When a marijuana plant enter the veg state, which basically means that the root system is established and they are no longer considered clones, they can be is veg for as long as you want then to be before changing to flower or bud stage.
Things to Think About
Height of Plants
You will need to decide how big you want you plant to grow, taking into consideration that the plants will continue to grow when in the flowering or bud cycle. The size of the plant will determine the size of the pot or bucket, depending on how you are growing. If you are growing hydroponically then you will want to use buckets. If you grow is soil you will want to use pots. The height will also need to be determined on how high the ceiling is, growing indoors of course. We use 5 gallon buckets and our plants grow to be about 5 to 6 feet tall at harvest.
How Long to Veg
The length of time that the plant is in veg will also depend on how tall you want them to be. When the plant is about 2/3rds the size you want them to be, then begin the bud stage.
When it comes to lighting you should use the more blue spectrum with LED lights, but really you can use the red as well. It will not hurt the plants at all. With the HID use the MD light. you can have the lights on for 24 hours if you want. We will leave the lights on for about 16 hours. A growth spurt sometimes occurs when you turn the light off for a bit. FYI 12 hours of darkness is mandatory for flowering or budding, so the light must be more than 12 hours.
Feeding and Watering
Feeding the plants nutrients and water during veg should be done twice a day, every 12 hours. You will want to gauge the nutrient amounts you use and the type of nutrients depending the stage of your plants. Here are some basics. Calcium and Magnesium helps the plants absorb nutrients. Test your PH levels to make sure they are optimal before each feeding. Watch your plants, any negative reaction to a feeding or watering will occur within a day or two act fast and adjust accordingly.
When it comes to nutrients your best bet is to buy nutrient specific to cannabis growing and that are already mixed for the veg cycle. Go to a hydroponic store to purchase your nutrient. You can learn to mix your own nutrient and it does take time and attention in doing so. We do mix our own, but it took tie for us to learn the best mixture. What ever nutrient you do use, start with half the recommended amount an work up from there. Watch your plants and look for signs of problems.
Even though we could feed the plants automatically with the hydroponic system, we have chosen to feed and water manually so that we have more control and better monitor the plants. This also helps us keep an eye out for pests. Look for spider mites and gnats. To combat gnats you can buy a natural organic spray and use sticky paper. Same with spider mites use an organic natural pesticide. Also, use diatomaceous earth as a natural pest control. It is a powder that you can sprinkle on the the plants and all over the room to kill pests. Works great and does not damage the plant at all. Highly recommend it.
Temperatures and Humidity
Keep the temps between 70 and 80 degrees and the humidity levels around 30. Too much humidity can promote fungus growth. 40% is considered high. Keep air circulating with fans and exhausts. Make sure to use carbon filters to make the odor that will begin to form as they grow, from being too much that neighbors can smell it.
This is some very basic information for you to start with in figuring out how you should move forward into the veg cycle. Every area is different in climate, water quality and nutrient. So do lots of research on the best approach for your plants.