0 items - $0.00
  • No products in the cart.

Autoflowering Grow Guide


Autoflowering cannabis plants are pretty much the new kid on the block, only really making an appearance on the mj growing scene in the past few years. I’m aware that some of you may never have tried growing autoflowering marijuana, and thought it may be worthwhile sharing my experiences with them. This is not written as a “autoflowering grow guide” per se, but a collection of thoughts and tips that hopefully will encourage some of you to give these a try.

There is a developing niche user-group for autos. There are excellent forums devoted just to their use (see www.autoflower.net and any posts by the knowledgeable Muddy) and some great seed-banks who are building extra reputation by expanding their ranges of autoflowering seeds for sale. Personally I’ve been playing with autos now for nearly 2 years. I’ve grown approximately 15 different strains both indoors and out. This is partly the result of never being able to say “no” to the thought “its only 7€ I’ll just pop that one in amoungst the tomatoes” and lately because I am in the process of developing 3 different strains myself (and that’s another article altogether).

Want to buy our favorite autoflowers?


And yet, despite having now grown more than 300 of these from seed, I still have very mixed feelings about autoflowers. Certainly the journey thus far has not been a smooth one and at times its felt like I’m banging my head against a brick wall. Almost all autoflowering seeds are described as being between 7 and 10 weeks seed to harvest, and their finished heights supposedly 30cm to 1m. I’ve experienced yields ranging from 5 grams a plant (“lowbolt” from sagramantha seeds, at 13cm) to one “cream caramel” (sweet seeds) which gave an astounding 105g after an equally astounding 126 days (that’s 18 weeks not 8!). With such a mixed range of development time, yield and growth its not surprising that when it comes to autoflowers, growing can be a difficult experience.


As we all know, cannabis is a photo-period plant: ie it’s flowering hormones are triggered by changes in the light/dark cycle. Thus you can stimulate a 2 week old cutting to begin flowering by giving it 12 hours of darkness, yet a 4 month old plant grown outside will remain in vegetative growth until mid-summer has passed.

Autoflowers are a different breed altogether (quite literally!) and will flower according to the age of the plant rather than the light/dark cycle. This development has been obtained by crossing a ruderelis strain with a standard photo period plant. Unfortunately ruderelis is fairly weak in the desired thc levels so the first autoflower strain developers had to stabilise two dominant traits: the high thc level provided by the photo-period parent and the all important auto gene from the ruderelis strain. As you can expect, early attempts were generally disappointing, and as little as four years ago autos were viewed as unreliable with poor yields and low thc levels. Most sensible growers put them down as gimmicks for newbies.

Today if you see an autoflower seed for sale you can be (reasonably) assured that its THC content will be as advertised, and its auto gene stabilised.



Now this is the big question. Most breeders claim 7-9 weeks, with some even boasting seed to harvest in less. It would be fantastic if one could get 50g per plant after just 39 days, but lets face it, its totally unrealistic. A plant doesn’t grow any faster for having an auto gene, and the dwarf autos that will harvest in ultra quick times are just that: dwarfs and thus yield is limited by size.

Of the 15 or so different commercial strains I have tried, not one of any consequence finished in less than eleven weeks – and the best ones can take anything between 3 and 5 months. If you think about it, this is not surprising: most standard autos start showing their sex at around 21 -28 days (super autos not included) – if you add on a flowering time of 8 weeks (average flowering time for a indica) then you would be looking at 11 – 12 weeks.



I think this section is the do or die between having a great auto crop or a disaster. Autoflowers have such a short vegetative growth period and the final plant is rarely very big. Get it wrong and you’ll end up with a lollipop stick of bud. That’s why I think that whilst autos fulfil a gap in the outdoor growers repertoire (after all its damnedably difficult to control the light/dark cycle of the sun), if you can its best to start them off indoors under lights. You just maximise the level of control that way.



Once you pop ’em you can’t stop ’em”

Effectively this means that whilst the answer is “yes”, the autos have a genetically limited life: from the moment the cannabis seed germinates it will progress through its short vegetative stage and speed onto flowering. As the “mother” plant won’t be big enough to take a clone until she is around 5 weeks old, once you have added a week whilst the clone roots, the clone thinks of itself as 6 weeks old and upward vegetative growth will have finished. Despite being tiny, the cutting will finish flowering at the same time as the mother more or less – here’s one I tried for a laugh:


guide to autoflowers


Start off with a little veg feed at around week 2 and slowly increase the amount of feed as the plant develops up to (depending on the auto) around week 6 or even 7. Wait to switch to flower food until after the cannabis plant has noticeably stopped its upward growth, even though she may have been flowering for a week or so beforehand.



You can grow autos on 24/0 but I think its good to let them have a little rest time and electric consumption is also a issue. I grow mine for the first two weeks under a 120 watt draw Fero LED for the first couple of weeks and I tend to keep that on for 21/3 with the LED grow light around 70 -80 cm away from the seedlings. When then they are potted on to the 13 cm sexing pots and put under my larger LEDs I then change the lighting schedule to 18/6 where it will remain until I crop.



Yes you can but it needs to be in the very early stages as it holds the plant back in that critical time. I’ve experimented over several crops with this and my advice would be that you are better off not pruning autoflowering marijuana as in most cases the plant will end up giving less weight. That said, you can break the apical dominance and encourage vigorous side branching by “knuckling” if you are using a longer term variety such as the “Cream Caramel” (yes Sweet Seeds, I know you say this is an 8-weeker, but every one I’ve grown has gone to 12 weeks plus).



Lets assume your environmentals are all good, with light at around 400watts a m2, temps at around 23ºc, humidity 55% for flowering and you are replenishing your air every couple of minutes whilst maintaining a good nutrient regime and getting plenty of O2 to the roots etc etc (who ever said growing great smoke was easy?)

The simple answer is : it depends on how long the plants are going to take. The 3-monthly varieties such as MI5 (Shortstuff) average around 40g a plant (dried weight) under my fero led lights at 10 per m2 and the longer super varieties such as Chase (15 weeks) 150g -500g a plant outdoors.



 AUTOS UNDER THE SUNgrowing autoflowers outdoors


So given all the above, why on earth would anyone bother growing this type of cannabis? Well autoflowering marijuana does have some plus points (see advantages below) but I’d argue that its main contribution to the grower’s armoury is as an outside plant. Ideally, I give them 4-6 weeks indoors under lights to maximise the vegetative growth stage without problems (mainly heat, or lack of it) then its outside with the little darlings for finishing off. And as long as your night temperatures don’t drop below 10ºC these hardy plants will put in crops quite quickly. YES, you could grow one mammoth plant yielding the magical kilo, but you’ll have to wait the full 8-9 months before you smoke (and thats assuming nothing untoward happens in the meantime), Alternatively, assuming you are blessed with plenty of sunshine, you can get crop after crop after crop in the same space and be smoking fresh bud for 9 months of the year.

There’s also the added bonus that because they are so short, they are much easier to hide than a large plant, and be camoflaged in your vegetable garden. If you want to get decent weight return, grow in blocks of ten in separate 1msq plots.





Which brings me onto:




Legal implications aside (and we always assume that every grower is acting within the laws of their respective country), the main draw back to the above is the cost of the seeds. If you are looking to get any chance of weight/area or weight/3 months, you are going to have to invest in more seeds than you would with a standard outdoor plant. As someone who was used to having a lovely mother plant who would give me free cuttings ad infinitum, I find it galling to pay such a large amount (5-7€ / seed) when planning grows needing 10 plants per m2. The 100€ spent on seeds for the 2m2 covered by the Fero 900 LED just seemed too steep a price as once you add on nutrients and boosts etc it almost seems cheaper to buy spliff than grow it (at least in my part of the world). And as the accountant in the family has pointed out, if I had had to buy every one of the 300 odd autos I’ve experimented with in the past 18 months, I’d have spent in excess of 1500€.


So therefore (having spent more money than I would have liked) I’ve followed the only sensible course of action and bred my own autoflowering seeds. The process is so easy I really have no idea why the seeds should cost so much. Yes I know the revenue probably all goes on product development, packaging and propaganda, but as I have it from reliable sources that some breeders themselves only get 60c a seed this seems a little unfair.  And it still comes back to the fact that a single photo-period feminised seed can give you several hundred grams for your 5€ but a single auto may only yield 20g.


For those of you who haven’t bred your own seeds, here’s how I do it

  1. experiment a little and find a strain you like in terms of yield, time to harvest and enjoyment of smoke. If you can, either try more than 3 of each type you try, or at least follow others’ grow-histories of the same strain and evaluate if they seem reasonably standard.
  2. Buy yourself 20 unfeminised cannabis seeds. Germinate, grow and sex in 13 cm pots.
  3. Around day 28 (or as soon as sex shows), separate males to a separate room. Any space will do: they can cope with a sunny windowsill (if that’s safe for you), or better still, in a small tent under 2 x 45 watt cfls for around two weeks. At week 5 choose 3 of the strongest smelliest males and kill the rest. After a week I eradicate two and keep only the best looking male. You read horror stories about accidental pollination, but touch wood, with a little thought (washing hands, not going straight from males to females etc) I’ve had no problems keeping my main room pollen free whilst my “dads” grew in a small video cabinet in the garage.
  4. Around weeks 5-6 its time for the love action. Now strictly speaking if you want to develop a special strain, you would only want to pollinate one branch of a selection of plants (all carefully numbered) so that come harvest, you would be able to cross reference the seeds from the plant with the highest THC, biggest yield etc. But lets face it, if you just want to collect a number of seeds for your personal use this isn’t necessary and is likely to increase the risk of accidental pollination to the rest of the mother plant. Simply pick your favourite 2 girls and make your criteria for “favourite” what you will. Obviously you aren’t going to be able to evaluate yield or smoke at this early stage in the game, but you may simply like the look of one plant more than the others (unscientific but often successful), or you may use pointers such as size of plant given the shortness of many autos. Bring the two lucky ladies into the male room, and rest the male between the pots. I think its essential to sing them a little Barry White, but the choice of lurve music is up to you :).
  5. Leave for around 4 days until you see some of the pistils turning brown then kill the male. Don’t be tempted to keep him for any reason. You may have named him, befriended him, but there’s really no further use for him. Spray the mums well with 1 teaspoon of washing up liquid to a litre of water twice over two days as this will ensure you wash away any lingering pollen. You can then take them back to the main chamber
  6. The seeds will take around 4-5 weeks to develop. Its important to let the seeds mature properly on the plant, and then to “prove” in a safe and dry atmosphere afterwards for 2-3 months. Ideally you need your seeds to be the distinctive tiger-striped brown for best rates of germination. But by sacrificing two of ten females, you will easily collect 400-600 viable seeds which should keep you going for a month or two (!)

It used to be at this point that I added a link to buy my own seeds: however these have been so popular that several seed runs have all sold out. So I’ve hooked up with one of the big Dutch seed breeders in order to be able to offer you loose feminised seeds direct from them (via kannaponica.com) .. these are at amazing prices so winners all round 🙂

Learn more






  • Despite the drawbacks, I love the fact that I can grow so many different varieties for different highs. I swop from a heady smoke one week to a buzzy one the next. The surprise element of a new strain adds a certain frisson to the smoking experience (and also the cultivation).
  • There is no need to differentiate between grow and flower rooms. This is especially useful if you want to set up a multi-crop system where you harvest every few weeks. There is no need to lightproof your vegetative and flowering areas as leakages of light are not going to effect your marijuana flowering.
  • You can also start up multi-crop systems outdoors in a small space in the garden.
  • If you suffer frequent power outs, its not going to damage the harvest.
  • This isn’t scientifically tested, but it seems to me that the mongrel ruderelis element adds a touch of hardiness to the plant. They certainly seem to have coped better with problems such as cold than my standard photo-period plants did.
  • Autoflowers are great if you have height restrictions, either within an indoor grow room or to hide them outdoors.
  • If all your growing friends do so outdoors, its great to be smoking whilst they’re still waiting to go into flower! (and makes you very popular too)




  • More electricity for the same amount of bud as photo-period plant grown indoors. Yes I know I could in theory reduce the light hours from 18 (or even 24) down to 12, but if you knew your plant would continue to produce bud with a third more light would you reduce its hours?
  • The lack of uniformity in size and maturation rates even within the same strain. Quite frankly I think its impossible to grow these on trays hydroponicaly as I often have to adjust the heights of pots to get an even coverage of light. Also I usually have to harvest in two to three stages as the different genos within the breed very often mature at different rates. Yet another plus to growing in coco and perlite!
  • I don’t know why it is – presumably the ruderelis – but they just don’t seem to be as pungent as many photo-period plants. However, the smoke itself is as strong, its just not so stinky!




About campo cultivator

Can't seem to stop trying out new ways of growing! Likes nothing better than a test grow or comparison and truly finds growing itself almost more enjoyable than the end result :)

View all posts by

Related Items
  • Nicely done, thanks for the info!

  • Great Info !!!

  • thanks for the advice!

  • Most amazing site for all information needed, within a matter of minutes i have knowledge that would have taken me hours to google! Awesome site with the live chat will be comming back lots for questions!

  • Could you convert your Godless measurements to standard one’s? metric is of the Devil thank you p.s.super great info.really helpful!

  • I have to throw out my 6 wk. old auto bubblelicous plant that is covered in flowers and bud sites because it ‘s 5ft/3in.tall and growing (6 1/2ft from bottom of pot to top of plant) I have 2 in. of space left i’m very sad and disappointed.this was my first grow maybe my thumb is too green.it should be 2ft.tall max.

  • I cut 6 in. off the top of my 10 week old auto bubblelicious plant 3wks. ago due to ht. 6ft/10in. the cut site stopped growing but the 3 nearest branches zoomed past the cut spot and now are three 6in. bud clusters the plant is loaded with bud clusters even at the bottom the bud and surgar leaves are healthy and look great but 80% of my fan leaves have turned yellow and died or are dying my bud pistils are about 55% red should I be concerned about my fan leaves thank you p.s. first time grower

  • Terry, I think your plant is ready to harvest if the trichomes are 50 % amber. Th leaf yellowing is natural, just shop her off!

  • Hi Terry
    Well many people don’t advise pruning autoflowers although I main stem tip prune mine (which is what you have done) normally around week 2-3 as I find it encourages branching and better buds.

    Re the fan leaves yellowing: these will yellow as plant matures BUT if 80% of your leaves are going yellow it suggests there is a problem, most likely reasons are:
    Lack of nutrients due to a PH imbalance
    Possibly even light bleaching (although leaves tend to look pale rather than yellow)

    Have a look at these and if there are still problems, let me know


    PS love your comment about the pet chicken, I often feel the same myself, I had some super stinkys that were with me for nearly 6 months, I had thought about naming them and writing out the adoption papers .. the only answer is to have your next baby ready to go so you’re impatient to make the space for her 🙂

    • Hey Campo, thanks 4 the great info. my soil ph is 6.7 and the leaf loss is now at 95% at the same time i’m growing new leaves and flowers at the bottom of the plant perhaps because I have a 2nd light hanging over my 2 week old plant that is providing it with extra light at the bottom also I look at my buds with a lighted jewelers glass and they are dripping with what looks like crushed diamonds and course sugar I think I will harvest in about a week thanks again.

  • I planted my seeds straight in the soil and did not germinate it’s been 4-5 days and no sprouts yet, did I screw up. Should I germinate and start over, I used auto flowering seeds.

  • When you flush the plant do you place it under light or complete darkness until done flushing?

  • Just about to start flushing my think different auto how long should I flush for b4 chopping??

    • Hey Graham
      lol a bit of a tardy response apologies
      Generally I like to flush for around ten days if possible until I see the plant start to eat itself meaning its taken colour from the leaves cannibalizing itself as such

  • Ive planted 4 autoflowering seeds in 4 pots in 1 pot ive 3 growing in another 2 growing and 2 bad boys anyone no wats going on this is my 3rd time growing never seen it before or heard of it any help im 5 weeks in but looking good

  • Hey, what brand of mutes do you finds it best to use. I’ve only every used Dutch pro products??

    • weed widow says:

      hi there – well the ones i’ve tended to use (and liked) are General Hydro Flora series and Canna (but you really DO need the Canna Boost) – we have customers who swear by House & Garden as well

  • You mention “super autos aside” in reference to the auto flowering plants taking 21-28days to show their sex. how many days do the super autos take to show there sex and what are your favorite strains of super autos?

  • Hey Zac – when this was written a few years ago, the superautos were a new breed of autoflowering cannabis, & there were only a few of these super strains around. Chaze was one of my favorites (Short Stuff seeds). They took / take anything up to 2-3 months before showing sex (the Super Stinky especially took 5 months nearly to go seed to harvest! but gave a whopping 300g per plant).

    Since then there were are a lot of “semi” super autos around. This year we grew Dinafems new XXL Auto range – these are 12 weeks and were a good 3-4 foot tall, sexing around 1 month. Can’t say end result as unfortunately the local police confiscated them but I have to say they looked outstanding up until week 4 (when they were taken)

  • Hi im a first time grower and have just purchased auto flowering seeds can you tell me if i just put the seed straight into pot in my set up and give 1mm of feed? Thanks

  • Dinafem
    Seeds every time all females never males the chinaman

  • Dlnafem females every time never a male the chinaman

  • Hi im on my first grow with autoflowering plants they are 6 weeks old and have been under light 24/7 would they benifit under 20/4 lighting cheers in avance

  • auto white widow from pyramid seeds
    Shown first pistil at day 28 and growing healthy and big but no real bloom or flowering almost day 70 reaching but looks like day 70 healthy plant many branches and one thick stalk plz help

  • hello,i’am a first time grower i have loved plants all my life (born with a green thumb) your info is an inspiration. my tail is waggin. i think i love you. i will write back in ten weeks with news about my auto blue amnesia. she came to life on 1-19-2015, proud dad its a girl. POWER TO THE PEOPLE

    • Hey cheers for such a nice comment! Send us pics of your girl when she’s done ([email protected]) and we’ll post them on the site. I’m a big fan of amo strains but have never tried the blue amnesia … Seems to me you’re going to enjoy growing as much as I do!

  • Can you grown cannabis plants like an ordinary plant without all the lighting, feeding, etc?

    I understand there won’t be a massive yield, but is it worth trying to grow a cannabis plant indoors in a pot, just water it every couple of days and do nothing else, then when it’s grown enough, harvest it, cure it, then smoke it!?!?

  • hi guys newbe here on my first auto grow think it’s going ok but iv started to get new leaves grow from my first true leaves after other growth elsewhere is this normal and is it a good sign? many thanks guys

  • Hey guys, i’m on my second grow now, and my first auto batch, I got some fast & vast auto (heavyweight seeds) from jungle seeds, originally they were gonna be grown out doors but my partner was a bit too excitable and decided to take the lead with it unfortunately the winter has set in now so I’ve had to move what I can inside, so I’ve got 7 left out of 27, really not happy about this but I guess that’s people sometimes haha, but yeah so they are around 9 weeks old now and have had a bit of a a slow start with the weather conditions but they’ve been in my cupboard for about 2 and a half weeks now, it’s amazing how fast they grow, when I put them inside they were only about 2 or 3 inches tall topos but now they’re getting on for a foot high now, i’m so excited 🙂

  • I need some help. I can’t get my autos to finish I use plenty of light feed them right. Temp is good but still cola doesn’t for tight. I have grown 7 foot plants inside hydro. Could you maybe tell what I’m doing wrong.

  • Autos are amazing, all the issues you describe I have not seen come to fruition. I am averaging close to a pound per plant dry weight. And the seed to harvest times are almost spot on.

Leave a reply