SAS in a windowsill

Ask Percy: Sativas on a UK windowsill

This week we have some questions concerning a couple of sativas on a UK windowsill. Briz writes.

Hi Percy,

I didn’t know when to start so have two little plants on the go already. I planted 1 x Moby Dick and 1 x Haze 2.0, both feminized autoflowers from Dinafem, at the beginning of April and they broke through the soil on April 10.

They seem quite small/slow for two weeks growth from what I’ve been reading. They only have one and half sets of proper hemp shaped leaves, and are about 6 inches tall. Although they seem quite happy and healthy is a south facing window in the South of the UK.

I don’t think they’ll triple in size in a week, and I’m concerned that they wont grow enough in veg to yield anything, considering I’ve been reading that many autos start to flower in 3-4 weeks.

Did I start to early?

Also, I have a small greenhouse but it’s still quite cold in the evening, too cold for my chillies! Would you recommend taking them out to the greenhouse where it gets up to 30C in the day, and then bringing them in in the evenings?

Thanks for your help and for the great site. I stumbled upon it tonight and it’s exactly what I was looking for. Just the kind of relaxed “try and see” approach I’m taking to my humble little home grow. Cheers!

Thanks Briz for the great questions. I very much appreciate the kind words and it seems that you are exactly the kind of grower the site is aimed at. There’s a few points I’d like to address here.

Strain choice
I notice that both the strains you are growing are sativa dominant.

In their nature sativas are taller and more prone to stretching, even in good lighting conditions. Growing in the tropics, they have adapted to a steady, strong sunlight and pure sativas can reach very tall indeed. I still managed to grow out an autoflowering sativa under a sunny skylight but never seemed to get the same results I did with an autoflowering indica in the same conditions (see the picture below of a Big Buddha SAS grown under a skylight – needless to say I now stick to indica dominant strains). That said, don’t give up you should still get these babies to flower and learn a lot in the process. You can still get nice head highs from indica dominant strains if that was the reason for your choice.

Sativa under a skylight
Big Buddha SAS grown under a skylight. Stretch can be seen by the long inter nodal lengths.

Maybe start of April is a little early in the UK. I have this psychological thing of always germinating around April 20. Then I always reflect, thinking that I started too early. In fact, I’ve started plants at this time and then another in May and they both finished around the same time. Trouble is, you see the weather getting nice and spring is in the air and it’s just too tempting not to start.

The plants will start to flower when they are ready to do so, so no need to worry about how long it’s taking to produce leaves or pre-flowers. It sounds like you are experiencing stretching as the plants search out light. Try and keep them in the sun as much as possible, support with a wooden stick if necessary or even add more soil around the base to help them not to flop from being too top heavy. When the plant is bigger bamboo canes are useful to keep it from falling over.

Autoflowers do start to produce flowers quite early but will keep growing once they do so. We’re not producing a cash crop here so be patient and appreciate the learning experience along the way – if you get to smoke a few grams at the end then it’ll be the greatest reward ever. It took me a few seasons growing and hours of reading, forum trawling to get good results in a windowsill so hang in there.

Sativa buds grown under a skylight
The same SAS plant as buds are starting to form

When you are growing on a windowsill, under a skylight or on a balcony you can completely disregard the claims of timing when buying seeds. These times are based on ideal growing conditions, for example a professional greenhouse in Spain or indoor grow op. The plant will be ready once it is ready, it might take till September or it might finish in late July but until the trichomes are giving signals that it’s time to harvest then you have to wait for mother nature to do her thing.

You say you have a greenhouse. This will definitely help matters. To get good results you’d be hoping for 6 hours of full sun on the plants. In a windowsill it’s tricky, even if it is south facing. As the sun moves through the sky the light will move through your room. In a greenhouse this is less likely to happen. If you can keep the temperature under 30C that’ll help the plant to grow. Much higher than that could stunt growth a little. A simple fix would be to open a window on very sunny days or if budget permits to setup an extraction fan to expel the hot air and pull in cooler air from outside. You can even get these with temperature controllers to activate when it’s too hot. I wouldn’t leave the plants in there during the night until the temperature stays above at least 12C. Depending on your pot size these sativas could get quite tall, 1 metre plus in a 10 litre pot so you might not be able to move so easily each day.

Growing medium
Another thing worth mentioning but not covered in your comment is the growing medium, you say “soil”. It’s important that the roots have plenty of air around them and are able to dry out a little after each watering. This can be achieved by mixing in perlite and coco husks to create the air pockets the plant needs. Solid potting compost or soil direct from the garden won’t work so well. Another aspect to consider is how the plant will be nourished. It needs food to grow. If the soil mix has compost, or other natural fertilizer then the plant should have everything that it needs. If not, you may need to boost it with fertilizers. You can get bio fertilizers for “soil”, just use half the recommended dosage, give the plant a rest every few feeds with pure water and don’t forget to flush at the end.

Very finally, if you can test the pH of the water you are giving the plant this would be a good thing to discover. You’re aiming for around 5.5-6.5. The right pH allows the plant to take in the correct amount of nutrients from the growing medium.

I hope this information helps. Briz definitely has the right attitude so that’s 90% of the job done.

If you’d like to have your questions featured in “Ask Percy” please just add them as a comment.

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11 thoughts on “Ask Percy: Sativas on a UK windowsill”

  1. For windowsill hydrophonics setup what nutrients would u recommend and when to use. Thank you

    1. The only nutrients I’ve had experience with for the windowsill hydro grow is advanced nutrients. It worked fine for me. I’m afraid that I haven’t compared brands so am not in a position to endorse or not. You use so little on one plant I still have most of the bottles left after a few seasons! Whatever you buy make sure you store it correctly in a dark, cool and dry place. For the moment I’m more experimenting with all organic grows in soilless mix. This would have been my preference from the start but sometimes you have to compromise when conditions are not right. Hydro is much better suited to “indoor” growing on a windowsill and it seems that there are no bio solutions on the market (at least not when I last checked) that you can use on hydro. All the best Percy

    1. Hi, thanks for the kind words. I hope you find something useful here. All the best, Percy

  2. Hello Percy, one question I haven’t seen addressed on this site:

    How do you conceal the smell?
    Since this is window sill growing then I guess you can’t pass the air through a filter or something.

    I have people coming to my house for meditation twice a week. If I go for window sill growing how do I conceal the smell? Thanks.

    1. Hi Avillax, thanks for the great question. I’m afraid there’s not much to do about the smell. My technique had always been to keep it as far away from where guests would be as possible but depending on the layout of your place it’s not always gonna work. The smell will be at its peak for about the final month. When it was close to harvest the smell hit you coming through the front door and the plant was on the third floor! I just tried to avoid non 420 friendly guests during that time. Now I grow in a small lean to greenhouse in the back yard as it’s not possible to grow in my current house for a few reasons (smell being one of them). I wonder if burning incense sticks might help? Sandlewood is nice and the musky smell should help mask the pot smell. I just hope your fellow meditators are not sensitive to the smoke. You could try making a wooden frame with 2″x1″ wood and long screws to hold it together. If you make a snug fit to the walls and ceiling you can put it in place without drilling into the walls or floor, use draft excluder foam stuck to the wood to make the fit more snug. Then you could cover it with thick transparent plastic. This should help reduce the smell coming from the plant and allow the light to pass through, whether this is a practical thing to set up or not would be for you to decide. I did a similar thing and even made a door with hinges on so I could get in there. I hope this helps, good luck with it all, Percy

  3. Hi Percy, also another thing: I’m in Czech Republic which is sunnier than the UK, everybody tells me window sill doesn’t work, I don’t care about yields, I have a very small consumption like 2 grams per month.

    I just want a variety that can be grown on window sill, with low smell so I dont have to invest on filters and which gives me the effects of being euphoric, happy, social, giggly, uplifted and AVOIDING many thoughts and very active mind, hallucinations, paranoia, etc. I was told Blue Mystique was a good choice, what others do you recommend? Can window sill growing deliver this qualities in the resulting plant?

    1. Hi, yes for sure it can give you buds as good (if not better) than those from a coffeeshop. I say better as you know exactly what went into it. I had the same when I was growing, people say it’s not gonna work. I persevered and have always been happy with the end result. At the end of the day you are not growing for them, you’re growing for you. It may take a couple of seasons to get the hang of it but if you can get the right sunny spot you’ll be smoking very nice pot for pennies :) In CZ you’re gonna get good results. I would stick to autoflowering as you’ll struggle to control the light for photoperiod plants and they get stressed and produce male flowers and end up filling your buds with seeds (which may not be a bad thing as you’ll have some free seeds for next grow). I’d not come across Blue Mystique but it sounds awesome! Blueberry and Northern lights are my favourite strains so a combo of the two should be very nice. Not sure if it comes in auto though? I know you can get Auto Blueberry and Auto Northern Lights. Blueberry has great medicinal qualities and a very nice euphoric happy high. NL has a trippy and creative high followed by a very soothing body stone that is great for those suffering from insomnia. In fact just writing about it makes me want to go smoke some! I hope this helps, happy growing Percy

  4. Thank you so much for your motivation Percy. And you’re growing in the UK, my brother lives in London and complaints that the skies are always dark but you can still grow marijuana!!! So I guess I can grow even better in Czech Republic. I’ll try to get Blueberry too, Blue Mystique is supposed to come from Blueberry and they also sell them in auto and feminized. Like I said, I don’t care about the yields, even if they stress and start producing seeds can they still produce some buds? If the answer is yes and the quality of the weed doesn’t get affected then it’s totally worth it and almost free!

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