Growing Weed in the Fall: Best Practices for an Autumn Outdoor Grow

Growing weed in the fall works best with cold-tolerant autoflowers or clones, some protection from frost (a simple homemade greenhouse goes a long way), containers raised off the cold ground and morning watering. Fall's longer nights push photoperiod plants straight into flower, so you don't have to touch the light cycle. This guide covers those best practices with an eye on outdoor grows in Argentina, where fall runs from March to June and rolls into a cold winter, plus a beginner's rundown of outdoor growing in general.

Pick cold-tolerant strains

The first thing to think about for a fall grow is choosing cold-tolerant strains. With temperatures starting to drop, you want genetics that can handle cooler conditions. Autoflowers like Northern Lights Auto or Critical 2.0 Auto are popular picks because they flower on their own and handle changing light conditions well.

Clones or autoflower seeds

If you're starting new plants in the fall, consider using clones that are already flowering. They'll keep flowering under the short days and speed up the whole process. The other option is autoflower seeds, which don't depend on the light cycle and will grow vigorously in the fall.

Protect your plants from the cold

In Argentina's winter, nights can get really cold, which puts your cannabis plants at risk. To avoid cold damage, use a homemade greenhouse or a similar structure. It shields your plants from extreme temperatures and keeps frost from wrecking your grow.

Raise your containers

Get your containers off the ground with stands or insulating material. That keeps the roots from getting chilled and helps hold a steadier temperature. Dark-colored containers can also help keep roots warmer and happier.

Keep an eye out for pests and disease

Winter can bring pests and diseases too. Inspect your plants regularly and use pest control if you need it. Keep the area around your plants clean so bugs and diseases don't build up.

Watering and nutrients

Adjust your watering so the growing medium doesn't freeze on cold nights. Water in the morning so the roots can take up the water before the nighttime chill sets in. Feed your plants properly to help them handle the tough weather.

Let the natural light cycle do the work

In the fall, the natural photoperiod shifts and nights get longer. Cannabis plants take that cue and go into flower with no fuss. You won't need to adjust the light cycle, which makes things easier.

Harvest at the right time

Harvest usually lands in November or December in the Northern Hemisphere (May or June in the Southern Hemisphere), though the date can vary by strain. Check the trichomes to nail the best moment to harvest. Your plants should be at peak maturity.

Bud quality

Keep in mind that fall-grown buds can look a little different. They may have more small leaves than summer buds. But that can actually work in your favor if you're planning to make resin extracts, since these buds tend to carry plenty of trichomes.

Outdoor growing for beginners

To grow cannabis outdoors, the bare minimum is some basic gardening tools, soil, water and a spot in your yard or garden that gets lots of sun.

Cannabis is a tough plant that has adapted to climates all over the world. Over time it's had to evolve defenses against a whole range of problems. Still, it's vulnerable to extreme weather. Whether it's strong winds snapping branches or too much rain causing mold, outdoor growing can throw challenges at you that a little planning can help you avoid.

Getting to know your local climate and seasons is one of the most important steps to growing high-quality weed outdoors. So when people ask when to plant cannabis outdoors in Argentina (or anywhere), our answer is to keep these points in mind:

Temperature

Daytime temperatures of 24–25 °C (75–77 °F) are ideal for cannabis, while anything above 31 °C (88 °F) or below 15 °C (59 °F) can slow growth. Cannabis is considered heat-tolerant, but extreme highs and lows can cause serious problems.

If you're just getting started, check out our Successful Growing online course (in Spanish). 

Good training is key! 

Season

In the Southern Hemisphere, cannabis can be planted in early to mid-spring and harvested in mid-fall: September through April is ideal. In the Northern Hemisphere, that's roughly March through October.

Light

Light is what leaves a lot of growers wondering how many hours of sun an outdoor plant needs.

During the first half of the season, the days get longer until the summer solstice. In veg, the plant builds the roots and stems that will support it all the way through flowering.

After the solstice, the hours of daylight shrink, which naturally pushes the plant into flower. Cannabis is a short-day plant, meaning it starts flowering as the nights get longer and the hours of sunlight drop.

Most plants start flowering once they get less than about 15 hours of sun a day. That's why you need to plan where your plants go, factoring in the temperature and light where you live, so they have time to finish flowering before the cold, rainy weather shows up.

Soil

Good soil is dark, rich in nutrients and light and fluffy in texture. It needs to hold water but also drain off any excess. The soil itself should be slightly acidic, with a pH around 6. You can check that with a pH meter.

How to grow weed outdoors, step by step

Genetics

Once you've picked your spot, it's time to choose a strain. For that, think about your growing conditions and the kind of high you want.

If you live somewhere with a short growing season (farther from the equator, like the northern US or southern Argentina), go for tough, fast-flowering genetics like autoflowers. If you live somewhere with a long, warm season (closer to the equator, like northern Argentina), tall sativas that take longer to flower and hybrids that thrive in those conditions are your best bet.

If you want your outdoor weed to have a specific flavor, look into the terpene profile of the strains you're working with. 

Last but not least, use the seed bank's info to estimate the size, flowering time and yield of the strain you like best.

How to germinate cannabis seeds outdoors, step by step

During germination, when the seed puts out its taproot and becomes a seedling, three things need to be in place: darkness, moisture and water. Together, they wake the seed up. And soil gives it the most natural place for that to happen. Depending on where you live, keep the following in mind: 

Warm climates:

You could germinate your plants directly in containers or garden beds outside. But as we said above, cannabis needs plenty of humidity during the seedling stage, so consider doing it in a greenhouse or polytunnel.

Cold climates:

Growers can germinate seedlings indoors while the last spring frosts pass. Once the weather warms up, transplant them straight into the ground or into big containers outside.

Before germinating your seeds, find good-quality soil for your outdoor grow. Organic soils give your plants everything they need to thrive: nutrients plus beneficial bacteria and fungi. The right outdoor soil makes a huge difference in how well your plants grow. 

 

Now that you know to prep good soil for your outdoor grow, it's time to germinate your seeds. Poke a hole in the top layer of soil in your garden bed or container. Drop the seed in and gently cover it with soil. Add a little water. The first sprout will pop up within 2 to 7 days.

The seedling stage lasts about two weeks. During that time, give it steady light, humidity around 70% and a little water.

The vegetative stage outdoors

The vegetative stage comes after the seedling stage. During this time, your plants photosynthesize and start building energy for growth, and big fan leaves start popping out everywhere. To keep your plants healthy, especially outdoors, keep the following in mind:

Watering:

The classic rookie question is how often to water outdoor cannabis. Our advice: water only when the top 3–5 cm (1–2 in) of soil is dry. If you don't wait long enough, your plants could get root rot and other problems.

Check your soil: 

Outdoor grows, just like indoor ones, need a soil check every now and then to make sure the pH sits at 6.0–7.0 (the sweet spot for nutrient uptake).

Containers vs. ground

Growing weed in containers can be handy, since you can move your plants around the yard to chase the sun or protect them from rain, strong winds or extreme temperatures.

Nutrients

Good soil should have enough organic nutrients to kick off the growing cycle, but as the plant grows and moves into flower, it can use up what's available and need extra fertilizer.

The three main nutrients for growing cannabis are nitrogen, phosphorus and potassium. In veg, plants need more nitrogen to build the roots and leaves that support flowering. Early in flower, they need more phosphorus and potassium than nitrogen. Late in flower, once most of the nitrogen is used up, plants focus on using whatever nutrients are left.

Ideally, pick a nutrient line made for cannabis and follow the suggested doses so you don't overfeed or underfeed. Organic nutrient sources are best because they come with beneficial microbes, but they can take longer to break down and become available to the plant.

Water

How often to water outdoor cannabis is easy to figure out: wilting plants and dry soil are a clear sign they need water. Droopy leaves with wet soil are a sign of overwatering. Both are common mistakes you'll learn to avoid with a little practice.