It's that time of year again. Temperatures spike and grow rooms overheat. If your grow room's getting too hot, here's what you can do.

Your lights kick out the most heat in your grow room. Unless you want to cook your plants, follow these tips:

This is the coolest time of day! Since fans don't have to work as hard, running costs should drop.

Lots of growers like switching to LED lights or CDM lights in summer - we ran a test and found your room will run a few degrees lower by doing this.

If you don't want to swap out your HIDs, use an air-cooled light (like the DARKSTAR). 

Keep them (and the heat they produce) outside your grow room. 

Dimmable ballasts are digital. Digital ballasts already emit less heat than magnetic ones running at full power. To reduce heat output further, they'll dim lights right down to 250W.

Lights are a big source of heat - raise them up and away from your canopy if your grow room gets too hot. 

If worse comes to worst, remove a light! Don't forget, you'll need a LightRail to increase coverage from remaining lights.

The obvious thing to do is to extract more air. You can also:

With a speed controller, fans will automatically speed up when your grow room needs cooling. 

If the air outside your grow room is hotter than the air in it, first make sure you're drawing air in from the coolest place inside your property. If nowhere is cool enough, you might need to switch intake fans off.  Otherwise you'll just be heating your grow room further. 

Replace your carbon filter at the start of summer so pressure drop is at its lowest. At the very least, replace the carbon filter sleeve to reduce dust build up resistance.

This streamlines your airflow. Make sure you use metal bends rather than depending on twisted ducting. 

Buy a fan that's more powerful than you need it to be. Then in summer, you've got room to speed it up when you need to. In winter doing this should reduce running costs if you use an EC Controller or Control Freak as fans don't have to work as hard to cool your room.

A small Black Orchid fan can be used to suck hot air away from appliances. Even if the appliance is outside your tent, you still want to cool it, otherwise you'll be warming intake air. If the appliance is in your tent, duct any hot air through a carbon filter. If it's outside your tent, duct straight out of your window.

To help stop hot microclimates forming, use air circulator fans. 

Point them at anything that gets hot - like chillers, lights and ballasts.  Even if the appliance is outside your tent, it'll still be warming intake air - make sure you cool it. If circulator fans aren't cooling it enough, use an inline fan to duct air through a carbon filter or out of a window. 

Some of our low profile options will help you get at nooks, crannies and corners. Otherwise they'll become very hot and humid - a breeding ground for mould. 

If you point them directly at the tops of leaves you can cause windburn. The DiffuseAir is great for preventing this. 

Remember how photosynthesis works?

Light + CO₂ + Water = Energy

If plants have the light and water but not the CO₂, they can become stressed. 

Add CO₂ to ensure photosynthesis can continue at a really high rate. This'll increase growth and help plants cope with high heats of up to 29^oC - 30^oC. 

The best bit is that high temperatures actually improve CO₂ absorption - it's a win all round. 

Exhale CO₂ Bags and TNB CO₂ Dispersal Cannisters are great options for first timers. They’re easy to use, very effective and completely safe in all conditions.

In general , as your temperature goes up, so should your humidity. A higher humidity helps:

• Prevent over transpiration (where plants lose too much water through leaves)
  
  
• Bring your temperature down (2 - 3^oC avg)
  
  
• Keeps the stomata on leaves open (great for photosynthesis, which relieves heat stress)
  
  

• Slow rate of pests breeding  

If using an RAM Humidifier, you can fill it with ice cubes of freezing cold water to help reduce temperatures.

In summer, you need to really keep a close eye on your feed - especially if you have a hydro system where roots are naked and exposed.

The easiest way to keep your nutrient cool (18^oC - 21^oC) is with a nutrient chiller. It acts as a mini refrigerator.

In summer, as plants use more water, your feed becomes too concentrated, which can cause overfertilisation. 

Keep a close eye on your pH & CF.  If your feed becomes too concentrated, add some water.

Use it from the start of your grow and plants build up a heat resistance. It'll help plants prosper in conditions up to 40^oC!

Other boosters & additives, like SHOGUN Sumo Active Boost and SHOGUN Silicon also help reduce heat stress.

If your nutrient temperature becomes too warm, root diseases can take hold. To kill 99.99% of root diseases, add Silver Bullet Roots to your tank. A small dose with every tank change is all you need.

Another quick win is RhizoLine Pipe, which can reduce your nurient temperature by 3^oC - 8^oC. 

To stop your feed being warmed by lights, cover your tank and pots. The Correx cover you get with NFT systems is great for this. Otherwise, use reflective sheeting (shiny side up)! 

Silicon additives thicken stems, leaves & branches to lock in water. As a result, plants are better able to cope with climate extremes. SHOGUN Silicon and Emerald Harvest Sturdy Stalk are both silicon additives.

Biobizz Leaf Coat isn't a Silicon, but works in a similar wat. It coats leaves in a latex layer that helps prevent water loss

Both Sumo Boost and Sumo Active Boost help relieve heat stress when used as a foliar spray

All SHOGUN Base Nutrients contain SmartZen. It's an exclusive additive that helps plants cope with heat stress by reducing the rate of transpiration

The main problems you get in propagators during summer are caused by your temperature or humidity.

Temperatures over 27^oC will start to cause issues.

To keep your propagator cool, don't overdo it with your lights. Raise your light height if you need to. You can use ice packs to cool your nutrient solution in an Aeroponic Propagator. 

If using a heated propagator, think of putting it on a timer. 

Too much moisture is a big cause of failed rooting. Aim for a humidity of 70% - 85% RH and make sure:

• Rooting cubes aren't too wet
  
  
• No water or solution is in the propagator tray
  
  
• Only a light mist of moisture is visible on the propagator lid (no droplets!)

Don't forget to make sure there's always enough nutrient solution or water in your propagator. 

During summer, pests breed quickly! And they love the dry and hot conditions in your grow room - especially spider mites. 

You don't need to do anything drastic. A lot of it is just common sense - like preventing cross-contamination and checking plants.

Scout for pests more often - every 3-5 days should do the trick.

• Hang Horti-Shield Yellow Sticky Insect Traps
  
  
• Check leaves closely using an Active Eye Magnifier
  
  
• Keep an eye on your rootzone

• Use Spider Mite Predator Sachets 
  
  
• Attach Bug Blockers to intake ducting
  
  
• Never draw air in from outdoors
  
  
• Don't use anything from someone else's grow room
  
  
• Sterilise your grow room between crops
  
  
• Use a humidifier to slow pest growth
  
  
• Point circulator fans at rootzones to slow Fungus Gnats right down

If you're really struggling, try a taller tent.

The standard tent size is 200cm tall, but you can easily get a 215cm in your home. That extra 15cm of headroom will really make a difference.