Desert/Summer Flowering Room Tutorial

how we planned, built and equipped a flowering room for personal use only.



1. what is NOT covered in this tutorial? If you’re planning a flowering room with more than a single 1000-watt light, this is not the thread for you, because no one can smoke that much personally, we know because we’ve tried and you just can’t do it. You must be selling to at least your mother. this thread does not cover a vegging room that you will need unless you buy clones. Also, this tutorial is not about how to grow. For the basics of growing, check out the first two links in my signature below from authors that have a lot more experience than ours.

2. how much weed/medicine do you want? Start with your current consumption and increase within reason to account for not having to depend on your dealer. My significant other (an infrequent riu member) and I were buying an ounce every other week before we started to grow. We aimed for 3 ounces per month as a minimum. Tip – if you’re smoking more than you want because your tolerance has increased, you can grow several different strains. Rotate what you smoke and your tolerance will decrease. Now that we make our own medicine we use a lot less to greater effect.

3. what kind of weed/medicine do you want? You may not know the answer to this before you have a chance to grow, that’s ok. What’s important for room design is the size of the plant you want to grow. From one site: "The sativa high is often characterized as uplifting and energetic. The effects of a sativa marijuana are mostly cerebral. They give a feeling of optimism and well - being, as well as providing a good measure of pain relief for certain symptoms. They are known to have a quite spacey, or hallucinogenic, effect. Sativas are a good choice for daytime smoking. "


The indica highs are most often described as a pleasant body buzz. Indicas are great for relaxation, stress relief, and for an overall sense of calm and serenity. Marijuana indicas are also very effective for overall body pain relief, and often used in the treatment of insomnia. They are the late - evening choice of many smokers as an all - night sleep aid.


4. how much height do you need? If you are growing a sativa dominant strain and you veg for a reasonable time, your plant will most likely be fairly tall –let’s use 5 feet – after adding room for the container and the light you will need an 8-foot ceiling. If you are growing an indica dominant strain then 3 feet of plant and a six-foot high ceiling is adequate. You can also train your plant to be shorter if you’re caught short, so to speak.
Tip – online seed banks can help with the height of specific strains. and this site has lots of information of training techniques such as length of vegging, sog, scrog, topping, fimming, super cropping, LSTing – the list goes on.

5. how much light will you need? The amount of light during flowering is the most important environmental factor in determining how much weed you can produce. Weed growing is inefficient below 3,000 lumens per square foot for flowering, and excels in light between 7,000 and 10,000 lumens per square foot. There is some debate about amount of light, especially people who use compact fluorescent lights, covered to some degree in this thread. Tip - many people incorrectly use a light’s watts as a measure of how much light they produce, but different lights produce very different lumens per watt, such as a 600-watt hps at 170 lumens per watt vs. a 26-watt cfl at 70 lumens per watt. lumens grow plants, watts are just electricity. we chose to shoot for 9,000 lumens per square foot to try to maximize the efficiency of our grow space.

6. what lights should you choose? we make no commission from recommending any products, we linked to a popular online hyrdo store so you can see the type of products we use but you can get the same things for less in many places, including ebay and craigslist. As for a particular light, we chose a 600-watt hps light for our personal grow. It’s a light that lets you get a good-sized crop even with beginner skills but it’s enough light to grow 21 ounces at a time when you dial in your grow conditions. That ought to take care of you and your closest friends, no? It’s not so big you feel foolish growing only two good-sized plants and you can fit six smaller plants without too much trouble. Your personal usage is probably going to fall somewhere in those ranges. The other benefit of the 600-watt hps light is that it’s the most efficient light made, much more so than a 1000-watt light. Your other light choices are mh, fluorescent and l.e.d., but all are either unproven or much less efficient, requiring higher wattages and greater heat to achieve the same amount of light. The spectrum of light is critical in flowering with 2700k being the standard. hps lights put out plenty of light in the right spectrum.

7. Why don’t you just say how much I’m going to yield? Because the answer is anything from none to 1.5 pounds or more, completely depending on your skills as a gardener, luck and strain.

8. how much floor space?
a. plant space – your choice of light determines how much space you can cover with sufficient light. With our 600-watt hps light putting out 95,000 lumens we can cover 10.5 square feet in a 3 x 3.5 rectangle and maintain our 9,000 lumens per square foot goal. The location we chose also made it easy to have a 7.75 square foot overflow grow area we can cover with cfl’s if we choose to grow more/bigger plants.
b. utility space – you need to be able to move around in your grow space without tripping over your plants. You’re probably also going to want space to keep your supplies in the grow area. Nothing like a big bottle of big bud nutes sitting out on a counter to tip someone off to your hobby, plan accordingly. We have 15 square feet of shelving and walking around space.

9. how many plants do you need? The number of plants depends ultimately on their size, which is to say it depends on strain, training techniques and veg time. Three examples:
a. two sativa dominant plants, such as lemon ice, grown to forty-eight inches tall and trained through topping to be 30 inches in diameter will take up 10 square feet of the growing space.
b. Four indica/sativa plants, such as carmelicious, grown to 30 inches high and 18 inches in diameter in the same space.
c. Nine lowryder plants grown to 12 inches high and 12 inches in diameter.

10. what growing medium should I use? This tutorial does not go into making a choice between hydro and soil. The space and equipment requirements are somewhat similar if you’re doing a soil grow with automated watering capability vs. a hydro grow. Soil is generally easier to deal with and hydro is more efficient.

11. how to choose a good location?
a. Security – until the law becomes rational you need to treat security seriously. Minimum requirements for a secure grow include:
i. locks and/or stealth location – the closet next to your front door is not the ideal place for a grow room. Neither is a utility room that has equipment serviced by outsiders.
ii. odor control – a flowering room smells a lot thus proactive odor control is required. A carbon filter is the best choice, having a jar of Ona Gel on hand for emergencies is good planning.
iii. sound control – if your room sounds like there is a jet engine hidden there then people are going to start speculating. The fans used to cool a room can be quite loud. We use a duct muffler on our exhaust to make the sound less than a dryer vent (we actually used a dryer vent). We also use variable speed fan controllers so we aren’t making more noise than we absolutely must.
iv. light control – you want to make sure light doesn’t get out(for security) and doesn’t get in (for the plant’s required dark times).
v. not to worry – about helicopters, infrared, electricity usage or the like. There is no practical difference any technology can expose between a personal grow and an endless number of legal hobbies and the toys they use. Do worry about smell and ex’s of every kind, don’t waste your time worrying about the spy stuff. But if you’re using multiple 1000-watt lights, you’re on your own.

b. Electricity access – indoor growing takes a lot of juice. If you have an excellent location except for electricity then look into having an electrician add the necessary lines before your grow space looks like what it really is. Add up the amperage of all of your equipment (listed later) and make sure you can get that much electricity to your room plus a safety margin. It would not be unusual to need 30 to 40 amps. Caution is suggested for d-i-y electrical projects because poor workmanship can result in fire hazards. If you’re curious, calculate electricity costs by appliance watts x hours used per day divided by 1,000 and multiplied by your price per kilowatt hour. our co-op charges 8.2 cents per kwh for example.

c. Water access – it is a real pain to carry buckets of water around the house because of a dry grow space, and there are few good choices to make an unattended grow space without access to water (so you can go on vacation for a week and not worry about your plants). If you’ve chosen to grow hydroponically, then you must have water access. Same as for electricity, if you can route water to the grow space before it’s obviously a grow space your life will be much easier going forward.


d. Temperature control – your biggest challenge, especially in the summer, is to cool your grow space. Ideally, you have central a/c and can find a grow location where you can tap into it. Unfortunately for us, our space is outside the home’s central a/c and summer temps are often above 100 f (a cool 98 f today). Our space also has a south-facing wall. Details on how we handled it in cooling/ventilation later.

12. if and how much CO2? CO2 is another important environmental factor for your plants. They need at least the concentrations of CO2 found outdoors (250 – 350 ppm) and can benefit from enhanced levels of CO2 (1,200 to 1,500 ppm) only if the other environmental factors are optimized also. Most indoor personal grows will have enough CO2 migrating into the grow space without having to take any actions at all. Just looking in on your grow once or twice a day is sufficient. However, enhanced CO2 will help your plants grow faster and bigger, so it’s another way to make the most efficient use of space. In our case, we added a propane CO2 generator and a CO2 monitor/controller, we just had to give ourselves an extra challenge for cooling.

13. how to plan your ventilation system? Weed likes temperatures between 65 f and 75 f without CO2 and up to 85 f with CO2. The basic decisions on how you construct your ventilation system are determined by whether or not you need to cool the air and whether or not you’re using enhanced CO2. If the answer to those two questions is yes, then you want to minimize the exchange of air with the outside. If the answer is no to cooling and enhancement, you are going to need a lot of air exchange in your system. In our case we’re experiencing a typical 100 f summer so cooling is absolutely required, and as said we’re adding CO2.
a. How much cooling - this calculator is excellent for sizing an a/c. but it gives the theoretical cooling that can be impossible to reach unless you carefully plan the design of your system. Can’t go wrong by doubling what the calculator tells you.

b. What kind of cooling - These are your choices, in order of highest to lowest cooling capability:
i. Tie into your home central a/c. by far the best choice if you can do it.
ii. Add a split mini a/c system. These systems are almost as effective as a central a/c but are sized for single rooms. Downside is price and professional installation or charging required. We have a splt mini in our veg room and have never had a temperature problem.
iii. Add a dual hose portable a/c. these can be almost as effective as a central a/c if you take special precautions to handle the heat they generate.
iv. Add a single hose portable a/c. we recommend against single hose systems because of poor efficiency and the fact that they exhaust room air without being treated for smell.
v. Add a swamp cooler. We recommend against this option because of relatively little cooling achieved and added moisture that’s not wanted during flowering.

c. What kind of room exhaust hole is needed - in our case, exhaust of room air is limited to occasional use to remove trapped hot, stale air every couple of hours. A four-inch vent hole to the outdoors is sufficient for this limited use. If you are building a room without cooling, plan on as large as an 8-inch exhaust hole. Make your final choice of hole size based on the fan size you choose later in the process.

d. What kind of air input is needed - The smallest grow spaces can get enough incoming air from leaks around the room. But most grow spaces will benefit from one input hole, even without a fan. Ideally, you want your exhaust fan to create a slight vacuum so that there is no chance of smells leaking out of the room, so plan your input with or without a fan to create less airflow than your exhaust.


e. Treating your air with carbon filter - you will want a carbon filter on the inside of your grow room directly connected to a fan. That fan can be simply recirculating air in the room if you’re using a/c and/or CO2, or ducted out the exhaust if you’re not cooling/enhancing. There is a lot of debate about the placement of the carbon filter and fan, here’s our take: security is the most important factor and you will be assured of treating the most air with this recommended placement. If you move the fan away from the filter, then untreated air can get pulled into the ventilation line through any leaks. If you move the filter outside the grow area and blow air through it then all of the air in your room will still smell. This is not the most efficient use of the fans but we trade security for a little efficiency.

f. Cooling your light - The light itself usually produces the most heat of anything in your room, not including the a/c exhaust. Adding an air-cooled hood and dedicated ventilation line can help this. The other benefit of an air-cooled hood is that you can keep your light closer to the plants, enhancing growth and yield. You need an entry hole and exit hole for the light’s ventilation, either 4-inch, 6-inch or 8-inch depending on the hood. If you are not cooling/CO2 enhancing then many people combine the carbon filter line with the light cooling ventilation line as follows: carbon filter->fan->ducting->light->ducting->duct muffler->exhaust.


g. Sizing your fans - you will not know how much air movement you really need until you’ve built your system and turn it on. A practical way to handle this is to get a relatively large capacity industrial inline fan and a separate variable speed controller. a fan that’s running faster than you need is going to be louder than you want and a fan that’s running slower than you need is going to be worthless. The guidelines for fan size are very broad (from one room air exchange every five minutes for fresh air up to 2 or more exchanges of room air per minute to handle high temperatures). As an example, our flowering space is 270 cubic feet so could require a fan of 540 cfm or greater if we were using it to bring cool air into the room. We settled for a 440 cfm fan on our carbon filter line with a 170 cfm fan on our light cooling line, both with variable speed controllers. We probably could use a stronger fan on the light cooling line judging by the high temperature of the air leaving the light.

h. Adding recirculating fans – you want to provide good airflow inside your grow space to even out temperatures, remove waste gasses from your plants and strengthen the plant via air movement. We have one oscillating fan and one still fan in the room in addition to the carbon filter’s fan that recirculates air most of the time and the a/c blower. Tip – when I thought I had everything dialed in I noticed a very obvious vibration with my hand on the outside wall of the growing room. I searched all my over-sized industrial equipment but it turned out to be the little oscillating fan causing the problem.


i. Ducting – it is very important to use insulated ducting on all lines that are carrying relatively hot air or you may not be able to cool the space at all. This is especially true for the a/c exhaust line. Also, plan all ducting lines as short as possible consistent with few kinks or corners.

14. Step-by-step on how we prepared our space?

a. Choose our space – we have a vegging room but no place left for a flowering room. Our best option was a storage shed that is attached on one side to the house, on another side to the garage, and as said has an exposed south-facing wall.



b. Buy a tent or build walls (d-i-y walls) to create a defined growing space if your area is considerably larger than the space you need to grow. It is better not to grow in a small part of a larger space because then you have to create an ideal grow environment in a larger area which will cost more and be harder to maintain and possibly to secure. In our case we split the shed with a new wall and a hidden door.

c. map out your grow space – we planned for up to six plants, each 18” in diameter based on our plans in paragraph 5 above:




d. Cut holes in walls for ventilation – you can’t make scrambled eggs without breaking a couple of eggs. Remember, any hole you make can be fixed if not needed later, and trying to build a grow room without holes is just going to lead to frustration. You want exhaust holes generally at the top of the room and input holes generally at the bottom, to take advantage of temperature differences at different heights.




e. Provide electricity access – in our case the room had enough electricity for everything except a portable a/c. we laid a heavy-duty extension cord from the garage to the shed instead of relying on an electrician.

f. Provide water access – we laid garden hose from the garage to the shed, again to avoid a plumber. We can also tap into an existing reverse osmosis system as a future upgrade.


g. Install your lighting system with adjustable light hangers, ducting and fan. Don’t install the actual bulb or the glass enclosure until you’ve finished the rest of the room to protect against breakage. Use insulated ducting for air that’s already passed through the light. Seal all of your ventilation joints with pipe clamps, screws and duct tape or you could have a fatal-to-your-plants heat leak in the middle of the night:

h. Install your portable a/c. as you can see from the diagram, we first tried the a/c in the southeast corner of the room. But no matter how well we insulated the exhaust it still heated up the room too much. We settled for it’s final position which is not very convenient for getting around but allows for a very short insulated exhaust line that dumps into the house a/c return line. We also made the portable a/c super efficient by feeding it 75 f air from inside the house to cool its compressor.




i. Install your carbon filter. Place at the ceiling to help draw out hot air when exhausting. In our case, we added a y-joint with one direction recirculating air and the other direction venting to the garage. Each arm of the y has a damper, one with a normally open controller and one with a normally closed controller. the system is tied into the thermostat and changes from recirculating to exhausting if the temps get too high. The air can also be re-directed remotely over the internet using the controllers described later





j. Install CO2. We squeezed the CO2 generator into a corner of the primary grow area, suspended about four feet off the floor. CO2 is heavier than air and the fans in the room distribute the flowing gas evenly.






k. Install watering system, waiting on parts. We want to be able to leave our grow unattended for up to 10 days, so we required a pretty foolproof watering system. Simple is best when you absolutely have to depend on something so we combined a submersible pump and a household drip irrigation system to provide water on a day of the week basis. We fill the reservoir with a water level-sensing shutoff valve and use the submersible pump to push water to the plants on a predetermined schedule.




l. Finishing touches – add mylar to your walls to increase the efficiency of your lights and cover the floor with a waterproof tarp to protect against leaks. Organize your electrical lines with all connections above potential spill levels. Label everything.

15. how to control your system? We want to be able to check up on our grow and make key changes when away from home. There are many automation options, we chose an inexpensive and simple x-10 scheme to have automatic day of week actions as well as on-demand remote actions. Because these systems are not foolproof we use mechanical timers as our primary control and have automated remote overrides of the light, a/c, CO2, venting out and eventually watering.





16. how much will it all cost? here are approximate retail prices of all of the major equipment purchased for this grow room. You can get better deals if you avoid the hydro stores.

1. Ventilation and odor control:
Carbon filter $250
440 cfm fan $200
170 cfm fan $175
2 variable speed fan controllers $150
various ducting products including insulated duct,
y joint, back draft preventer, reducers, duct muffler $250

1 two hose portable a/c $600
1 co2 generator $450

2. Lighting system:
Ballast $250
Air cooled hood/receptacle $200
Premium hps bulb $100
Timers,power strips, extension cords $100
Power cycle protector $75
Thermostat protector $25
cfl's and gear $200

3. Control system
Automation controller $150
Co2 monitor/controller $400
Thermostat $175
2 low voltage contact closures $100
2 120 volt controllers $100
water control meter $75

4. Water control system
submersible pump $300
drip system $100
RO system - optional

totals $4,325



17. Test your room or lose some plants. Finally, nothing tells you your room is ready for plants like 48 hours of operation without a glitch. We have lost plants moving them into an unstable room and you will too unless you take the extra time to let everything settle down.

Very happy growing!!

here's the room with its first tenants

Brilliant stuff desertrat. I can only dream of growing room of that class in the future. I particularly liked the hidden door! Very well disguised. Have you been growing any Sativas in there?

Thanks. Put my first two sativas in this week. Funny thing is they were plants my nephew was growing in his bedroom at our house - a big no-no if you're hiding a grow - and he had no idea the room existed. He couldn't even find it when I told him where it was. Great fun.

Wow I cant believe this thread doesnt have more replies! Great thread desert, +rep for you.

Great Thread! Im saving this one for sure

Awesome thread, thank you

Great thread man + rep no doubt

Great tread learned a lot

+rep, luvu!