Winter Growing: changes to your growing style during cold months

Guide to Growing Indoors in Winter

Autumn is in full swing and winter isn’t far away. This blog looks at changes you should make to your grow room set up during colder months and things you can do to improve results during this period. 

We’ll also look at some steps you can take to prevent bud rot issues and discuss products that can keep your growing environment perfect in winter.

Protecting Your Plants from Bud Rot

To protect your plants against bud rot, we first need to look at your growing environment

It’s autumn now, and not yet that cold. But thanks to the rain, the humidity outside is soaring.

This is great news if your plants are in a vegetative period as you won’t need to use humidifiers or misters as much.

But, if you’re in the flowering stage, then the high humidity can cause major issues, including bud rot.

What is bud rot?

Botrytis (bud rot) is a voracious mould that thrives in highly humid conditions with reduced airflow.

Right now, the temperature has dropped slightly so you’re exchanging less air in your grow space. 

If you’re in full swing and approaching the end of your flowering period, the humidity increases and your large healthy flower heads/fruit are packed in.

This provides the perfect breeding ground for bud rot to take hold and it can destroy beautiful rooms in a matter of days.

How do I prevent bud rot?

There are a few things you can do to prevent bud rot from taking hold of your plants.

  • Control Humidity

Adding a dehumidifier such as the Ora 60l/day dehumidifier is a great way to reduce humidity in your grow space and it can cope with fairly large rooms.

Set the humidity to your desired level and the inbuilt humidistat will control the unit to ensure your space stays at the perfect humidity to prevent bud rot.

      • Increase Airflow

Moulds and mildew can take hold where pockets of stagnant (unmoving) air collect in your grow space.

You can combat this by using an air circulation fan to keep air moving throughout your grow room and canopy.

You want gentle, consistent air moving around the room, so it’s better to use several small fans, or large fans on low settings, rather than blowing around your plants too much. 

You can place fans above the canopy to move heat away from the lights and put a couple on the floor to gently circulate the air below. 

When the canopy is dense in mid-flower, point your floor fans up to gently move the air through the canopy and eliminate stagnant pockets of non-moving air.

Regulate Temperature 

To ensure good growth, it’s important to keep your plants warm. So adding a heater to your grow space is essential for keeping the temperature regulated.

Heaters can also help you in avoiding detrimental drops in temperature. Even dropping from 28 to 20 degrees can cause condensation to form between leaves and flowers, which can lead to mildew and mould issues.

To avoid this, you can enlist the help of good quality heaters to make sure your nighttime drop is no more than 5 degrees.

For instance, pairing the Lighthouse 3kw Fan Heater with the Lighthouse Wireless thermostat give you simple but effective control over your grow room temperature.

You can also use these thermostats with our range of oil-filled radiators. However, the dry heat from a fan heater helps prevent high humidity and the resulting moulds.

  • Regulate Watering

Another cause of bud rot is irregular and overwatering your plants.

When watering, ensure there’s no more than 20-25% runoff and allow pots to dry back significantly between feeds - don’t let pots sit in pools of water or water too often.

You can use a good quality timer, such as the IWS Dripper Timer to increase your control over feeding times and duration in your drip system. 

And, you should decrease the flood cycles on a flood and drain system, compared to summer.

What spray can I use for bud rot?

If you have high humidity or a plant that's 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 and has excellent fungicidal properties, delivering effective treatment and prevention of botrytis and powdery mildew.

It’s completely safe and can be used right up to harvest. And 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 bud rot and other moulds and mildews.

Ideally, you should start using silicone as root food at least once a week from your plant’s early vegetative stage.

It’s a great way to build resistance to mould and mildews, and promotes better growth, increased root mass and reduces stress from heat/cold etc.

Furthermore, using a regular foliar spray provides an extra layer of protection to your plants.

We can’t recommend Grow Genius Mono-Silicic Acid highly enough for your choice of silicon product.

Or, if you’re 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

This means good temperature regulation is a must, and adding a combination of fan control and heat is essential for good plant growth and big yields.

Winter Day Time Temperatures (lights on)

You can keep the nighttime temperatures up in your grow space by using a heater. You may also need to run it during the day (especially with LED grow lights) to keep your temperature regulated for optimum plant growth

However, you can also take advantage of cooler lights-on temperatures by adding more lighting/supplemental lighting.

This will add both heat and light to your grow space, resulting in a better yield - win-win! 

Increasing your winter grow lights

You can easily increase the main light output in your grow space by upgrading from 600W to 1000W lights. or by adding more of the same lighting.

To increase the quality of your product, you can add great supplemental lighting in between your existing lights, such as 315w CDM light.

CDM or CMH bulbs have a great spectrum and help you achieve:

  • Yield and quality of your plants
  • Increased essential oil production
  • A Better tasting end product

Although you may have to remove them during warmer months, they provide a great stand-alone vegetative grow light so you can still use them for the early stages throughout the year.

Regulate temperature without increasing power

Another way to control the temperature in your grow room without increasing power usage or heat is by accurately regulating your ventilation system.

For RVK style fans and Maxibright tube fans, start by using a good quality fan controller, such as the SMS single and SMS twin fan controllers.

Or for quieter options, try the SMS Hybrid Controllers or Control Freak Frequency Controllers, which can be used on any of our AC fans 

It’s worth remembering that decreasing your airflow will increase both humidity and temperature, increasing the risk of bud rot.

Change to EC fans

EC fans give you even more control over your ventilation. Not only are they super-quiet, but they move lots more air, and the EC motor technology provides fine-tuning controls.

The WhispAir EC Fan range is excellent value for money and comes with a great discount when bought as part of our EC carbon filter kits.

These include top value WhispAir carbon filters, or for serious odour control, the premium Mountain Air Filters.

Another thing to consider; if you’re bringing air in from outside the building, you may want to change it so the air comes from inside the property.

This air inside is generally warmer and causes fewer temperature changes compared with outside air, which varies a lot more.

Nutrient Levels and Feeding in Winter

Colder temperatures and higher humidity mean your plant’s demand for nutrients increases and can handle higher nutrient concentrations (EC levels).

However, in warmer rooms, you can't give your plants as much nutrient as their demand for water increases due to higher transpiration rates

Make sure to keep an eye on your EC levels in recirculating systems and in your runoff if using run to waste drip systems or hand feeding. Then, 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 better yields.

Top Tip – if you need to raise the nutrient levels a lot, do it in small daily increments so they get used to the increase gradually. Otherwise, you can shock your plants and stunt their growth. 

Consider Adding Co2 to Your Grow Room

In the summer, many growers add Co2 to their grow spaces so their plants can handle the higher temperature and produce better yields.

But the increased airflow in summer grow rooms means that more air is exchanged. So, although it helps with the temperature control, 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 occurring, your plants can really use the added Co2 effectively.

This is because the Co2 remains in the room longer, rather than getting drawn out 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 of continuous use.

And for professional Co2 application, consider using either bottled Co2 or a Co2 generator in conjunction with the Ecotecnics Evolution Co2 controller, letting you easily set and maintain Co2 levels.

We provide bottled Co2 at our Sheffield store for use with this type of set-up.


Winter Growing: final thoughts 

Due to the cooler temperatures and easier to maintain environments, growing in winter is the ideal time to start growing indoors. 

Before you start, consider the factors mentioned above so you can avoid bud rot and other serious mould and mildew issues.

If you need help getting set up or optimising an existing set up get in touch via phone, email or our Instagram and Facebook channels.

We’re more than happy to offer advice or even a full consultation over the phone or in person.

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