For really long flowering Sativas you can also start then on 12/12. Then as thy get closer to the end switch to 11/13. Sativas at the equator typically get 12/12 year round. The longest day at the equator is 12 hours 7 minutes and 15 seconds. So for all practical purposes everyday at the equator has a 12/12 cycle. And for sativas to do their best indoors they need to be blasted with light. Equador in the Andes has some of the highest UVA/B levels of light on earth. At 20,000 feet UVA/B has been measured to be as high as it is on Mars. Not saying anything grows at 20,000 feet, but it shows you light levels are extremely strong at the equator, and at altitude. Equador also has extremely high light levels, and UVA/B on the beaches at sea level. You will fry to a crisp in most places in south america near the equator at both sea level, and at altitude. And with high light level, you also much have tremendous fresh air exchange if growing inside.
Regardless of Indica, or Sativa, I start all my seedlings under 1000w Hortilux HPS. In Nepal in the Himalayas they also have extreme UVA/B light levels. I use 2 x 32w Solacure UVA/B bulbs for each 4 x 4 and 1000w Hortilux HPS. I use them also for seedlings. They are on for 4- 5 hours a day at around 24 inches height, and less when plants are bigger. I start seedlings at 24 inches from the HPS-Solacure bulbs, and let the plants grow towards the bulbs. When/If they show leaf stress I will slightly raise the lights, but usually if air exchange is really good, I have no problems. Air temps reach 85f at the hottest, with fans blowing 24/7, with enough wind to make all the branches have a slight breeze. I dont pummel them. No wind burn. But I do have a constant fresh air exchange. Not just room exchange. Fresh outside air. I also dont grow in a tent. I have a 20 x 20 room for flowering, and a 15 x 15 room for veg though I dont use nearly all of it. I generally use 3 x 1000w HID in a 12 x 4 area for flowering, and a 4 x 8 area and 2 x 1000w HID for veg. 10 foot ceilings. In the winter I use a 1150w Gavita HPS, and ke the Solacure bulbs on 8 hours a day at 36-40 inches height from canopy. You cant get the Gavitas closer than 36 inches, or the infrared will fry them. Gavita 1150w has tremendous infrared. I used to wonder why all the videos, and photos I saw had the Gavitas so far away. Now I know. Heat, and infrared. The Gavita is probably 20% hotter than a 1000w Hortilux HPS, but also covers a 4 x 6 at 36 inches vs a 4 x 4 with the Hortilux.
I have a 2006 cut of Willie Nelson thats done in about 105 days, and is my main pure sativa. Its wickedly potent, and has an extreme yield. Best pure Sativa Ive seen. Its a cross of Highland Nepali, and Vietnam Black. I wish Reeferman would bring the strain back so I could get some males. My buddy originally went through 50 females and picked this one. They can take up a huge area, and I bend mine over and let it grow like a bush vs letting it grow vertically. It gets way to big, and will grow into the lights. when it starts flowering, it will stretch for 80 days. It can stretch up to 5-6 times it height when flowering starts. If you veg it to 1 foot, it will end up 6ft tall, or long if given enough light. The first time I ever grew it, I vegged, and for 30 days in 5 gallons of Promix BX, and it grew so big in flowering it took up 2x 1000w HID when bent over. It covered about a 7 foot horizontal distance when bent over, and produced 16 ounces. Ive never seen any strain in 45 years other than this one produce 16oz out of 5 gallons of soil. Also in my neck of the woods I cant grow it outside because it wont finish until late november, which is way past the freezing date. I have no doubt if I could grow it outside, and give it a whole bale of Promix BX it would produce at least 5-7lbs. Maybe more, and would be 18 feet tall. Which would most probably be found by the national Guard as Im also in the most unfriendly of states. While Ive also never topped this strain, Im sure it would take really good to topping as it grows fast as hell, and is extremely branchy. Willie Nelson is my favorite pure 100% Sativa strain. It tastes like Lemon Grass, and has lung busting smoke expansion. It tastes like lemon floral honeysuckle hash, and pepper when exhaled. The buds are medium dense for how big they can get, and the colas are huge. As big or bigger than a 2 litre bottle. It doesnt have a really strong odor when growing. It makes alot of people paranoid, an also gives terrible cotton mouth, and red eyes. It has a really racy head high, and a hard comedown. High lasts for hours and hours.
This isnt my bud, but will give you an idea of how big they can get. Like I said, I wish they would bring this strain back.