Ask the expert: optimal flowering, germination problems, and efficient cultivation

In this article, we address the most common questions that cannabis growers ask us through our ’Ask the expert’ section. From germination techniques and specific care for different stages of growth, to solving common issues and optimising the growing environment, our experts offer detailed answers and practical tips to ensure a successful harvest.

On this occasion, we address several questions, such as the length of the flowering phase of our Kannabia strains; and we clarify if the pre-flowering is included in this period. In addition, we explore alternative germination techniques for seeds that haven’t thrived with the traditional wet paper towel method. We also discuss the causes and solutions for pale and dry leaves, including irrigation and fertilisation adjustments. Finally, we offer some top tips on the optimal planting distance between autoflowering strains in a greenhouse. So let’s begin!

Hi, I’m at day 38 of flowering. What’s the maximum humidity level that I can have in my grow tent right now? It is currently between 45 and 55%. Is this optimal for this stage of ripening or is it too high? (Tomás)

Optimal humidity during the flowering phase is crucial to prevent issues like mould. On day 38 of flowering, your plants are at an advanced stage of development, so relative humidity should be kept between 40 and 50%. If humidity levels in your grow tent are currently between 45 and 55%, that’s slightly above the upper optimal range for the final stages of flowering. While 50% is alright, 55% may be a bit too high, especially when the plants are approaching maturity. Ideally, you want to reduce it a little to ensure that it remains within the 40-50% range.

Hi, I have 2 plants: one Gelato-K and a Baby Boom Auto. How long does their flowering last? Is the pre-flowering included in the flowering phase? So, is it 2-3 weeks of pre-flowering + the flowering phase, or does it refer to both when you say 8-9 weeks? (Jan)

The pre-flowering is a transitional stage that occurs when the plants begin to show the first signs of flowering, but aren’t yet in full bloom. For most photo-dependent strains, this phase lasts approximately 1-2 weeks. Generally, when a plant is said to have a flowering phase of 8-9 weeks, this refers to the main flowering phase and does not include the pre-flowering. Therefore, for a plant like Gelato-K, you would have about 2 weeks of pre-flowering followed by 8–9 weeks of flowering, totalling about 10-11 weeks from the beginning of the pre-flowering to harvest. Baby Boom Auto is an autoflowering strain that starts flowering automatically. It has a full life cycle of approximately 60–65 days from germination, including both the growth and flowering phases. To sum up:

• Gelato-K: 8–9 weeks of flowering (not including the pre-flowering).
• Baby Boom auto: 60–65 days from germination to harvest (including all phases).

I have a Dosidos Auto mutant plant. Can it come from a special edition because there is no evidence, like most ‘limited/special’ collections, which are due to small reproduction batches? It’s the first time I have a mutant plant, so I’m just growing it to see what it does. (Grass Leaf Original Ltd).

Our Dosidos Auto does not come from a “special edition. Seed editions are often considered ‘special’ or ‘limited’ for several reasons. This is often because they are produced in small batches, when breeders are experimenting with new genetic combinations and don’t have a great number of seeds available. These special editions can also be at an experimental phase, when breeders and growers are still watching how these plants behave in different growing conditions. They can exhibit distinctive characteristics that make them special (such as unique terpene profiles, high potency levels, or high resistance to pests) but still be in the verification and stabilisation phase. Although you may not have as much information about them as with more common strains, growing these plants can be a truly enriching experience. Therefore, as yours is a mutant plant, make sure you keep a close eye on it and enjoy the process of discovering its peculiarities.

I have two 5+2 packs, one of Kiss and the other of Afrodite. I’ve been trying to germinate in a container with wet napkins, but I’m having difficulties. Is there any other method that’s more effective? (Héctor)

Germinating cannabis seeds can be a delicate process; and, although the wet napkin method is quite popular, this doesn’t mean it works every time. If it hasn’t worked for you, you can try direct germination in substrate, rockwool cubes, or Jiffy pellets. Having said that, it’s always best to place the seeds in a glass of water at room temperature for 1-2 hours so they hydrate more quickly. After that, it’s time to transfer them to a germination medium such as a wet paper towel or directly to the substrate, and always maintain a constant temperature or around 20-25°C. If possible, use distilled water or rainwater since tap water may contain chlorine and other contaminants that could affect germination. And remember: some seeds may take longer than others to germinate, so give them enough time before getting rid of them.

The leaves on my plants are very pale and feel dry to the touch. I’m watering with dispenser water and I’ve lowered the pH to 6.5, or sometimes to 6.0. I’m fertilising with Topcrow Auto and Candy in 10 litre pots, with a ratio of 1 litre per pot. What am I doing wrong? (Franco S.)

Pale, dry leaves may be caused by several factors. It could be due to a nutrient deficiency that indicates a lack of nitrogen, iron, or other essential compounds, so make sure you’re using fertilisers in the right doses. A pH outside of the ideal range can also block the absorption of nutrients, causing similar symptoms. Keep the water pH between 6.0 and 6.5. Irrigation can also be problematic. You say you’re watering with 1 litre of water for every 10 L pot, which might be appropriate, but the frequency of irrigation also matters. Make sure that the pots are well drained, and the substrate dries partially between waterings. Dispenser water is normally free from contaminants, but make sure it doesn’t contain too many minerals that can affect the health of your plants.

Hi, I’ve got 2 autoflowering cannabis plants that should grow 60 cm tall indoors, or 1.20 m tall outdoors. I need to grow them in a greenhouse. What should the planting distance be? (Lisa)

To grow your autoflowering cannabis plants in a greenhouse, it’s important to consider both the space that they need to grow properly and the air circulation that’s required to prevent diseases. Given that your plants can reach a height of up to 1.20 metres outdoors, but you’ll be growing them in a greenhouse, a minimum distance of 60 centimetres between each plant is generally recommended. This separation will allow for a good airflow and will prevent plants from competing excessively for light. Having said that, if the space in your greenhouse allows for it, increasing this distance to approximately 70-80 centimetres would be ideal to ensure that each plant has even more room to expand sideways.

I want to grow a single seed of a Kannabia strain. What pot should I use in my 60 x 60 grow tent to get a decent result? It’s in an 11 litre pot at the moment. (Frank)

Using a larger pot, such as 18 or 20 litre, can provide more space for the development of the roots, which can in turn result in a better yield. In a 60 x 60 cm grow tent, optimising the vertical space and maximising the plant’s potential are key to getting a good harvest. With more space to grow, the plant can produce more flowers. But make sure the lighting is potent enough for the size of your plant, because using a high-power LED light that fully covers the 60 x 60 cm area is absolutely essential.

I’m interested in finding out information about the Néctar oil extraction machine. Whether it’s on sale and where to find it. (Julio)

The Néctar machine is an innovative tool developed in Argentina for the extraction of essential oils (mainly those of cannabis). It was created by a group of students from the University of Buenos Aires, and has been designed to be used at home, allowing the production of high-quality oils in an accessible way. Nowadays, the creators of Néctar are at the phase of seeking commercial allies for its manufacture and distribution. To get more information about the availability and the purchase process of the Néctar machine, we advise you to contact the developers directly through the Socialab Community platform, where they have already received numerous comments and questions about the marketing of this device.

And remember…

You can send us your questions about cannabis to ‘Ask the expert’. Each month, we will publish a selection of your questions in our blog, resolving the most important issues.