You can grow anything you'd like.... If you know how, and know how to intentionally stress it out the first 3 weeks of veg, it'll stay nice and short, and the stem will become harder, and not so veggie like, but when you put it into flower, start feeding it well, and flush it at around week 2 of flower, and it will begin getting strength again to produce some nice bud... Of course this happened by mistake, but when it did happen, I was like "wow... this is a neat trick for someone with limited space"...
But, seriously.... 20 inches is more than enough to grow yourself almost any plant without stressing it out, as long as it is more than 60% Indica.... Least 50/50..... Tell you what.... I think you should go for a huge producer like the SAGE LST or multiple Single cola clones
How tall is your pot?....
Here are some other tricks...
germinate seed in a rockwool block, or whatever, and place it in a small 8 oz cup of soil or coco..... let it frow for 2 weeks, then transplant it into a 16oz container or so.... I'd say a party cup, but It may be too tall for your room to grow.... So I'd pick something short and squat..... start flowering it, and lst, and do not remove it from this container till you're at about 3rd week of flower(when the stretching period stops)... Then transplant into as big as container possible to allow the roots to expand... The plant will thank you, and reward you with some big fat nugs
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Also so important to veg with 6500k the whole way... Dont mix Spectrums during veg, as it can make your plants stretch, and keep lights as close as possible (1 inch or so, but keep a fan on them and keep temps at 83 at least....... Let your plant grow to like 6 nodes, then top it at the top of the 3rd.....(your choice if you wanna clone that top, which should be more than big enough..... I dont like topping plants soo early on, as they still dont grow themselves enough fan leaves to grow nice and strong... and normally the bottom 2 shoots of the plants are no good anyways.. so i'd take the next 4, and LST them into an X from top view..
Also... If space is an issue.... NEVER cut away any lower foilage or stems... it will just make the plant grow faster and taller... let the plant struggle to try anf grow those bottom stems with that will never amount to anything.... cut all that AFTER the plant stops its stretching phase in flower.... THEN lollipop, and transplant to bigger pot....