Grow Guideline

Good Day All!

I’ve read some issues folks have had and figured I’d done lots of research on these topics over the years including, but not limited to this community. Figured I’d share in the hopes it helps some of the new growers. I’m new to grobo, but not new to growing. This is not grobo approved, just my own grow guideline. Most important is to listen to your plants. As this is a guideline to use as reference you should be changing it based on your specific conditions, locations, seed genetics ect.

Utilizing a sample recipe from Grobo

Sample recipe
Germination (10 days)
Early veg (14 days)
Veg (14 days)
Stretch/transition - marks the beginning of flower (14 days)
Full flower (37 days)
Flush (10 days)
Dry (2-5 days)
Cure (2-3 weeks but 4-8 weeks for optimal ranges)

Seedling Stage

(Germination - 10 days)

  • Seedlings and clones like high humidity levels of 65-70%
  • Reason: The root system is not established
  • High humidity levels allow water intake through leaves
  • Temperatures with lights on: 68-77 degrees (lights off: 4-5 C° lower)

Vegetation Period

(Early and Reg Veg (28 days)) - by this time you should have topped your feminized photo - 5 nodes - important continue these into the next phase. Remember you’re hurting your plant by cutting it, give it a few days to recover.

  • Humidity levels can be lowered by 5% each week (acceptable range: 40-70% - ideally 65-70%)
  • Temperatures can be increased a little bit (no obligation - no higher than 82 if possible)
  • Reason: Roots absorb more water; evaporation through leaves cools plant(s)
  • Temperatures with lights on: 71-82 (lights off: 4-5 C° lower)

Flowering Period

(Stretch then Full flower (51 days)) crop, top, lollipop and LST is advised - make sure to never remove more than 1/3rd of your plant when cropping. This would be an ideal time to remove fan leaves that are blocking light to Bud sites. By now you should have no less than 8 Bud sites due to your topping. You’ll want to clean your plant up during this stage. Remove useless material on the bottom 3rd of the plant. We want to make sure the energy is focused on the Bud sites not leaves at the bottom.

  • Humidity levels need to be lowered to 35-50% (important)
  • You can get away with 55% (anything over 60% is typically real bad)
  • It’s best to slightly lower temperatures in flowering
  • Temperatures with lights on: 68-78.8 (avoid high temperatures)

Late flowering

(1-2 weeks before harvest - flush - remove everything, no more nutes, only add RO/Distilled Water mixed. I use Flawless Finish, but that’s a personal preference as an add-in.

  • The following steps are not necessity, but can improve yield, flavour and appearance
  • Bring down humidity levels as much as you can: 30-40% - target 30
  • Lower daytime temperatures, and also increase the temperature difference (day/night)
  • Temperatures with lights on: 64-75 (lights off: minus 5-10 C°)

Invest in your grow! Basic Tools you need to optimize your chances of a successful grow

EC, TDS & PPM meter ($15)
Ph meter ($62 temp and PH - they can be had cheaper)
Hydrometer (temps and humidity - $20)
Scissors (for a set for $20 designed for plants)
ScrOG/Trellis - making my own in addition to LST (free)
Jewelers ring ($10)
Medical gloves (free for me)

Add a fan to push more air. This can be internal or external pointing at the fan intakes

Fans inside or outside pointing at the grobo fan intakes or turn up the AC
An alternative would be to safely remove extra growth from your “heathy” plant

humidifier - small portable ones can be added to the grobo, but likely never will need to be due to space constraints

Hope this helps some folks. If anyone wants to add or edit it feel free to do so or if the grobo team has issues I can edit or delete.

I’m online all the time so if you’re not comfortable posting in the forum and want help you can send me a DM. Lots of very knowledgeable users in this community; take advantage of their willingness to help!

Happy Growing!

40 days after start
Time for Topping, slow apikal growth on Day 31 (7 late veg)?
Hello! Patiently wait on my grobo!🥴 [UPDATE!}
HulkBerry, firstgrow
Wedding Glue - Day 30 - Too short?
Yellow Spots on Leaf tip
First grow: white widow from canuk seeds
New on here
Knowing when to end germination stage
New to growing
No tap root after 5 days
First grow: White Widow
White Widow - First Grow
Should I add more time to late veg?
New here First Grow (Gummy Buns)
Fim, top, etc
Ambient house temps related to growing
Noob, something looks off [RESOLVED]
1st time grower
Inside LED
Northern light fem
Germination Day 4
First grow: Blue Widow
Blueberry Muffin - First Grow
Just made the purchase of the Premium!
Baby Skywalker
First Grow GDP! (Late Vegetation)
New grower-tips, advice and guidance needed!
Germination great white shark
Are these spots ok and the bottom fan leaves? Day 8/14 early veg
Leaves with Orange tips in Vegetation Stage
New skywalker grow
First grow Girl Scout
2nd grow early veg 3/14
Interested to make a plant grow
California Dream Fem (1st grow ever)
Day 23, my first grow with a Grobo
Water temps/grobo temps/humidity
First time doing this
Grow Recipe_LSD
Tangerine Dream
Early trim
Needing some advice
Blue Dream Scheduling Mishap
First Grow - Kush Cookies (Barney’s Farm)
1st grobo trial grandaddy purp! Day 34
[First Grow Ever] Banana Daddy RBX1 by Ethos genetics
New grower!
New member, introduction and request for some general advice
JoGro _Grows
First Grow - CBD Blue Shark
Water temp and humidity
Brand new to this! 1st!
Long time coming!
What can I do
Pests problem?
Sour Diesel

Great post. If I may add stay away from the cheap pH pens that cost $20 to $25 I know you posted higher priced ones but that can’t be stressed enough not to cheap out on the pH meter.



Agreed! As an amazon prime customer I bought 3 to test the validity of the ranges and ph 4,7,10 for testing purposes. The cheaper devices seemed to be off by considerable margins. Enough to make me question the results. They were returned (free). Ultimately kept the device that cost 3 times as much as the others, but was much easier to use , tested temps and was spot on


Wow, nice work @James!!




Grow Guideline





This is excellent information!!!
And you’ve even aligned it with the schedule that Grobo uses! Thank you!!

Question… Thoughts on my topic?


@omacoder Thanks! I want all growers to have bountiful harvests. If that info helps one user then it served its purpose. I have a lot more data relative to the grobo, but never posted it cause I only had the unit less than 30 days before moving into tents. I may spend some time compiling that data in a PowerPoint to share with the group at some point, but with a harvest In the next week or two and the holidays this is not a priority.

As for sensors… I ended up buying a dozen units off amazon ranging in price and features. These were all tested in a very controlled environment/server room environment with industrial a/c, many industrial sensors, sensaphone equipment, UPS/Backup gens, ect ect. What I found as a vast majority of the devices were off and some were significantly off of true temps and humidity. I ended up with this Govee WiFi temp which was within 1 degree of true temp and humidity and easily the closest to accurate readings of the units I purchased. It also has a remote readings feature as I was able to monitor my tents while at Disney (several states away) or anytime away from home-base. It sends push notifications when temps or humidity exceed your notification settings or you can check manually at anytime. Pretty happy with the device and the features including exporting all the data to a .csv file for ease of access. Most important is it’s rechargeable battery operated and still has more than 50% battery life after roughly 3 months of 24/7 use and more accurate than all the others I purchased. I would recommend this unit as an inexpensive accurate rH/temp thermometer.

I ended up with 3 of these (overkill) and most of the others were sent back. What I’ve found, in my flower tent is the floor where the cool air is coming into the tent is usually around 70 degrees with lights on. At the top of the colas or 12 inches below the light is 75-78 degrees and above the light where my ac infinity exhaust fan is the temp is between 75-80 degrees. A 6-foot difference from floor to ceiling and a fairly wide range of temps and humidity throughout (10 degrees/rH). I rigged up these sensors at different heights to get better readings throughout.

It doesn’t surprise me to see you have different readings throughout the grobo due to the fans. Humidity and temps will fluctuate for many reasons even a few inches away based on air flow, the plant in the middle restricting air flow or forcing into a different pocket ect. Most tent setups have an oscillating fan forcing those pockets to move continuously. The grobo has the fans mounted and are high powered pc fans (essentially) with a direct air flow. The spread of these fans is affected when an obstruction is in place (your plant). Since each plant you grow is different you should find that each grow will produce different readings no matter what you do. I wouldn’t over think the grobo. They designed it so you didn’t have to. If you really need to get to the bottom of it, I would free hang two sensors on each side near the top of the plant. Take the two data points and find your average. You’ll still have pockets within the unit that get more or less air flow, but the space is small and shouldn’t be a concern.

Hope this helps


Just wanna add, do not put a humidifier inside the Grobo… I knew I read this post before and have seen others do it on the forums.

@Stephen has confirmed this recently with a warning. It can damage or kill your Grobo.


Thank you :+1:t2::sunglasses: