Male and hermaphrodite cannabis plants

Generally, when you grow from regular seeds, you’ll end up with around half of the plants turning out as female, the other half male. This can mean a lot of wasted space in the grow room, which is especially a problem for home growers with little space to begin with. Feminized seeds help with this problem by offering growers seeds that are 99.99% female. However, there is a chance of the plant turning male or becoming a hermaphrodite a.k.a. hermi. A hermi plant is a female plant that produces male flowers, causing the same issues that a male plant would cause in the grow room.

The vast majority of feminized seeds will not turn hermi, however there seem to be a few common factors that can influence this. We have generally found that growers with smaller set-ups are more likely to have this problem. Heat can be a major issue in smaller grows, because it can stress the plant. There are also other factors that can cause a plant to turn hermi, but they can all be controlled. The temperature in the grow room should be below 30°C, with 20-25°C being the ideal temperature, especially during the first few weeks.

Light is another major factor; both the strength/amount of light and the type of light. Generally we advise no more than 40,000 lumens per square metre, this works out to one 400 watt per metre, roughly 60 cm from the plants. When your plants start flowering, you can increase the amount of light to help the buds develop more.

We have also found that too much red light can cause hermis; we recommend Son-T Agro or Green Power, which are used for growth and bloom, and have less red light and more blue. We advise against using Son-T Plus bulbs as they have too much red light; they are good for flowering but not so good for growing feminized plants.

The quality of the soil or grow medium is also important. Soil with an NPK of 12-14-24 are best for growing female plants. The soil or grow medium should also never become too dry as this can also stress the plant.

In short, when growing feminized seeds, you want to avoid too much light; especially red light, high temperatures, dry grow mediums and low nitrogen or high potassium nutrients.