Whether you have an indoor grow room, a greenhouse or even a few grow shelves, there are some very specific things that you need to stay on top of or things can go wrong very quickly.

With the popularity of indoor growing… growing, I thought it was important to share the key things to manage in your enclosed growing space to prevent failure. Also, stick around until the end, I will share with you a big failure I recently had.

Indoor Growing Room Challenges

Often gardeners think that once they have a greenhouse or indoor grow room that its a panacea for all their gardening woes. The pictures on the internet and social media with the fancy grow lights, shelves and big harvests make it look like everything is going to work perfectly without any extra care and attention.

It’s not all doom and gloom either but you definitely don’t want to let your guard down as I did. Before I dive into the very real potential issues you could face and I tell you where I went wrong, let me say that I do LOVE my indoor grow room. The reasons why are a long list and I will save that for another day. As we see so much of the successes online I thought it very important to shine a light on the other side so you can grow indoors without any illusions.

Enclosed Growing Spaces

It’s important to know that this applies to any enclosed growing space such as a whole room, a greenhouse or those little grow tents you can get. I’m speaking to the average home grower here who has a small, simpler set-up not a big commercial grower, they have invested big money to solve the below issues.

Greenhouse & Indoor Grow Room Issue #1

Ideal Grow Room & Greenhouse Temperature

The ideal temperatures for a grow room. Greenhouse is in like the 18C to 24C range.

When the sun hits your greenhouse, your temperatures are going to absolutely skyrocket. Without opening the door, or vents you can cook your plants very quickly. On a really warm sunny day you may even need to take your plants right out of your greenhouse if you can’t vent it properly.

In my case, the furnace coming on in the morning to warm up the house also increases the temperature in my grow room very quickly. Add in grow lights that can throw off heat (a few of mine are regular T8 and not LED) and you increase the temperature even more.

The opposite can happen as well. If you’re growing in your basement (like I am) it is often much cooler. You can either keep the house temperature higher (with the current energy costs who wants to do that), or get yourself a little space heater to keep the night time (or even day time) temps from dropping too low.

My preference is a radiant or infrared heater like the ones below. They are not as drying as a simple coil with a fan. I have crisped my plants on more than one occasion with one of those and so not a fan! (pun intended 😉 ) 

Purchase a quality thermometer / hygrometer to give you a very clear understanding of where your temperature is at and how it fluctuates through the day. 

I purchased this simple multi-zone thermometer / hygrometer combo. It works amazing. I keep the main display on my kitchen window sill so I see it often. It tracks the high & low temperatures of the day. I can place the different sensors around my house, my greenhouse and even in my low tunnels. Without this tool you have NO IDEA what your temperatures are doing. This is a must for growing in an enclosed space.

This is the multiple room thermometer I use. You can find it by clicking this link here.

Greenhouse & Indoor Growing Room Issue #2

Your humidity. The more plants you get growing in a space, the more transpiration you have. You have humidity in your soil and likely some water sitting in trays. This means a lot of humidity overall. Your plants for the most part like this and need this… but there is a fine line. Especially in your house where you could cause mold issues. This is also where your thermometer / hygrometer is a very important tool.

When growing in your house keep your humidity below 60%. I shoot for just below 50% which gives me room for it to fluctuate. You will find after you water everything that your humidity will jump quite a bit. Above 60% is the danger zone for mold growth. 

I use a dehumidifier to keep my humidity in check. I strongly recommend this for growing in your house. 

In a greenhouse environment you have more freedom. The ideal humidity is about 80%. Plants do grow at their best around this temp, but you cannot let this happen in your house or you risk major mold issues.

Greenhouse & Indoor Grow Room Issue #3

The third thing is airflow. Air movement keeps fungal diseases from having an easy time settling in. Keeping the leaves and stem moving in a gentle breeze is essential for preparing them for the outside world as well. You don’t want your precious seedlings and transplants to snap in half the first time they feel wind.

In an indoor grow room you will need at least one fan. Depending on your set-up you may need more. I use a combination of a larger tower fan to move air around the whole space and also a little clip on fans to direct into some of the harder to reach places.

These little plug-in clip on fans are my favourite. Super easy to add almost anywhere. You can find it by clicking this link.

My Indoor Growing Room Fail

So where did I go wrong?

Everything was going perfectly. I was so confident that I had set everything up perfectly that I let my guard down big time. I was watching my temperatures and humidity very closely.

#1 Temperature

My first error was assuming that the room was holding a consistent temperature without the help of my little radiant space heater so I turned it off. My night time temperature started dropping too low (I like the house cooler while we sleep). I discovered that I was hitting often 14-16 degrees at night which is not ideal. It’s just a little bit too cool for heat loving plants like tomatoes.

#2 Humidity

The quantity of plants was really starting to increase. When this happens your humidity also rises. That combined with cool night temps is a bad situation.

#3 Airflow

I did not have enough fans going for the amount of plants I had accumulated by that point. I was only using my tower fan on it’s lowest setting and had not yet turned on any of my little clip on fans.

These 3 items above created the perfect storm for fungal diseases to set in.

#4 Cold Water

To further exacerbate the problem, the little handheld sprayer that I set-up in my basement was drawing from our very cold well water. Unfortunately, I have no way to adjust the temperature on it. 

#5 Moisture On Plant

The sprayer also creates a bit of a mist when watering. This naturally gets on the plants themselves.

The Result

I invited in either fusarium wilt or verticillium wilt to my tomato plants. The symptoms are nearly identical so I can’t say for sure without lab tests. Either is very bad news.

If you are new to tomatoes you will discover at some point how fussy they really are when it comes to disease, temperature and watering. They really keep you on your toes… but they are so dang good!

Hindsight Always 20/20

If it wasn’t for experiencing this several years back I may not have caught it so soon. I was growing down in my basement (not in a room) without being able to control the temperature and the same thing happened. 

How To Deal With A Fungal Disease In Your Grow Room

Most fungal diseases are very contagious, there is no cure and you have to be ruthless. Discard every plant that is sick and all that are touching it. Sterilize your trays, containers, tools, sprayer, shelves, you name it. 

Thankfully I didn’t have it touching a bunch of other plants. Don’t hesitate if you discover something is amiss. It sucks to toss some plants, but it really sucks to toss ALL your plants.

Recipe For Disaster

I was not being as cautious as I should have been. Between the sprayer getting moisture onto the plants, the water temperature being pretty cold, the temperature dropping at night, the overall like humidity levels, not enough air flow, it was the perfect environment to invite disease to my tomato plants.

It’s not fun. Whenever we see things going wrong with our plants, we can sometimes go into denial and pretend like nothing is wrong. This is the worst thing you can do. It will get so much worse if you don’t address it immediately. 

The good news… I managed to stop the spread and did not end up losing all my tomatoes as I thought I might. I was ruthless and anything sick got tossed immediately. 

There are lots of local greenhouses and growers that I can go and support with my business to top up my tomatoes for the summer and all will be well.

Be Cautious!

Hopefully you can learn from my lesson. Don’t let your guard down because things can go wrong very quickly. 

This can happen to anyone. It is also a very valuable learning experience when it does. If it happens to you, take action immediately and move on. You are not a failure as a gardener. Growing indoors or any enclosed environment is not how mother nature does it. It is a precarious thing we are doing trying to be mother nature and it doesn’t always work.

Always practice gratitude for the wins, and the lessons! It’s how we grow (all the puns today.. 😉 ) 

If you are reading to start shopping for an outdoor greenhouse be sure to check out my blog post Before You Buy: Questions To Ask When Shopping For The Best Greenhouse by clicking this link here:

If you have any questions or you have had a similar experience, please drop them in the comments.

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