You should always use organic soil as your medium.
How to get more females to grow from that pack of seeds you purchased. What you need to know about cannabis is that the experience of the grower has so much to do with their female:male ratios when growing from seeds. You can give 5 people the same 10 seeds, and they will all have different results. Some growers will have 30% females, 70% females, 50% females and others 100% females. The sex is not exactly predetermined before the grower gets the seeds. It’s all about a few tips and tricks and most important of all, reducing stress on the plants, specifically right before the calyx’s begin to form.
Think about growing and controlling marijuana’s stress levels like that of a person with Diabetes. The less his or her blood sugar levels fluctuate, the less stress the diabetic will suffer.
If you over water or over dry your plants soil, it will cause stress, just like if your diabetics friends eats the wrong foods with too much sugar, or injects too much insulin, his body will not be stress free with all the fluctuations. They now have something called an insulin pump, that injects the proper amount of insulin 24 hours a day to keep sugar levels more stabilized throughout the day, instead of three injections per day which would have more fluctuations of the diabetics sugar levels and physical stress.
So the idea of good growing, it to try to be the insulin pump, making sure your plants:
Room temperature does not fluctuate too much
Room humidity levels do not fluctuate too much
Soil moisture levels to not become over watered or overly dry.
You keep the nutrients feeding regulated, not spiking or depleting the amounts of nutrients throughout each day. An equal ratio N,K and P will have reasonable results obtaining female plants. Remember the Diabetic pump theory,
You keep your light schedule exact, and never allow light pollution (never allow, even for a second, any amount of light to contact your plants during it’s dark cycle)
Never use 24 hours of light for vegetation, 18 on / 6 off is suitable, but not optimal. Read below for more advanced techniques.