Plant Spacing and Tray Lids in a Homemade Hydroponic System

by Jason

I'm planning two 4x4 (7' tall) tents both with 3x3 trays for DWC. What I'm thinking is the first tent will have a mother, room for cloning, and the rest (more than half) for veg. The second tent will be for flowering. I'm trying to plan for max yield in that space, and thinking of just 9 plants (getting to 4' tall) in the 3x3 flower tent.

But, I've seen 3x3 lids that have 24 holes. Nine and 24 is a big disparity. So which is best? Also, should I do 3", 3.75" or 5" net pots? The pot size won't change the root/grow potential, right, just the stability of the plant as it gets bigger? I can plan the veg spacing backwards after I finalize what will go in the flower tent. So basically my question is, how many plants for a 3x3 tray and what size net pots? Thanks in advance.

Also, though I am trying to build my own cheaply, such as looking at Walmart storage bins. I found buying a sturdy 3x3 tray from Botanicare was well worth the $90. The lids, however, are another matter. Not only are they not that easy to come by, but I feel like I can make my own much cheaper ... if only I could find the right material.

I would like to find two 20x40 pieces of hard plastic (I figure it would be easier logistically not to have one huge lid) and drill holes myself. Unfortunately, I haven't been able to find anything to satisfy that need. I can't use plywood, for example. Any advice is much appreciated. Thanks again in advance.

By the way, and I'm not a typical compliment gusher, but your site is probably the most informative one I've found, which I'm glad I did. So thank you.


Let me tackle the flowering area first. If your flowering area is lit with a light that is intense enough, say a 600w or 1000w high pressure sodium light, then you should have 18" of effective light penetration into the plant canopy (or 24" at the most). This means if you grow your plants any taller than 24" before flowering them, you should probably keep the top 24" intact, but strip all the branches and leaves below this point to the main stem (all the way to the soil or grow media).

The lower branches get first dibs. As nutrients are taken up these lower branches will feed, but they do not receive enough intense light to produce any bud density....only larf and lightweight toasters that are a pain in the ass to trim! You want these branches and leaves removed, and the time to do it is in the first two weeks of flowering! Plants take about 2 weeks to transition or adapt to anything. Once you are 14 days into flowering, your plants will be putting on flower weight almost exclusively. Any pinching, cutting, or pruning you do after this point will lower your yield! All your topping and training should be done by this point! Don't do it!

9 plants in a 3'x 3' tray. That's 9 square feet, or one square foot of plant canopy per plant. Most cannabis plants will double in size over the course of flowering. Putting freshly rooted clones in at 7" or 8" tall would yield finished plants 14" to 18" tall, with each one desperately trying to occupy more canopy space than the square foot given to it.

You will have to experiment a little to get things just right in your garden. Every garden is a little different, and all plants and genetics are a little different. Putting clones into your flowering room a little larger may cause problems with over-crowding in the plant canopy. Or you may find it suits the garden space very well and increases your yield. Either way, the "sweet spot" for maximizing the yield in your garden space will be to put plants into the flowering room when they are between 8" and 12" tall.

Clones that happen to be 8" tall and just popped fresh roots may produce a little less. If you snatch them up as soon as they pop roots and immediately transplant them into bigger media, they may have extra time to develop roots before they are flowered, and will likely yield a little more when they are finished.

Plants going into flowering at 7" or 8" and finishing at 14" will have about 3/4 oz of flower on them. This is a very rough guide, as there are MANY variables at play.

The size of the netted pots makes little difference. It may be easier to find the 3" netted pots at your local hydroponic store. If you end up going with a giant lid, nine 3" holes would affect the structural integrity less than putting nine 5" holes into the same lid. You won't be growing your plants big enough to require a 5" netted pot anyway!

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Unfortunately, I have been gardening for over 24 years and I have only just recently mastered this difficult skill....and even then, only because I happened to find a very easy to follow, high quality technique and decided to follow the instructions to the letter. I produced more high quality compost in just one week than I was able to use in a whole year! If you can master the technique, I highly recommend it. It is one of the top 3 things you can do to increase the productivity of your food production efforts, while at the same time decreasing the amount of effort required to grow all of your own food, and decreasing the total cost of operating your food production system.

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