Ask the expert: power cuts, untimely pruning, slippery sex, and much more

We present a new instalment of our compilation of questions about cannabis that growers send to our Kannabia team of experts. On this occasion, there’s a little bit of everything: plants that go too far during their vegetative period and grow as if there was no tomorrow; pruning of autoflowerings that contravenes the typical line of thought; yellow leaves that emerge everywhere… And even whether it’s advisable to use cannabis butter on your nether regions, in the style of the Last Tango in Paris. We have answers for everyone, so remember to send us your questions (regardless of how crazy they may seem) so we can treat them with all the affection they deserve. So let’s begin!

1- We’re growing CBD and THC in a greenhouse in Colombia, and we want to grow a hemp crop in an open area on the same farm. What’s the minimum distance that we need, and what would be the implications for my THC and CBD grow? (Gene Fernando)

Blessed Colombia, land of strong August winds! To grow hemp near a THC and CBD crop without risk of cross-contamination, a minimum distance of 3 – 5 kilometres is recommended (although this should ideally be even higher in windy areas). Hemp pollen is extremely light and can travel long distances to inadvertently fertilise THC and CBD plants, significantly reducing their cannabinoid levels. It is also important to consider that some pests and pathogens can move between nearby crops. Lastly, when planning both hemp and THC/CBD grows in the same area, it is advisable to have well-differentiated flowering periods between them to help minimise the risks.

2- I changed the photoperiod from 18/6 to 12/12 three weeks ago to get my photo-dependent plant to flower, but now I’ve just realised that it’s an autoflowering. Can I go back to 18/6? (José Jiménez)

If you’ve got autoflowering plants, going back to an 18/6 light cycle is not only safe but it’s almost a necessity. Unlike photo-dependent strains, which need a decrease in the photoperiod to flower (such as 12/12), autoflowerings grow and flower according to their own ‘internal clock’. Therefore, with an 18/6 cycle (or even 20/4), you’ll be maximising the hours of light, thereby helping the plants to develop a greater vegetative mass and produce denser flowers. Keep an eye on the temperature in the grow, as more hours of light translates into more heat. Also bear in mind that you’ll be causing them some stress.

3- I’m growing Colombian Jack seeds and I suspect that I’m failing with some of the parameters. Perhaps overwatering… And another thing that worries me is air renewal… How can I recognise symptoms of lack of air or over-ventilation? (Maximiliano Gabriel)

Poor ventilation in a cannabis grow can cause serious problems such as slow growth, yellow leaves, and an increased risk of pests and fungi due to the accumulation of moisture in the denser areas of the plant. On the other hand, if you have excessive ventilation, you may notice that the leaves dry out, bend, or even become brittle and worn on the edges, since the constant wind can stress the plant. The key is to maintain a smooth air circulation, so that fresh air is constantly entering the grow area and warm air is expelled. Make sure to use oscillating fans, adjusting their speed according to the size of the grow and the stage of growth of the plants.

4- These last few nights, when my lighting is on, I’ve had power cuts for about 2 – 3 hours. My plants are now foxtailing in their seventh week of flowering. How can I fix this? (Medard)

Foxtailing occurs when the buds develop an elongated and not very compact shape. This is commonly caused by light fluctuations and thermal stress. In the seventh week of flowering, any interruption in the light cycle can alter the formation of the buds, as you’ve experienced with your power outages. To reduce the impact, you could install an electrical backup system (i.e., a generator), although this may be a far-off option for some. Watch the trichomes and pistils, as they will be the best indicators of maturity – if you notice a sudden change in their colour, it could be a sign that stress has affected their ripening.

5- Hi guys, do you recommend pruning the strain Gnomo? If so, could you tell me what’s the best time to do it? I’m actually working with LST on this plant. (Tanio)

Gnomo is an autoflowering strain, and these plants usually don’t respond well to pruning because their shorter life cycle puts a limitation on how much time they have to recover from any kind of stress. Having said that, if you’re well versed in advanced growing techniques, this won’t pose any challenge for you. However, Low Stress Training (LST) can be implemented without too much trouble, by gently bending the branches to better distribute the light and maximise its exposure to air. The best time to apply LST is during the first weeks of vegetative growth, before the plant starts flowering, so that it can adapt to the training and grow in a uniform and impressive way.

6- My outdoor plant is growing bulky and tall. Now it’s 2 m high, and quite bushy, with a stem with a diameter of about 3 – 4 cm; it’s really strong. However, I can’t detect any male or female characteristics. The plant’s been in the garden for 4 months. What sex is it more likely to have? (Jürgen Mittmann)

Since your plant is 4 months old and still isn’t showing any sexual features, it is likely to be a photo-dependent strain in the vegetative phase, given that these need a reduction in the hours of light to start flowering – a change that usually occurs naturally towards the end of summer. The plant will probably continue in the vegetative phase until the natural photoperiod decreases to about 12 hours of light, which usually happens in autumn. If you’re in a region with a stable light cycle, you can force the flowering by covering the plant to simulate a longer night. Another possibility is to observe the nodes on the branches while waiting for the natural flowering – when the time comes, small pre-flowers will appear on them, indicating whether it is male (horror, pollen sacs!) or female (i.e., wonderful whitish pistils).

7- Hi, I hope you can help. One of my two Russian Dolls is getting yellow spots on the leaves, and I don’t know what it could be or how to treat them. (Florián)

Yellow spots on the leaves of Russian Doll may be caused by several reasons, with nutrient deficiencies being the most common causes, especially when there’s a lack of nitrogen, magnesium, or iron. These deficiencies are usually translated into spots that start on either old or new leaves, depending on the nutrient, and then expand if the nutrient plan or pH is not corrected (check that the pH of the soil or the irrigation water is between 6.0 and 7.0 to ensure that nutrients are available). If the spots are irregular or have edges, you may also be dealing with a pest like spider mites, which leave small bites. Apply specific fertilisers if a deficiency is confirmed, or an organic pest treatment if you find those annoying bugs.

8- What effect would cannabis butter have if used as a lubricant? (Miriam)

The use of cannabis butter as a lubricant is not recommended, because it’s incredibly fatty and can alter the bacterial flora of the intimate areas, causing irritation (although we haven’t tested it yet, but who knows what can happen!). Besides, cannabinoids may produce psychoactive or sedative effects that are not always desirable for intimate use… And, to top it all off, its absorption in this area still hasn’t been widely studied. For this type of application, it is safer to opt for water-based commercial lubricants, or products specifically formulated with non-psychoactive cannabinoids that are designed for use in these sensitive areas, minimising the risks of irritation or infection.

9- My Amnesi-K Haze seems to have started a second flowering. The pistils that formed at the beginning are now brown, and completely new ones are coming out. Most trichomes are still clear, but now they’re also getting a little milky. Doesn’t it flower for at least 9 – 10 weeks? I‘m not exactly sure. (Ingo)

Amnesia Haze is known for being a long flowering variety, usually between 10 and 12 weeks, so it is common for it to develop a second layer of pistils in advanced stages. This phenomenon usually occurs when the environmental conditions change slightly, or when the plant perceives that it has more resources to continue flowering. Watch the trichomes as the main indicator of maturity, and make sure that the plant has proper nutrition and a stable photoperiod, since any sudden changes can prolong the flowering and affect the final yield.

10- Hi, I have a Hellfire OG that’s in bloom, but still hasn’t got a large main cola. What’s the maximum time limit for harvesting? (Majurel)

Our Hellfire OG has a flowering time of between 8 and 10 weeks, so use that time frame as a guide. The main cola may not fatten considerably in some varieties, depending on their genetics and the growing method. We reiterate: the best guide for harvest is to watch the trichomes – if most of them are milky, and some begin to turn amber, you are at the optimal point of harvest. If the flowers are small, consider a slow drying technique to maximise the potency and flavour of your buds. Avoid waiting too long after this point, as the amber trichomes indicate a more sedative effect and a possible degradation of quality. Bon appetit my friend!