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Cannabis seed life line

From Seed to Harvest: The Life Cycle of Cannabis

Knowing how to care for your cannabis plants at each of the four distinctive stages of their life cycle will provide a solid baseline of knowledge and healthy, productive gardens.

It can take four to eight months to grow a cannabis plant. During this time, it goes through four distinct stages: germination, seedling, vegetative, and flowering. It is essential for cannabis growers to understand each stage in the life cycle so they can properly care for their plants. Each phase requires different nutrients, hours of light, and type of light. There are also different tasks that can help make each stage more successful.

Germinating cannabis seeds.

Germination Stage

It all begins with a seed. If stored in cool, dark conditions, a cannabis seed can remain viable for years. The best seeds are hard and dry and will be light to dark brown in color. Underdeveloped seeds tend to be soft and either white or green. It’s very unlikely these seeds will germinate.

The seed lies dormant until it is exposed to warmth and moisture. You can germinate your seeds by planting them in a moistened seedling starter mix, covered with plastic and placed on a heat mat. It is important to use a seed-starting mix instead of potting soil.

There is enough nutrition in a seed to feed a sprout for about two to three weeks. Any additional fertilizer can burn your plants at this tender age. Once planted, a seed can take five to 10 days to sprout.

Once your seeds have sprouted, the two seedling leaves will be the first to appear. Place a fluorescent grow light about two inches from the top of your plants for 18 hours per day. You don’t need a powerful light for them in the beginning. When the true leaves appear, your little plants can officially be considered a seedling.

Cannabis plant in its seedling stage.

Seedling Stage

The seedling stage of cannabis plant lasts three to six weeks, depending on environmental factors and the strain you’re growing.

During this time, your seedlings are focusing their energy on growing roots and foliage. Because the roots are so small, be careful not to overfeed or overwater. Use a fertilizer high in nitrogen and be sure to dilute it so you don’t harm your plants.

Fluorescent lights still work well at this point. Set your timer so the lights are on for 18 hours and off for six.

Seedlings are susceptible to pests and disease at this age, so this is a good time to apply a preventative neem oil treatment. It’s much easier to prevent spider mites and powdery mildew than to treat them while your plants are so young. If they do get infested or infected at this age, the stress on your plants will likely produce a smaller harvest down the line.

Cannabis in the vegetative stage.

Vegetative Stage

After a few weeks as seedlings, your cannabis plants will outgrow their starter pots and start demanding more food and light. The roots and foliage grow rapidly during this stage, which allows the plant to take in more nutrients and carbon dioxide. Don’t be surprised if your plant shoots up two inches in one day!

If you don’t already know, this is when you’ll be able to identify whether you are growing an indica or sativa. Indicas tend to be short and bushy, while sativas are lanky with less foliage.

You will also be able to identify the sex of your plants. About four weeks into the veg cycle, pre-flowers start to appear. By six weeks in, you should be able to determine whether those new buds are male or female. Most growers remove the males from their garden, so they don’t pollinate the females and cause seeds to form.

When growing indoors, the vegetative stage can last one to four months, or even indefinitely in the case of mother plants. You control the length of this phase by the number of hours of light you give your plants. As long as they receive 18 hours, they will remain in this stage.

During the vegetative stage, you’ll need to trade in your fluorescent lights for a metal halide or powerful LED. This blue light mimics the light in spring and sends the message to grow roots and foliage to prepare for the flowers.

If you haven’t already, transplant your cannabis into larger pots and start feeding them more. As they grow, be mindful you will need to increase the PPM of your nutrient solution and transplant them into larger pots as needed.

At this age, your plants need high levels of nitrogen and modest amounts of phosphorus and potassium. Silicon is also beneficial at this stage because it helps to build strength in the stalk and stems, which you’ll need to support those big buds that will soon grow.

As your plants grow taller and fill out, you’ll need to start pruning and training them. This focuses their energy on growing large colas, opens up the plant so light can reach all the leaves, and prevents fungal diseases by increasing air flow.

The general rule of thumb is to flip the lights to 12/12 and trigger the bloom cycle when your plants are about one third of the size you want them to be at harvest.

Flowering Stage

You imitate autumn in your garden when you reduce the light to 12 hours on and 12 hours off, and switch to a red high-pressure sodium bulb. This triggers your cannabis plants to start blooming so they can procreate before they die at the end of the season.

The flowering stage lasts six to 10 weeks, depending on the strain you’re growing. During this time, dense buds covered in a sweet-smelling, sticky resin will form on your plants. This resin is where the THC and terpenes are, and so growers do whatever they can to grow the stickiest colas possible.

Your fertilizing schedule will change during this stage. Start feeding your plants minimal amounts of nitrogen, moderate amounts of potassium, and high amounts of phosphorus. This is the time to add bloom boosters and sugars to your regimen.

Be on the lookout for nutrient deficiencies or toxicities during this phase. Brown leaf tips can signal nutrient burn, while yellowing leaves may indicate a nutrient deficiency. It is normal, however, for the lower leaves to turn yellow towards the end of the flowering cycle, when your plants feed on themselves for more efficient nutrition.

Keep feeding your plants until about 10 days before harvest, and then stop fertilizing and flush your crop. This clears your plants of excess nutrients and is crucial to making sure your end product is smooth instead of harsh.

As your buds grow large and dense, environmental conditions and poor air flow can cause bud rot. If you don’t catch it in time, you can lose all of your plants. Keep a close eye on your buds as harvest time approaches. Inspect your buds often and harvest immediately if you see signs of rot. If you catch it early, you can cut the rot out of your buds and salvage most of your crop. You’ll know your cannabis is ready to harvest when the pistils, or the hairs, turn the color of rust and the resin changes from clear to a milky white.

If you understand the life cycle of cannabis, you’ll be able to care for your plants the right way in each stage of their life and anticipate problems before they occur. You’ll be a better grower and have top shelf smoke to prove it.

Anatomy of the Cannabis plant

When it comes to cannabis, the part of the plant that gets all the attention is naturally the bit we’re all growing for: the flowers. But while it’s easy to be enamoured with the beautiful frosty flowers we shouldn’t overlook the rest, because behind the bud there’s a whole plant, with all its component parts, each playing an essential role in bringing us our precious harvest.

Here at Alchimiaweb we strongly believe that the more we know about our favourite plants, the more success we’ll have cultivating them, and the happier we’ll be with the results! For these reasons here we’re going to take a closer look at the cannabis plant and identify all the different elements of its anatomy to help you get to know this wonderful plant a little bit better.

1, male flower, enlarged detail; 2, pollen sac; 3, pollen sac; 4, pollen grain; 5, female flower with bract; 5, female flower, bract removed; 6, female seed cluster, longitudinal section; 7, seed with bract; 8, seed without bract; 9, seed without bract; 10, seed cross section; 11, seed longitudinal section; 12, seed without hull (Franz Eugen Köhler 1887)

The Cannabis seed

For most of us, our introduction to cultivation comes when we buy or are gifted some cannabis seeds for the first time, so let’s set out on our examination of cannabis anatomy starting with the seed.

A healthy, mature cannabis seed will be well-rounded in shape with one pointed end and one flat end. They have a tough outer casing that is rigid to the touch, preventing the seed from being easily crushed. A seam separates the two halves of the shell (also known as the hull or pericarp) and is where the seed opens during germination.

Depending on their genetics, seeds can vary greatly in size, from really tiny (800 seeds per gram) to absolutely massive (15 seeds per gram). In mature seeds the outer shell should be covered with attractive dark markings known as “tiger stripes” which, like snowflakes, are unique to each seed and are in reality a thin layer of cells coating the seed and can be rubbed off easily, revealing the true tan/beige colour of the seed beneath.

Detailed view of a cannabis seed

Inside the seed we will find the embryo of the plant, everything needed to start a new life, dormant until the right conditions of moisture and warmth are met. We have the root, or radicle as it’s known while still in the seed, the cotyledons, those first, fat, rounded embryonic leaves containing the seed’s food reserves for early development. Cannabis is a “dicot” plant, meaning it has two cotyledons. Situated in between the cotyledons, surrounded by the first two true leaves is the apical tip, the point from which the plant will continue growing once germinated.

Roots

When we germinate a cannabis seed, the first thing that emerges from the opened seed will be the tap root which will begin to grow downwards, seeking out moisture and nutrition and colonising the substrate. The root system has three main purposes, not only does it anchor the plant in the substrate, it provides it with water and the nutrients, and it also acts as storage for sugars and starches produced by photosynthesis. It’s hard to overstate the importance of the roots in cannabis cultivation, they really are the foundation upon which everything else is built, without healthy roots we won’t harvest beautiful flowers!

Roots themselves can be classified into three types. Firstly the tap root, which is the principal component of the root system, the subterranean counterpart to the plant’s main stem, pushing vertically downwards and shooting off branches as it grows. These branches are the second type, the fibrous roots, which branch off from the tap root, extending outwards to form an underground network approximately the same size as the aerial part of the plant. A third type of roots are known as adventitious roots, these are the thick roots that sometimes sprout from the stem just above ground. These are the roots that make it possible to reproduce plants by taking cuttings and cloning them.

Adventitious root growing from the stem of a clone

Cannabis plants grown from seed will start life with a tap root system that develops into a fibrous root system, while clones don’t have a tap root, starting instead with adventitious roots before developing a fibrous root system. In all cases, a root system needs an adequate balance of moisture and air to be healthy and if care and conditions are right we will be able to see thick, bright white roots with plenty of fine hairs when we transplant.

The root crown

The part of the plant where the roots and stem join is called the root crown, or sometimes collar, or neck. This is a vital part of the plant, the dividing line between upward and downward growth, where the vascular system switches from roots to stem, and one of the places in the plant where most cell division takes place.

The root crown is naturally situated very close to the surface, where aeration is at its most, however some growers will transplant with the crown buried well below the surface, which encourages adventitious roots to sprout from the buried section of stem. It’s good way to deal with those leggy seedlings that stretched to get to the light and ended up too tall.

Stem and nodes

The stem of the cannabis plant is the part responsible for keeping the plant upright and for supporting the weight of the plant. It contains the vascular system which works to carry moisture and nutrients from the roots to the leaves via xylem cells, and to transport the sugars and starches produced via photosynthesis around the plant for use or storage via the phloem cells. Phloem is otherwise known as bast, the part of the cannabis or hemp plant that is traditionally harvested for fibre to make rope, canvas etc.

Cross section of stem showing a node

The stem, which can sometimes be hollow, is divided by nodes where the lateral branches begin, with the space between them being known as the internode. Seedlings will begin by growing opposite pairs of nodes and leaves but as time passes the nodes will start to grow alternately, sign the plant is mature and ready to flower.

Taller, stretchier Sativa plants will have a larger internode spacing than squat, compact Indica varieties, although environmental factors can also influence internode space. The nodes are where the first flowers appear (pre-flowers), so it’s the first place growers look when trying to determine the sex of plants grown from regular seeds. The small, narrow spear-like leaf growing at each node is called the stipule, and shouldn’t be confused with pre-flowers.

Nodes are one of the parts of the cannabis plant where most growth happens and most hormones are produced, for this reason we always cut clones with at least one node to be planted below ground in the substrate, so it can produce auxins (rooting hormones) to begin root development in the undifferentiated meristem cells of the node.

Leaves and petioles

Cannabis leaves are palmately compound (shaped like the open hand, with multiple parts), with anything from 3 to 13 veined, serrated leaflets or fingers. Indica varieties will generally have wider and shorter leaflets of a lush dark green colour, but fewer in number, while Sativas will have longer, narrower leaflets and can be of a lighter green shade. Of course, cannabis is a hugely diverse genus and there are exceptions to this rule, most notably the Ducksfoot variety, with its webbed leaves. Autoflowering varieties will tend to have smaller leaves, with the shape depending on the individual genetics, but as a general rule leaning more to the Indica side.

Leaf and structure comparison of the different cannabis species

A cannabis plant will have large and small fan-type leaves, which we remove and dispose of at harvest time, and also sugar leaves, which are the small, resin-covered leaves that protrude from the bud. These will either be trimmed away and kept aside for resin extraction, or simply left on the bud and smoked with the flowers.

Leaves from two different hybrids

As a seedling grows, each set of leaves has an increasing, odd number of leaflets, so the first set of leaves above the cotyledons will almost always have a single leaflet, the second pair will have three, the third will have five and the fourth will have seven leaflets, and so on until the plant reaches the usual number as dictated by its genetics.

The leaflets join at the point known as the rachis, from where they attach to the stem or branch by a leaf-stem known as the petiole. Petioles can be of varying length depending on the variety and can naturally vary in colour from green to dark purple, although in normally green plants a purple petiole can often be a sign of a phosphorous deficiency.

The fan leaves function both as solar panels and air conditioning for the plants, with the darker green upper side of the leaf producing energy via photosynthesis and the underside regulating internal processes via stomata, tiny pores that absorb the CO2 needed for photosynthesis and at the same time release water and oxygen. The stomata will close at night to conserve moisture and during the day will respond to heat and humidity levels, opening and closing to constantly balance internal moisture levels with external environmental conditions and keep metabolic functions working.

Flowers

Cannabis is dioecious, meaning the male and female reproductive organs are on different plants. Unless we’re planning on doing some home breeding and making seeds, we won’t be growing any male plants to full maturity, but it’s important to be able to identify them, even if we’re growing exclusively from feminised seeds, just in case.

Female pre-flowers on the left, male flower cluster on the right

The male, staminate flowers effectively resemble green balls on sticks, composed of five petals which open to reveal five pollen-producing stamens. They grow in long, loose bud clusters from internodes on the branch and once pollen is released the male plants will soon die off. Male flowers contain low levels of cannabinoids and terpenes.

Female pistillate flowers are formed of tight clusters of bracts, the small, teardrop-shaped green petals that we growers refer to as calyxes. Each bract or calyx contains the ovary and the pistillate hair or stigma, which is what growers call the pistil and is the part of the flower that catches airborne pollen. Once pollen lands on the stigma, it is transported down the pollen tube to the ovary where fecundation takes place and the seed is formed, filling and swelling the bract as it grows. The thick, white pistil or hair will shrivel and turn a brown or red colour one it has served its purpose. The seeds are usually mature after a further 4-6 weeks time.

Both cannabis flowers and leaves develop beautiful colours

After pollination, female plants will devote their energies towards seed production, at the expense of resin. This means that seeded buds will have lower levels of cannabinoids and terpenes, and is one of the main reasons we strive so hard to grow sinsemilla (seedless) flowers, quite apart from the awful taste of smoking a seed in a joint!

Trichomes

Trichomes clustered on a bud

Botanists are still unsure as to exactly why cannabis plants produce such a large quantity of trichomes, but most agree that they most likely have the function of protecting the flowers and developing seeds, whether from harsh UV light, insects, grazing animals or extremes of temperature.

Trichomes have two different basic types: Glandular and non-glandular, with the principal difference being that non-glandular trichomes grow without a trichome head or gland, having the appearance of small hairs and mainly developing on stems, leaves, petioles and to a lesser extent on the flowers themselves, while glandular trichomes are found mainly on the flowers and sugar leaves, and possess the resinous gland where the cannabinoids and terpenes are secreted.

Glandular trichomes under the microscope

Glandular trichomes are themselves divided into three main kinds, which are: bulbous, the smallest and least numerous; capitate-sessile, which are larger and grow low, close to the leaf surface; and finally capitate-stalked, which are the largest, most numerous trichomes, found in highest concentration on the flowers and those with the greatest cannabinoid content, appearing somewhat like a tall mushroom, with a long stem and a large, rounded head – the iconic image of a trichome.

As the flowers mature, the trichomes will change colour, starting out transparent, passing through a milky-white stage nearing maturity and going on to become amber coloured when fully mature. Different growers will harvest their flowers depending on personal taste and the effect they’re looking for, but on our blog you can read a useful guide to harvesting according to trichome ripeness, which will help you to bring your crop down at the optimum moment.

Hopefully after reading this you’re now a bit more familiar with the anatomy of the cannabis plant and will become a better grower as a result. Knowledge is power!

The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.

The Life cycle of Cannabis: From seed to harvest

Cannabis passes through a series of stages in its life. The most important of these are the germination, seedling, growth and flowering stages. Each stage brings its own challenges. Novice growers need to be aware of these, to be sure of giving their plants the attention and care that they deserve.

Plants are living beings. They are at the base of the evolutionary tree, they heal our bodies and souls, they delight our senses. I think all our readers know by now which is our favourite plant: Cannabis sativa L. – a fantastic crop and medicinal plant, and one of the oldest plant genera in the world.

No matter why cannabis is being cultivated, to see with your own eyes how a small seed grows into a bulky plant, which then starts flowering, is a moving experience every time.

Cannabis is an annual plant, so its entire lifecycle takes place within a single year, with most varieties reaching the end of their life after between four and ten months. In general terms, the following four stages of life can be distinguished:

  • Germination stage
  • Seedling stage
  • Growth or vegetation stage
  • Flowering stage

A quick glance is usually enough to determine the current stage. Over time, it is not just the appearance of the plant that changes, its needs also change. Different stages require different quantities of light, water and nutrients. Furthermore, if you want to determine the sex of the plant or prune it, it is useful to know which stage the plant has currently reached.

1 – Germination stage (1 to 2 weeks)

All forms of life start from a seed of some kind. High-quality seed is the single most important factor for successful cultivation. Cannabis seeds should be hard, dry and brownish in colour. There are a number of different ways of getting the seeds to germinate. The easiest is the paper towel method.

In the germination process, the germ in the seed breaks through its shell and forms a root, which is known as the taproot. Germination takes anything from 24 hours to 7 days. Generally cannabis varieties with a high proportion of Indica germinate faster than pure Sativas.

The germinated seed can now be placed carefully into the growing medium. The plant will start to grow and force its way upwards.

While the first two cotyledons (seed leaves) are being formed, the plant shrugs off the protective seed husk. That signifies the end of the germination stage.

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2 – Seedling stage (2 to 4 weeks)

Particular care is necessary at this stage in the lifecycle. Seedlings are susceptible to illnesses and mould. Many novices get carried away with watering and give the seedlings too much fertiliser. Even if you plan to grow outdoors, it may be useful to give the plants a healthy start indoors, assuming that a location is available with adequate light (e.g. a windowsill). The plants need as much light as possible at this stage.

How long the seedling stage lasts depends on the variety and on the environmental conditions. The main focus of the plant is on developing a root system. This forms the foundation for its later growth.

Meanwhile the plant will grow its first “real” leaves with the characteristic marijuana shape.

The leaflets are long and jagged. Initially a leaf has just one leaflet, although a mature cannabis plant will have five to seven leaflets per leaf.

Once the plant produces the full count of leaflets for each new leaf, the seedling stage is over.

3 – Growth stage or vegetation stage (2 to 8 weeks)

Now the plant starts its main growing phase. Provided it receives enough light, it can grow up to two inches (5 cm) in a single day. It is obvious that the plant needs to be repotted if it is still growing in a small pot.

Leafy plants like a healthy soil that is rich in nutrients. The production of chlorophyll and proteins depends on a supply of nitrogen. It is worth investing in the right kinds of fertiliser or even producing them yourself.

As it grows, the plant also needs more water. Young plants are best watered close to their stem, but later on water should be distributed more widely so that the tips of the roots can absorb water more efficiently.

Have you ever heard of topping, super-cropping or lollipopping? Using these techniques you can train cannabis or manipulate the shape of the plant. Growers use them to develop stronger plants with more buds. Opinions vary, however, on whether these techniques actually deliver results. They are only necessary for special cultivation methods such as the Screen of Green (SCROG).

How long the growth phase lasts is not a simple question to answer. Autoflowering cannabis varieties move automatically on to the flowering stage within 2 or 3 weeks. Regular or feminised varieties only start flowering once the days become shorter (outdoor cultivation) or the grower reduces the lighting period to 12 hours (indoor cultivation).