 23. Day and night are the same length (the equinoxes) around March 20 and September 22.

For growing cannabis, we'll use two areas as reference points: the Iberian Peninsula (Spain and Portugal) and the Canary Islands.

Growing Weed on the Iberian Peninsula

It sits between 36° and 44° North, roughly the same band as the US from central California up to Oregon. You can grow almost any strain here in great conditions. The only ones that might give you trouble are the most equatorial sativas, which can keep flowering until the end of November or even into December.

The ideal months to plant are March, April, May or June. If you want to plant in July or August, go with autoflowers.

If you're growing on a balcony or terrace or in containers, April and May are the best months to plant early-finishing strains. You can plant in June if you want to keep height in check or shorten the grow for sativa-heavy strains. And remember that cannabis wraps up its cycle in fall, so depending on your latitude, pick faster strains you can harvest before the cold and heavy rains roll in.

Best Strains and Timing for the Canary Islands

The islands sit between 27°37' and 29°25' North, with a mostly subtropical climate that can vary with altitude and which side of the island you're on (north or south), apart from a few cooler microclimates. Depending on the strain and the kind of harvest you're after, plant from March to June, or from September to November for a March harvest.

Growing Cannabis in the Intertropical Zone

This is the band between the Tropic of Cancer and the Tropic of Capricorn. Day length barely changes over the year here.

Right at the equator, days stay close to 12 hours all year; as you move toward the tropics, the gap between the longest and shortest days grows to a couple of hours, and the timing flips depending on whether you're north or south. On the Tropic of Cancer, for example, the longest days (around 13 hours of light) come between May and August, while on the Tropic of Capricorn they fall between November and February.

Because of this photoperiod, you can grow cannabis year-round, and plants behave a lot like autoflowers: they switch into flowering on their own once they're mature.

One thing that can trip you up is rainfall. Plan around the dry and rainy seasons to pick a good harvest month. Ideally, keep direct rain off the plants during flowering. A cover that lets light through can solve the rain problem, though keep in mind that anything that makes the sky "cloudier" for your plants tends to mean a smaller harvest.

In the tropics, indicas don't grow with the same vigor they show farther from the equator. On the other hand, tropical conditions are perfect for sativas, landrace strains and commercial strains with tropical genetics.

Growing Cannabis in the Southern Hemisphere

This is the part of the planet south of the equator. December 21 is the longest day of the year, and from then on the days start getting shorter. The shortest day comes on June 21 with the winter solstice. On March 21 and September 21, day and night are the same length: those are the fall and spring equinoxes.

Which Cannabis Seeds to Grow in Argentina, Chile and South Africa (33° to 50° South)

Here, the best time to start your grow depends on altitude and frost risk, both at planting and at harvest, depending on the area. You also need to match the strain to the month you plant. (Growing up north? Shift every month below by six: September becomes March, January becomes July.)

For experienced growers chasing big plants, September and October are the ideal months to start. Autoflowers are a smart choice too, since their speed sidesteps problems like salt buildup or pests that can show up over the 5 to 9 months a full photoperiod grow can take. Keep an eye on the weather, because there's still a risk of frost.

To avoid trouble with cold snaps, start your grow in November or December. Plants will thrive with the 14 to 15 hours of sun that time of year, and with good growing conditions you can get nice, big plants.

January, on the other hand, is the ideal month if you want to grow sativas that won't top 250 cm (about 8 ft). You can also grow indicas, which won't get very big but will develop just fine. Autoflowers are a good call right up to the end of February, which is also when you can start strains with tropical genetics.

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