KOS – Black Forrest



  • NAME: Black Forrest F2 (bx1)
  • GROWING/BREEDING STYLE: True Living Organics (TLO)
  • LINEAGE: Cherry Bomb x Vietnamese Black Jungle Sativa 
  • YIELD/SIZE: Large
  • FLOWERING TIME INDOORS: 16 Weeks, Give or Take 1 Week per Individual Females
  • SMELLS: Acrid, Nag Champa Incense, Black Licorice, and Cat Piss/Honey Oil, One-of-a-Kind Smells and Flavors
  • FLAVORS: Same as Smells, Very Highly Exotic Smoke—Literally, One-of-a-Kind Terpene Profile
  • STRETCH: 2x to 3x
  • PHOTOPERIODS: Sprouting 16/8 (or 12/12 for first 14 days), Veg 18/6, Flowering 12/12 
  • SATIVA/INDICA/RUDI RATIOS: About 95/5 Sativa/Indica 
  • HARVEST OUTDOORS: 2nd Half of December – Northern Hemisphere 
  • BREEDING STYLE: Regular Seeds – Using Real Males


Let me first explain to you the F2/bx1 descriptor on this variety. The original Black Forrest was a straight up F1 hybrid, as you can read about below in more detail, but I made the original Black Forrest F1 almost 30 years ago. I germinated some a while back, and at the same time I germinated 4 of my 6 remaining Vietnam Black landrace jungle sativa seeds. I found a stellar female Black Forrest (BF) female—yowza, and, as luck would have it, 2 of my 4 Vietnam Black (VB) seeds sprouted. One of the VB sprouts was pretty weak out of the gate, as these VB seeds are more like 45 years old and were sent to me by my cousin who lives in Vietnam over 3 decades ago. But the one VB that remained was wicked strong and hearty and turned out to be a true stellar male.

So, this Black Forrest F2/bx1 is a “soft” backcross back to the landrace VB line. A hard backcross would be back to the original female/male VB individual that was an original P1 breeder. A hard backcross I label as Bx, a soft one I label as bx. The Black Forrest original F1 hybrid was my F3 Cherry Bomb (male) x VB. This version really leverages the wild side of cannabis with an insane potency, seriously edgy and full of energy.

If you do not have actual skills indoors, or growing in containers period, with running real deal landrace type sativas, my advice to you would be start flowering these much smaller than you would think. If you are familiar with growing wild-child sativas in containers, this one is an alfa strain indeed and can sustain ridiculous growth rates when happy—ridiculous! Outdoors in the right environment she will definitely get way off the chain and can easily get MUCH larger than you anticipated.

Even if you aren’t skilled enough yet to feel comfy growing these, just keep them sealed up light and air tight in your refrigerator and they will stay 80% viable for at least 20 years. Once you get your sativa container growing skills dialed in a bit you can break her out and experience the WoW! 


  • Male Breeder(s) Deets: 1 superior male of Vietnam Black jungle landrace sativa was the paternal P1 in this cross. These seeds are about 40 years old, I planted 4 seeds and ended up with one insanely hearty awesome and healthy true male, with extremely high resin production potential, per its offspring. Noice!
  • Female Breeder(s) Deets: 1 Black Forrest female (crazy terpenes and resin production with beefy floral formation) was the maternal P1 in this cross. Uber high vigor and heartiness.

Additional Considerations

If you pull this one off for the 16-week flowering time well, you will NEVER forget it. The potency is not only over the top, but it has this very unique edgy energy heavy facet. If you had to take her at, say 14 weeks, you would still have a fairly ass kicking sativa, but that last 2-weeks of the 16-week flowering time would take that potency way-way up. Not only will she utterly bake your ass, but the length of those effects (legs) will be several hours at least—she’s like a freight train—and she’ll take up to 20 minutes to set-in after smoking.

As breeding stock these are sublime, and truly chalked full of highly adaptive survivor genetic expressions. The terpenes are literally one of a kind in my experience, nothing else smells or tastes like Vietnamese Jungle Sativa baybee.

Growing Instructions

I would highly recommend you sprout these under a 12/12 photoperiod. Keep them under this photoperiod for their first 14 to 15 days above ground before moving to a vegetative photoperiod. This will allow you to sex them easily at the 30 days above ground point. In containers, I would HIGHLY recommend you flower clones, and not seedling plants.

You should start these flowering shorter/smaller than you think you should, if these are happy plants the growth rates will blow your mind. I start them flowering under 400-watt lights at about 9 inches tall, topped to 4 or 6 mains. They finish up very close to 3 feet at harvest time. I would not recommend transplanting these once flowering has begun. Get them into their flowering containers about a week before flowering begins. If you transplant them once they have started resin production, the big available nitrogen boost of all the fresh new soil could easily cause these plants to put on some additional vegetative growth. That will, sadly, cause resin production to take a hit.

You can’t really throw anything at these they can’t handle, as far as environment goes. They are pure tough, Tonka tough. Outdoors she doesn’t care about rain, or heat, and only severe cold will get her down. What she will not like is powerful feeding that alters her soil pH drastically. Like from using liquid nutrients or special additives.

Please do not sprout these on a 24/0 photoperiod and KOS recommends 16/8 for sprouting and until 30 days old. Then switch to 18/6. Alternately…

Using a flowering photoperiod of 12/12 on these sprouts for their first 14 days above ground, then switching them to an 18/6 photoperiod will allow you to easily sex them at 30 days of age—give or take 3 days.

Always allow plants to get at least 55 days old from sprouting, before starting to flower for maximum resin production. Plants grown from seed work much better outdoors in the ground than clones do. Alternately, clones work much better in containers than plants from seeds do. Sprout seeds in ambient temps of 75 – 85 deg. F. Obviously KOS always recommends organically growing our gear in living soil for the full appreciation of smells and flavors, among many other reasons—cheers!

BREEDER’S NOTE 10/7/22: Here’s what I would do if I were you, and you are even a little bity unsure you can pull these off.

  1. Make sure you allow these sprouts to mature before flowering. This is one of the big reasons you want to flower clones in container growing. These plants root very easily and quickly. I would always want these plants to be at least 60 days old from sprouting before starting flowering.
  2. Start them flowering smaller than you think they should be. Under 400-watt lights I would say 9-inches, under 1,000-watt lights 1-foot.
  3. Top them down to 4 to 6 mains for the best yield per plant value.
  4. I have never seen a bad female that was healthy. Resin production is fairly locked in and it is immense.
  5. You may want to put these seeds away in the fridge and make a practice run with another sativa first that is around 12 to 14 weeks flowering, to make sure you have your program dialed in for the long flowering. Do not transplant these plants once they are more than 1 week into flowering.


Additional information

Weight 1 g
Pack Size