Planting Cannabis Outdoors in Summer: Is It Too Late, and How Timing Controls Plant Size

Summer weather helps an outdoor cannabis garden with long days and plenty of sun, but extreme heat can stress young plants and cook the roots in dark containers, and the later in summer you plant, the fewer light hours your plants get to grow before they flower. Growing weed outdoors has real perks, including the chance to harvest higher-quality buds, and if you're lucky enough to have a good outdoor spot, it can be a rewarding, productive project.

Before you dive in, though, you need to think about a few things, including whether it's legal where you live and whether your space is actually suited to growing cannabis. Here we'll go through the pros and cons of growing weed in your yard or garden during the summer, plus some practical tips to pull it off.

Can you still plant cannabis in summer?

Whether you can plant cannabis in summer depends on your region and local climate, but in many cases it's doable as late as February in the Southern Hemisphere (around August in the Northern Hemisphere). Just keep in mind that as summer goes on, the plants get fewer hours of light, which can limit their growth and final size.

Whether you're growing photoperiod strains or autoflowers, you'll need to take some specific precautions when growing cannabis in summer. One of the biggest challenges you'll face is extreme heat.

How to protect a summer cannabis grow from the heat

To protect young plants from excessive heat, you need to shield them from the sun, especially during peak hours, usually between 11 a.m. and 4 p.m. Long exposure to the sun during that window can dry out seedlings fast and, in extreme cases, kill them.

Use shade cloth or other covers to cut the intensity of the sun's rays and give your plants a better environment to grow in.

How to keep your growing medium cool

It's also important to protect the growing medium from high temperatures. Light-colored containers and keeping them off the hot ground can help prevent too much heat transfer. For example, a black container in direct sun can push the temperature of the growing medium to levels that stress your plants, easily topping 40 °C (104 °F).

Lifting containers off the ground with materials like Styrofoam or wood, and grouping plants together so they shade each other, are good ways to keep things cooler and better for growing.

Mulch and ground covers can also help bring down container temperatures and keep the growing medium moist for longer. Some cover crops, like clover, even add extra nutrients, so they don't just help maintain soil conditions, they also help your plants grow healthy.

When is the best time to plant cannabis outdoors?

In the Southern Hemisphere, including Argentina, the outdoor growing season usually starts in September and runs until harvest, which can land in May, June or even July for some late-flowering strains. In the Northern Hemisphere, shift that six months: the season starts around March.

If you'd rather go fully natural and not mess with your plants' photoperiod at all, you can still steer the outcome with timing: within the season, when you plant is how you control how tall your plants get. (Messing with the light, which we'll cover below, works two ways: stretching days or shortening them.)

In-ground vs. containers: how planting date affects plant size

For example, if you plant straight in the ground at the start of the season (September down south, March up north), your plants can get huge before they even start flowering, reaching 2 meters (6.5 ft) or more with some strains.

Plants that big will need a solid staking system and, in some cases, trellis netting to hold up the weight of the buds. Big plants are also a lot less discreet than small, compact ones.

If you're growing in containers, you'll run into similar challenges: you'll need to transplant or add extra fertilizer to keep up with big plants.

To control plant size, you can use techniques like topping, tying down branches and root pruning. But careful planning and planting at the right time are simpler, more effective ways to do it.

Do you need to add light to an outdoor grow?

Sometimes you may need to tweak the light to speed up or delay flowering. Delaying it is easy: energy-saving bulbs or high-power grow lights can extend the photoperiod so your plants reach a good size before they flip to flower.

Speeding up flowering, on the other hand, takes more work, like using blackout tarps (light deprivation) or even moving the plants into a dark space to trigger flowering.

Whatever technique you use, keep the photoperiod consistent to avoid unnecessary stress on your plants and make sure they develop healthy through the whole growth and flowering cycle.