The cannabis flowering stage, or ‘bloom’, is where your cannabis plant produces the resin soaked buds. When growing photoperiod feminised cannabis seeds indoors, the flowering stage begins once there are around 12 hours of daily light. When growing autoflowering cannabis seeds, bloom begins automatically at a point pre-determined by the auto genetics. This usually happens around 4-6 weeks after seed germination. If you want a handy re-cap of the basics in the cannabis seedling, veg and flowering stages, the following guides may be useful background reading.
It’s critical to care for your cannabis plant well during the flowering stage in order to maximise the quality and quantity of the harvest. After all, there is little point optimising your grow room and investing in the best lights, seeds & nutrients only to deliver substandard bloom conditions.
If you can optimise flowering conditions and avoid the most common mistakes you will be able to enjoy growing some premium quality buds. Here is the Dutch Passion top-5 list of cannabis flowering stage mistakes to avoid.
1. Overdoing cannabis nutrients and pH levels
Over-feeding your cannabis plants in bloom is one of the most frequently seen mistakes by cannabis cultivators, especially the less experienced. The logic is perhaps easy enough to understand:
More nutrients should mean bigger crops. But the reality is that over-feeding your cannabis plant burns the root system and damages overall plant health. In the worst cases a severely over-fed plant will suffer from extreme nutrient burn and will be permanently stunted or may even die.
Cannabis nutrients tend to be gradually and slowly increased in strength as the plant matures. The first sign of over-feeding should be a clear warning to the grower to reduce nutrient concentrations. Knowing when (and how quickly) to increase nutrient concentrations is a skill which comes with experience. Those afraid of over-feeding their cannabis plants may wish to consider the use of slow-release organic nutrients such as those from BioTabs.
Using slow-release nutrients can mean that the grower only has to ‘feed’ the plants with plain water for much of the grow. This greatly simplifies cultivation, removing the risk of over/under feeding and is highly recommended.
Since you are only feeding with water much of the time this approach also removes some of the dangers of incorrect pH issues. Less experienced growers in particular may get the most benefit from slow-release organic nutrients since there is less to go wrong.
Maintaining correct pH is important during bloom. For those using hydroponic grow systems a pH of around 5.6 – 5.8 is often used. Soil growers often find that soil acts as a natural buffer, meaning that few soil growers worry too much about pH. One useful tip to any grower that routinely monitors nutrient pH is to regularly check and calibrate your pH meter to ensure accurate readings. Many top growers keep a spare pH/EC meter just in case their main meter starts to give erroneous readings.
2. Incorrect lighting setup for indoor growers
An optimised cannabis flowering stage requires light intensities and wavelengths to be correctly tuned to the bloom requirements. If you use the wrong type of lights or the wrong intensities, you will compromise both the quality and quantity of your harvest. During bloom you will need a red-dominant light spectrum which allows heavy production of buds and resin. You will also need to aim for intense light levels.
Serious growers use PPFD light levels of 800-1000 to maximise harvest quantities. You can bloom with less intense light but this will reduce harvest quantities. Many professional growers, as well as the most serious home growers, will use LED grow lights. These have an optimised spectrum and inherently lower heat than HPS, but they are more expensive to buy. However, they are cheaper to run and should last longer.
Often, the highest cannabinoid levels and terpene levels come from grow rooms that use quality LED light fixtures. Although a good quality LED light is one of the most expensive grow room upgrades that you will ever make, it is also one of the most effective. For the average grower, upgrading from HPS to LED allows new quality levels to be achieved. One tip for indoor lighting is to supplement your LED light with a UVA/UVB light, this can improve terpene and cannabinoid levels.
3. Male cannabis plants pollinating female plants
If you have carefully selected and grown your cannabis seeds the last thing you want to do is mess up the grow by allowing the crop to be seeded by a rogue male or hermie plant.
Few modern growers outside of the breeding community want to grow male cannabis plants. That’s the main reason that most people grow feminised cannabis seeds or autoflower seeds. For most growers, the biggest risk of accidental pollination of their crops is from a hermaphrodite or ‘hermie’ plant.
Hermies are typically female plants that produce a small number of male flowers. The male flowers release pollen that can cause cannabis seeds to form in the buds. If hermie plants are seen the male flowers are usually removed quickly with some wet tissue paper. In severe cases, it’s safer to completely remove the hermie plant.
Keep in mind that just about any cannabis strain can show hermie tendencies if stressed enough. But if you choose good quality cannabis seeds from a reliable seedbank, and if your grow room conditions are reasonably good them you shouldn’t see many hermies.
4. Underestimating the risks of humidity and mold
High levels of grow room humidity during bloom can increase the risk of mold and bud rot. Heavy yielding cannabis strains can produce long, thick blooms full of dense cannabis buds. Many experienced growers deliberately keep Relative Humidity (‘%RH’) below 45-50% during the flowering stage in order to minimise the risk of mold and bud rot.
Indoor growers can use extraction fans to ensure their grow rooms have a constant supply of fresh air to keep their %RH levels in check. Outdoor growers have to rely on correct choice of outdoor cannabis seeds which are naturally resistant to rot/mold, powedery mildew, and other related diseases.
Losing an indoor cannabis crop to mold or bud rot is particularly depressing for any grower. The frustration is maximised by the fact that harvest was within reach. So keeping a particularly close eye on your plants and monitoring them for humidity and mold during bloom is always good advice. If necessary, a de-humidifier can be used to reduce RH levels inside your grow area.
5. Harvesting too early or too late
If you have paid premium price for the finest cannabis seeds and grown them to the best of your ability you need to make sure that you harvest them at the right moment! Some growers like the energetic vibe that comes from early-harvested buds. Perhaps more growers prefer the heavier effects that can come from late-harvested buds. It’s a great idea to know your own preferences.
It can be worth picking some early and late buds from your next harvest and comparing them to your normal harvest point. Some growers discover that they e.g. prefer to leave their buds for an extra week or two to get a few more amber trichomes and a heavy hitting harvest. But knowing how YOU prefer your buds harvesting and picking the buds at the optimum moment for your personal preferences is part of the joy of home growing.
Some growers love the heavier, stony feelings that come from buds that have been allowed extra bloom time. If that sounds like you then there is no point rushing your harvest by a week or two and compromising the effects.
Conversely, those that like early harvested buds with clear trichomes needn’t waste valuable time at the end waiting for buds to ripen further than necessary. Remember the great benefits of growing your own cannabis seeds include selecting which genetics to grow as well as deciding the harvest point which suits your personal preferences. On top of that growing your own cannabis is the most cost-effective way to guarantee a supply of top-quality buds.
Other useful tips for cannabis bloom
For many growers, bloom is the most exciting and rewarding part of cultivation. You can see the buds form and swell. You can enjoy the scents as the terpene profile builds and watch the trichome resin glands start to coat your buds. There is a lot going on, a great deal to enjoy and one or two things to keep an eye on:
Indoor growers can get caught out if they don’t deal with the strong odour from cannabis in bloom or drying. Always use a carbon filter and check for leaks in pipework or leaks in the joints between pipes and filters/fans. Pro-growers keep a spare carbon filter ready for that inevitable day when the old one starts to fail.
Keep spare nutrients
The competent grower is well prepared and unlikely to be caught out by bad planning. Make sure you don’t need to panic because you run out of key materials, nutrients (or equipment) during bloom. You may also want to keep spare calibration solutions for your pH meters and EC meters too. Those growing with HPS lights often keep a spare bulb just in case of a failure.
Outdoor grow security
As bloom approaches some outdoor growers use a trail-camera to take pictures of any intruders near their plants. Getting your outdoor plants stolen (or ‘ripped’) just before harvest is one of the most painful experiences for any grower. But careful selection of your outdoor grow site can be the best way to keep it private for many years of successful growing. Avoid leaving obvious tracks and pathways through the fields/countryside to your grows.
Choose the right cannabis seeds!
Even the world’s best grower won’t produce a high-THC crop from low THC cannabis seeds. Nor could they produce XL harvests from poor yielding cannabis genetics. The price difference between the best cannabis seeds and mid-range seeds is often just a couple of Euros/Dollars/Pounds per seed. Research your seeds carefully and buy the best cannabis seeds from a supplier with a long track record for excellence. A history of cannabis cup wins is always a sign that your cannabis seed supplier takes their job seriously!
Enjoy the cannabis flowering stage
Most of the time you will find that flowering goes smoothly and without incident. If you have chosen your cannabis seeds wisely and used a well-designed grow room there really isn’t that much to be concerned about. Indeed, many growers describe the flowering stage as the most exciting and satisfying part of the entire grow. Your hard work and patience are rewarded with great views and aromas, anticipation builds as the blooms swell! You have worked hard to get your plants to the bloom stage, enjoy this final part of the cultivation process!