Best Moon Phase to Germinate Cannabis Seeds: A Lunar Calendar Guide

According to lunar gardening tradition, the best time to germinate cannabis seeds is from three days before the full moon to about a week after it, while the waning moon is for prepping soil, taking clones and pruning. There's little hard science behind moon planting, but plenty of growers swear by it, and everyone knows the moon moves the tides.

Folk wisdom says the phases of the lunar calendar affect not just bodies of water but people, animals and plants too, cannabis strains included. Here's how the lunar calendar works in cannabis growing and how growers use it to their advantage.

What is the lunar calendar?

A cannabis lunar calendar is based on the cycles of the moon and used to track time by its phases, known as lunations. Those phases come from the way the sun, moon and Earth move relative to each other.

Moon-planting tradition holds that the moon has a strong influence on plants, sending out different kinds of light depending on its phase. Moonlight is reflected sunlight and can't drive photosynthesis the way the sun does, but believers say it helps regulate the plant's photoperiod by stimulating light-sensing proteins, and that the moon's gravitational pull affects how sap moves through the plant. Treat these as lore, not established science.

How long is a lunar cycle?

An average lunation lasts about 29 days, 12 hours and 44 minutes. If you're going to plant by the moon, you need to know the difference between the Northern and Southern Hemispheres.

In the Northern Hemisphere, the last-quarter (waning) moon is shaped like a “C,” while in the Southern Hemisphere it looks like a “D.” The first-quarter (waxing) moon is the reverse: a “D” up north and a “C” down south.

When to plant outdoors by the moon in the Southern Hemisphere

When you're planning an outdoor cannabis grow in the Southern Hemisphere, the big question is when to germinate your seeds. The answer depends on several factors, and how much space you have is one of the most important.

The usual move is to start at the beginning of spring, in September (March in the Northern Hemisphere). That gives plants time to get big, which means more buds.

Keep in mind, though, that planting in September won't speed up your harvest. It just gives the plants more time to grow and develop.

For photoperiod plants, the flowering stage is triggered by how many hours of light they get, not by how old they are. So planting earlier won't bring harvest forward.

In short, if you want smaller, more discreet plants that fly under the radar, planting in September may not be your best bet. If you're after bigger plants with a serious bud count, September is a solid call.

What's the best moon phase to germinate cannabis seeds?

Timing your germination right can make a real difference in how your grow turns out. According to folk wisdom and the experience of many growers, the sweet spot is from three days before the full moon to roughly a week after it.

Moon gardeners consider this the best window for seedlings to get off to a strong start. Mixing your growing medium, they say, is best done between the waning moon and the new moon.

That same lunar stage is considered a good time for taking clones and pruning, since plant tissue is said to heal faster, which helps keep plants healthy and growing.

What's the best moon phase to feed cannabis plants?

When it comes to feeding your cannabis plants, lunar growers believe the moon phase affects how well they take up water and nutrients. From the start of the full moon to the end of the waning moon, plants are said to absorb more water and nutrients from the soil.

That makes this window the traditional time to apply fertilizers and nutrients, so the plants make the most of them and grow healthy.

The waxing moon, on the other hand, is considered a good time to make compost and deal with pests.

During this stage, the thinking goes, plants regenerate better, so tackling these jobs is more effective and more likely to pay off.