Winter Growing – changes to your growing style during the colder months.


Winter Growing – changes to your growing style during the colder months.


Autumn is in full swing and winter isn’t far away this blog will look at changes you should make to your grow set up during the colder and more humid months ahead and also things you can do to improve your results during this period compared to growing in the heat of summer.


First let’s think about the current environment it's autumn it's not that cold yet and thanks to the rain the humidity outside is soaring this is great news if you’re in your vegetative period as the need for misters/humidifiers will be less. However if you’re in the flowering cycle then the high humidity could lead to some major issues.

Botrytis (bud-rot) – This voracious mould loves high humidity and reduced air flow, the temperature drops slightly and your exchanging less air, you’re in full swing at the end of flower humidity increases and your large healthy flower heads/fruit are packed in your grow space - the perfect breeding ground for this mould to take hold, it can destroy beautiful rooms in a matter of days if left unchecked.




How do I prevent bud rot?

Adding a dehumidifier such as the Ora 60l/day dehumidifier is a great way to reduce humidity and it can cope with a fairly large room, set you humidity to the desired level and the inbuilt humidistat will control the unit and keep your space at the perfect humidity to help prevent bud rot.  

Increase air flow inside the grow space – anywhere where a pocket of air is stagnant (not moving) within your canopy is a great place for moulds and mildews to take hold. Utilise air circulation fans to keep air moving throughout your room and through your canopy. Lots of smaller fans, or large fans on a low setting, is better than one or 2 big fans on full blowing your plants around too much. You want nice gentle air movement throughout your room so a couple of fans above moving heat away from lights is a good idea and a couple on the floor to circulate the air below– when the canopy is dense in mid flower, point these floor fans up to gently move the air through the canopy and eliminate stagnant pockets of non-moving air.


Temperature – We know plants need to be kept warm for good growth so a good heater is essential for this reason the other reason being a large temperature drop (even if within growing temperature ranges e.g. 28 degrees down to 20) will cause condensation to form between leaves and flower clusters this condensation can cause mould and mildew very quickly, maintaining a night time drop of no more than 5 degrees is the best way to prevent this from happening.  Using a good quality heater such as the Lighthouse 3kw Fan Heater paired with the Lighthouse Wireless thermostat for simple control of your temperature. These thermostats can also be used with our range of oil-filled radiators if you prefer however the dry heat from a fan heater helps to prevent high humidity and the resulting potential moulds.

Regulate watering – Irregular watering and over watering are issues that can increase the chance and extent of bud rot.  Water to no more than 15-20% run off and allow pots to dry back significantly between feeds, don’t leave pots sat in water or water too frequently. Use a good quality timer such as the IWS Dripper Timer for increased control over feed timings and durations in a drip system. Decrease the flood cycles on a flood and drain system, compared to summer.


What do you spray for bud rot?

If you have high humidity or a plant that is prone to botrytis we highly recommend a weekly preventative treatment of Flying Skull Nuke Em combined with the Flying Skull Spread Coat, this awesome product is a great pesticide as well as having awesome fungicidal properties and is great for the treatment and prevention of botrytis and powdery mildew. It’s completely safe and can be used right up until the day of harvest. For infections you can spray this product every 3-4 days.


Use silicon to prevent bud rot

Using a silicon product gives your plants increased resistance to moulds and mildews, ideally start using from the early vegetative stage as a root feed at least once a week is a great way to increase resistance to mould and mildews as well as better growth increased root mass and less stress from heat/cold etc. Also a regular foliar spray is an extra layer of protection, we can’t recommend Grow Genius Mono-Silicic Acid highly enough for your choice of silicon product or if only using small amounts the Buddhas Tree Solar Green Power (also mono-silicic acid) is ideal as the dilution rate is easier for small quantities and is just as effective.


As we get further into winter and the temperature drops significantly these issues become greater so good temperature control is a must, a combination of fan control and adding heat will be essential for good plant growth and big yields.


Day time temperatures (lights on)

Heating to keep your night time temperatures up is done with your heater and it may also need to run during the day (especially with LED grow lights) to keep you temperature optimum for plant growth. However why not take advantage of the cooler lights on temperatures and add some more lighting/supplemental lighting which will add heat whilst having the added benefit of more light=more yield! Win win!

Increasing your main light output such as upgrading from 600w to 1000w grow lights is a easy way to do this or simply add more of the same lighting. Or for increased quality of product you could add some great supplemental lighting such as 315w CDM lights between your existing lights. CDM or CMH bulbs have a great spectrum for increasing yield and quality of your preferred plants, increased essential oil production and better flavour is reported by growers using these lights. You may have to remove them during the warmer months but they are also great as a stand-alone vegetative grow light so you can still use them for the early stages throughout the year.

The other way to control these temperatures without increasing your power usage by adding heat or lights is to regulate your ventilation system more accurately. Use a good quality fan controller such as the SMS single and SMS twin fan controllers for RVK style fans and Maxibright tube fans, or the quieter SMS Hybrid Controllers  or Control Freak Frequency Controllers which can be used on any of our AC fans. Remember though decreasing your airflow will increase humidity as well as temperature making the potential for bud rot higher.


Change to EC fans – EC fans allow even more control of your ventilation system they are super quiet, move loads of air and have fine tuning control thanks to the EC motor technology, the WhispAir EC Fan range represent excellent value for money when purchasing EC fan technology. Also available with a great discount as part of our EC carbon filter kits with either the top value WhispAir carbon filters or for serious odour control the premium Mountain Air Filters.

If your taking your incoming air from outside the building you may want to change it so your incoming air is coming from inside the property this air will generally be warmer and cause less changes in temperature compared to outside air which varies a lot more.


Nutrient levels and feeding

Colder temperatures and higher humidity mean your plants can handle higher nutrient concentrations (EC levels) and their demand for nutrient increases. In warmer rooms you can't give your plants as much nutrient as their demand for water is increased due to higher transpiration rates. Keep an eye on your EC levels in recirculating systems and in your run off if using run to waste drip systems or hand feeding and increase your nutrient strength as required, if the EC levels are dropping it means you can add more nutrients to keep up with your plants demands and achieve a better yield.

Top Tip – if your nutrient EC levels need to be raised a lot do it in small daily increments to not shock your plants allowing them to get used to the increase gradually.


Consider adding Co2 – many growers add co2 in the summer so their plants can handle the higher temperature better and yield more, however in summer you are exchanging lots of air so although it helps with the temperature you don’t get the most from the added Co2 in terms of yield, during winter you can really slow your ventilation system down and with less air exchange your plants can really use the added Co2 effectively as its not drawn out the room so quickly by your exhaust fan. An easy way to add Co2 to your grow space is the Exhale Co2 bags available in two sizes they will last up to 6 months continuous use.



For professional Co2 application consider using either bottled Co2 or a Co2 generator in conjunction with the Ecotecnics Evolution Co2 controller , this allows for a set PPM to be maintained easily accurately. We provide bottled Co2 at our Sheffield store for use with this type of set up.


 Winter is the ideal time to get into indoor growing due to the cooler temperatures and easier to maintain environments you just need to consider the things discussed in this article. If you need help getting set up or optimising an existing set up, get in touch with us anytime we are more than happy to provide advice or even a full consultation either over the phone or in person.

Get set up now just in time for the best indoor growing season!