Czech law allows you to legally grow up to three plants at home and to possess no more than 100 grams of dried cannabis in the household at any one time. It is understandable that many beginner growers ask how much cannabis they can harvest from one plant. The truth is that the answer is nowhere near as simple as legislators might imagine. Cannabis is an incredibly versatile species, and the differences in harvest between individual plants can be enormous. It depends on the strain, the growing style, the conditions and many other factors.
It stands to reason that plant size will be one of the main factors affecting yield. The maximum growth of a plant is genetically determined, but generally speaking, the more space the roots have, the larger the plant will grow. That is why cannabis grown outdoors in open ground can reach truly majestic proportions, and it is easy for one plant to produce many times more dried flowers than the permitted amount. Indoor-grown cannabis usually does not reach such dimensions, and the harvest from one plant typically ranges from tens to hundreds of grams of dried flowers.
The appearance and structure of cannabis plants are influenced by genes inherited from the parents. Sativa strains are tall and slender, with nodes far apart, and tend to have rather sparse flowers. On the other hand, pure indicas are shorter, with more compact buds and shorter internodal distances. The density and compactness of the flowers affect yield. It is clear that from a bushy plant with plenty of side branches it is possible to harvest more, and sparse buds weigh less than those that are rock hard. Most modern strains are hybrids between indicas and sativas, however many of them retain some characteristic morphological traits.
Kush-type strains: Kush is renowned for its distinctive terpene profile; however, this exclusive aroma comes at the expense of flower structure, which has an elongated triangular shape and can be rather sparse in some cultivars. That does not mean, however, that we cannot find kush with a nice bud structure. Definitely worth trying is Strawberry Lemonade (Barney’s Farm) with its breathtaking citrus aroma, the tough-guy delicacy in a modern guise Zombie Kush (Ripper Seeds), or the sweet Bubba Kush (HiSeeds).
Cookies (Girl Scout Cookies, GMO, Thin Mint GSC): The origin of the strain that conquered America years ago remains a mystery to this day. Nevertheless, in recent years it has become one of the most extensively bred strains, giving rise to many a competition-winning classic. In addition to its characteristic terpene profile, it also passes on the structure of flowers, which are exceptionally compact. It is difficult to choose the best among all the “cookie” strains, but among our favourite variations are Gelato, Wedding Cake or the original Cookies.
Critical: The legendary strain originally from Mr. Nice Seeds (Critical Mass) is among the Dutch classics. The original cross between Skunk #1 and landrace Afghani was characterised by huge yields and a short flowering time. In the following years, Critical became a tool for breeders to add yield to their cultivars. Worth mentioning, for example, are the robust Criminal+ (Ripper Seeds) or the autoflowering Critical+ Auto (Silent Seeds).
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Factors affecting plant yield
Genetics and the growing site are by no means the only things that affect whether cultivated plants fulfil their genetic potential. It is also important whether, during their life cycle, they receive everything they need for vigorous growth. The main environmental factors affecting yield are:
Light: Cannabis thrives in direct sunlight, and the more light energy it receives, the more it will grow. Of course, this is only the case if it has enough nutrients and water. When growing outdoors, it is best for the plants to be placed in a location where the sun shines all day. Indoor growers can choose from dozens of types of grow lighting, from a few-watt panels for seedlings to powerful LED panels whose output corresponds to midday sun. With these, it is possible to harvest even hundreds of grams per square metre of growing space.
Water: Without enough water, the plant will not grow, but overwatering can be just as dangerous as drought. When growing in pots, it is necessary to ensure good drainage so that water does not stand around the roots and the plant can breathe. Outdoor plants usually manage with natural rainfall, but during dry periods it is necessary to water regularly, ideally in the morning or evening. In indoor growing, it is also important to monitor humidity — too low stresses the plant and slows growth, while too high can encourage mould.
Temperature: The optimal temperature range for cannabis growth is between 22–28 °C during the day and 18–22 °C at night. At higher temperatures, there is a risk of overheating and slowed growth, while temperatures that are too low can stop the plant’s metabolism. Outdoor growers can do little about this, but indoors the environment can be well regulated using ventilation, fresh air intake and air conditioning. A stable temperature without fluctuations will directly translate into vitality and yield.
Nutrition: Like any other plant, cannabis needs enough nutrients for growth. The basis is three main elements — nitrogen (N), phosphorus (P) and potassium (K) — which are used in different ratios during growth and flowering. In the growth phase, the plant needs more nitrogen, while in the flowering phase it needs more phosphorus and potassium. In addition to these macronutrients, a sufficient supply of micronutrients such as calcium, magnesium or iron is also important. Overfeeding can, however, do more harm than good, so it is worth using high-quality fertilisers designed specifically for cannabis and following the manufacturer’s recommended dosage.
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Techniques and procedures affecting plant yield
Cannabis growers use countless techniques to influence plant yield. Most often these are various ways of shaping the plant, such as trimming, tying down or breaking. The length of the individual phases of the growing cycle also affects the amount of cannabis harvested.
Top trimming – topping: Most growers trim the tops of their plants at least once, or more often, during the growing cycle. This is because, if left alone, cannabis plants grow in the shape of a Christmas tree with one main top. If the main top is cut during the vegetative phase, four new ones will form in its place, and the same applies to each additional top that is cut.
LST (Low Stress Training): Various tying, bending and breaking techniques are usually used to maximise growing space in indoor cultivation. Popular methods include SCRoG (Screen of Green), where plants are woven into nets in order to create an even canopy.
Length of vegetative growth: The length of the vegetative (growth) phase has a fundamental effect on the final size and yield of the plant. The longer a plant remains in the vegetative stage, the more it will grow and the more substantial its root system and canopy will become. Indoor growers can influence the length of growth by setting the light cycle (usually 18 hours of light per day), while outdoor plants follow the natural length of the day.
Autoflowering strains: Autoflowering strains are usually smaller in stature than their photoperiod sisters. This can be an advantage if the aim is to keep yields under control, for example when growing outdoors. On the other hand, autoflowering plants do not allow much room for error, and if they do not grow well in the first few weeks, they will not provide a very large harvest.
As you can see, the yield from one cannabis plant depends on a whole range of factors — from the genetic basis, through the environment, to the grower’s experience. Every plant is different, and with a little care, patience and the right technique, it can surprise even a beginner. If you want to know more about individual strains, growing methods or interesting facts from the world of cannabis, have a look at the HiSeeds blog.