How to harvest cannabis in 80 days


In the spring of 2015 we received a proposal for an experiment: to plant six auto-flowering strains into soil, in two previously fertilised outdoor plots, and to grow them without adding liquid fertilisers, but exclusively with the nutrients residing in the substrate. This is what the outcome was. 

We intended to test several auto-flowering genetics produced by Dinafem. They had been positively described to us and it had been long since we had last grown a batch of auto-flowering plants. From 2008 – when we sowed a few Lowryder specimens, i.e. the first auto-flowering seeds among the latest to be developed – to date we have harvested plants with this genetics several times. Make no mistake, the results were time after time better and better; the current varieties are bigger, more productive and more potent than the earlier ones. Indeed, the quality of genetics has improved much in the recent years and we wanted to test the extent to which plants could thrive when grown in the soil, in an outdoor environment and with little care.

The evolution of self-flowering genetics

All auto-flowering plants contain the genes of Cannabis Ruderalis, a self-flowering cannabis species that grows wild in Eastern Europe, Russia, China and other places of Central and Northern Asia. Genetically, the wild Ruderalis is normally rich in CBD and poor in THC, meaning that it is not psychoactive. Its automatic flowering is a very interesting feature, whose potential has long been known. Rob C. Clarke already said, in a paper titled Marijuana Botany of 1981, that Ruderalis could be useful in the breeding of fast-maturing strains for commercial use in temperate climates.

The first psychoactive hybrids of Ruderalis were put onto the market a few decades ago by Sensi Seeds, in the Ruderalis Indica and Ruderalis Skunk strains, which remained the only Ruderalis crossbreeds available for many years. Ruderalis Indica mostly generates small auto-flowering plants, but their psychoactivity is relatively low. Ruderalis Skunk, instead, is more potent but, similarly to Ruderalis Indica, only half the quantity of plants are auto-flowering, while the lifecycle of the other half normally ends in September or October. These strains have not become much popular, although they are still featured in the catalogue of Sensi Seeds, for any consumers wishing to taste it.

The current enthusiasm for automatic strains started about a decade ago with the introduction of Lowryder marked by The Joint Doctor seed bank. The first Lowryder specimens were revolutionary as they were really all auto-flowering and ready in only nine weeks, as the catalogue promised. Lowryder was a stable and homogeneous strain that was harvested at 60 days from germination, generated short plants having little productivity and low potency, but all blooming automatically irrespective of their photoperiod.

Lowryder plants resembled small Indicas in their appearance, with a main branch and a few small secondary branches. The final size usually varied between twenty-five and fifty centimetres, depending on the applied tillage technique, average temperature and light quantity and intensity. Yield could also vary significantly, depending on the technique, from three to four grams produced by a plant grown in winter close to a window, up to thirty or more produced by a plant grown in the best conditions. In any case, it was barely productive compared to non-auto-flowering strains. The current auto-flowering plants are definitively better yielding.

The major qualities of Lowryder, its potency, auto-flowering genetics, maturation rapidity (i.e. only sixty days from germination to harvest), stability and homogeneity were not exploited for production, it was rather an ideal plant for crossbreeds. This is the main reason why virtually all current auto-flowering strains derive from Lowryder. The breeders of various seed banks used this strain to introduce the self-flowering gene into their creations. They bred hybrids between Lowryder and their favourite genetics, which in turn were later selected and crossbred again, until the new strains were stabilised and all plants became auto-flowering. This process is long and requires several crossings before homogeneous and stable genetics can be obtained. In addition, as auto-flowering plants cannot permanently be retained in the vegetative stage, which is on the other hand possible with strains having a blooming stage that depends on the photoperiod, it is impossible to keep the original parents (the male and the female that were used to create the strain) to reproduce the crossbreed and generate new seeds. Auto-flowering strains are permanently evolving; for each generation of seeds, breeders start from the previous generation, make new selections of males and females and cross them between each other, or with a new strain, to bring in new psychoactivity and vigour. The downside of this system is that the same strain cannot be perfectly reproduced and each generation is slightly different from the previous. Its upside is that a strain never reaches a final stage of development, but rather improves year after year, if the breeder makes a good job.

In later years we sowed again auto-flowering strains and, in general, noticed an increase in height, yield and potency as well as a longer blooming period. If Lowryder was ready in sixty days, many of the best strains currently available require between 75 and 90 to complete a cycle, i.e. two to four weeks longer. Logically, they produce more, as they have extra time to grow and bloom.

Plots used for plant growing

The first crop was grown in the garden of a cottage, which included a small plot that measured about 2 x 5 m and was surrounded by a metal fence covered with mesh to avoid prying eyes. It faced south and was exposed to the sun almost the full day, although the fence provided shade to plants in the early morning and late afternoon/evening. The soil was fertile and contained enough organic matter, as the grower normally deposited here the soil he had previously used in flowerpots. Two or three months before sowing, the soil was covered with plenty of compost, poultry manure, and horse/goat dung. It was then irrigated and put to rest for various weeks for the organic material to decompose and mix with the substrate. Before transplanting seedlings, a power tiller was used to plough the soil and make it looser and free of clumps.

The second cropped area was a guerrilla plot situated in a valley and surrounded by a wide bramble wall measuring more than two metres in height, which kept it completely away from prying eyes. It could only be accessed through a small tunnel through brambles, which required any person wishing to enter to crawl in. The grower had installed an irrigation system, and water was conveyed to plants by an underground pipe, which obviated the need to irrigate plants manually. The soil was very sandy and did not contain much organic matter or nutrients, similarly to the first plot. About six weeks before transplanting the seedlings, the soil was fertilised with dung and poultry manure, but in a lower quantity than in the other plot. Plants were exposed to the sun approximately from ten in the morning to seven in the evening.


The six selected auto-flowering strains were Blue Amnesia XXL Auto, Critical+ 2.0 Auto, Moby Dick XXL Auto, OG Kush Auto, Sour Diesel Auto and White Widow XXL Auto, all marketed by the Dinafem seed bank. It is also worth adding that these seeds were bought in a grow shop – we deliberately avoided sourcing them directly from Dinafem, and they were not even informed that the seeds were meant for a test crop. What we wanted to do was test seeds normally sold to consumers and assess them without any distortion. If we had asked them to source them directly from their seed bank, and they had consequently known that the seeds would be used for a test, perhaps they would have given us the freshest and the best they had. Instead, we wanted to carry out our test as objectively as possible and purchased the test seeds, out of our own pockets, from the same place where they are normally sold to growers.

Seeds were germinated on 8 April in small flowerpots filled with the Light Mix Speedy substrate. The seeds had a good aspect. All were dark coloured and none were hollow or broken. Undoubtedly, they were fresh and had been harvested quite ripe, i.e. out of thirty seeds (five for each of the six strains) all germinated except a Moby Dick XXL Auto, which meant that the germination rate was excellent.

Normally auto-flowering strains develop so rapidly that it is theoretically better not to transplant them. Transplanting always causes a certain shock, which for a few days prevents plants from further growing. If plants are grown in pots, it is better to germinate them directly in the final pots. However, for the seeds to develop in the soil, growers have to face a dilemma, if they sowed them directly, they would run the risk that the newly sprouted seedlings could be eaten by snails or other pests or killed by bad weather; if, on the other hand, they sowed them into pots, then they would need to transplant them. In the case under review, the choice was made to plant them into pots, to avoid the same experience as that of the previous year, when they had directly been germinated in the soil and a torrential rain had swamped away a large quantity of seedlings.


Plants remained four weeks in pots on a very sunny balcony. The original idea was to transplant them into soil at week 2 but, for the low temperature that persisted several nights and a few cloudy days, in the first fifteen days their growth was not so rapid as it could have been with a milder weather and it was decided to wait an extra two weeks for the plants and, more importantly, the root system to develop a bit more. Generally, if plants are transplanted before the root system grows to a sufficient level – so that the full bunch of roots can be removed altogether – it is very easy to break up a few roots and the transplant shock would be higher.

Plants were transplanted into soil on 7 May at a height of 15 to 25 cm. The two largest and healthiest plants of each strain were planted in the garden, where they would ‘enjoy a better treatment’, while the remaining three of each genetics were taken to the guerrilla plot. Channels were dug around each seedling to retain the irrigation water and tags were applied to stems with the name of each strain. Many growers tend to rely on their memory to identify plants, but experience shows that, by harvest time, especially when several strains have been sown, growers cannot easily identify which strain was planted in a given location.

After transplant, snail and slug baits were spread onto the soil to prevent the young seedlings from being attacked by these pests, which could be particularly harmful when stems are soft.


The garden crop was watered every two to three days, depending on the weather and how dry the earth looked. No extra liquid or solid fertilisers were added and plants were only fed by nutrients residing in the soil. The fertile and loose earth of the garden eased the development of a good root system, which soon accelerated the growth of plants. The weeds that grew around plants were uprooted at weeks two, four and six from the date when plants started growing in this plot.

The guerrilla crop was watered every three days and was only visited every ten days to prevent people from snooping into the grower’s affairs. The more frequently growers visit a guerrilla crop the more likely they are to be discovered, as an observer would more easily see them sneaking through brambles, and therefore find a way in. For this very reason, it is advisable to access the crop every day through a different path, to avoid leaving any traces.

The plants grown in the guerrilla plot were slower developers and grew to lower heights than those planted in the garden. Given the infrequent visits to the crop and the low weed control, weeds grew much higher, i.e. to such a level that they competed with cannabis plants. This unfavourable condition, combined with the reduced sun exposure and the sandy state of the substrate, which excessively drained water and barely retained humidity and nutrients, contributed to a lower output.

Light and productivity

The productivity of auto-flowering plants is mainly determined by the quantity and intensity of the light they receive. The best results can be obtained when plants grow in an indoor environment, under a powerful sodium lamp lighting them intensely for twenty hours a day, with the same lighting cycle every day. In Spain, in an outdoor crop, the hours of sunshine do not exceed fourteen to fifteen hours a day, even in June or July, and light in the early morning or late evening is not as intense as at midday. In cloudy or rainy days, plants can even receive less lumens.

Indoors, with a photoperiod of twenty hours of light and four hours of darkness, plants receive, in a lifecycle of eighty days, as many as 1,600 hours of light. Outdoors, although they are grown between the 10th of May and the 30th of July (i.e. the sunniest eighty days of the year), without a single cloudy day and in an area where they are exposed to sun from sunrise to sunset, they will receive no more than 1,100 hours of sunshine, or 30% less than in an indoor environment.


A few days after transplanting plants into the soil, the first female flowers started to appear. As all were feminised seeds, neither males nor hermaphrodites were born. In the beginning, flowers were very sparse and plants continued growing vigorously.

At week seven of their lifecycle, i.e. three days after transplant, the plants in the garden already measured between fifty and eighty centimetres in height. Of the six, Moby Dick XXL Auto and White Widow XXL Auto were the tallest (they also ended up being the most productive) and had many side branches. A Sour Diesel Auto grew quite well, while the others lost the central shoot (which had possibly been bitten by a bug) and remained short. Critical + 2.0 Auto was somewhat short but compact, leafy, and with enough branches. Blue Amnesia XXL Auto specimens were just a little underdeveloped, a bit short but also well branched out. OG Kush Auto was the worst off, several specimens presented some type of mutation that had caused leaves to shrink, and plants had grown high but without much branches. Guerrilla plants were much shorter, between 20 and 60 cm, but even the tallest had much less branches. They were visibly underdeveloped.

At week eight they continued growing and branching out. The tallest had reached 1 m and buds were increasingly rich. In general, plants had generated many more side branches than the first auto-flowering strains.

At week five of growing in the soil (or nine after germination), they had already reached their maximum size and buds started to be full, although they looked fairly aerated. Flowers ware already fully covered with resin, but all stigmas were still white. The shortest were Critical + 2.0 Auto, which in the end measured 60 to 80 cm in height, although with several branches extending from the central stem.

All plants were harvested on the same day, the 27th of June, at 80 days of lifetime and 50 days after their transplant into the soil. Of these, only Critical + 2.0 auto could have been harvested a week before, the others however had reached quite an optimal stage of development to be ready for harvest.

The yield of guerrilla plants was much lower than that of plants grown in the garden, however, at harvest time they could barely outstrip the large quantity of competing weeds that had grown around them, and which were depriving them of light and nutrients. Most probably a weed control operation would have resulted in a better output, even twice as much.


In general, the autos of Dinafem left us satisfied. The three higher yielding strains were White Widow XXL Auto, Moby Dick XXL Auto and Sour Diesel Auto; except the plant that had lost the central shoot, the three strains had a similar yield of around 100 g per plant in the garden plot and between 25 and 40 g per plant in the guerrilla plot, which quantities could have doubled if they had received extra care. Blue Amnesia XXL Auto also gave a good output in the garden, with an average of more than 70 g per plant, but yield was lower in the guerrilla plot and did not exceed 23 g. Critical + 2.0 Auto only achieved 36 g on average although, for the size plants had reached, their yield was not bad at all (17 g in the guerrilla plot) making it an ideal strain for inconspicuous row crops. Lastly, OG Kush Auto, was a fairly slim and little-branched plant whose yield in the garden plot was on average similar to that of Critical + 2.0 Auto, but two times higher and with various unsightly mutant specimens.

The quality of buds of these new auto-flowering strains is now much better than that of previous strains, although all have similar aspects giving away their auto-flowering genetics; there are many leaves in the buds, and flowers do not grow so close to each other as in normal strains, although they have a definitively large quantity of resin.

These plants can be easily grown, provided that there is sufficient sunlight, a fertile substrate and frequent watering. They should not be planted very close to each other or surrounded by weeds, to avoid competition. As the growing and blooming stages overlap for several weeks, it is important for plants to receive early fertilisation at the beginning of flowering (i.e. a combination of nitrogen, phosphorus and potassium) and well until full bloom. If nitrogen is removed too early, the plants will remain small.

From what we have seen, the higher yielding and qualitatively better autos were those that grew bigger and took up to 75 to 80 days to bloom. Smaller strains were quicker but also yielded much less and had less potency and a poorer psychoactive effect. The best way of achieving a good harvest in the shortest time possible is to plant together many plants with rapid genetics (up to nine per square metre, with their seeds sown in the soil), their numbers will set off their low yield per plant. The problem is that auto seeds are expensive and not all growers can afford eight euros per seed, especially if they have to sow them in large quantities.

The size of pots is also important. Small strains develop well in pots of ten litres, but the large ones require at least fifteen to twenty litres of substrate to achieve their highest potential.

Outdoors even auto-flowering plants with a longer lifecycle are much quicker than non-auto-flowering strains. If they are sown in April, May or June they will be ready for harvest in June, July or August, while the quicker non-auto-flowering plants will only be mature in mid-September at the earliest.

In indoor crops, auto-flowering strains at day eighty or ninety are not that attractive, as they take as long as a cutting that normally flowers after one or two weeks of growth, completes the vegetative and blooming stages in three months and achieves more potency and a higher yield. In my opinion the most useful function of autos grown indoors is the opportunity to fill free spaces in the mothers’ grow room or in the vegetative grow room in order to produce a few extra buds, despite the photoperiod required for growth.

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