How many chickens for my space??

[rosemarythyme]

I'd probably do 4 in that space, assuming the 20 sq ft is all open floor space (not feeders, waterers, nest box). You can "add" a little extra space by cutting out a nest box, if that's not already built and installed (if it is, don't sweat it). With 4 chickens it'd be nice to have an extra box, just in case you get a broody or a lounger.

A bigger run is definitely needed if you can't free range daily. Even if you do plan on free ranging it's a good idea to have a run that meets or exceeds minimum size recommendation of 10 sq ft per bird, as there might be times the chickens need to be locked up (a predator around, you're on vacation and want that extra security, etc).

 

[aart]

I was thinking of letting them free range in there less supervised assuming none of my trees or plants will bother them.

More likely they will bother the plants, they can scratch up the roots and eat the foliage.

You're gonna need massive deep shade in your climate...and lots of ventilation in your coop during summer....plus for a desert environment is that misters will work well to help cool them off.

 

[lazy gardener]

Your space as described is big enough for 2 birds. If you have already bought it, which I assume is a prefab, take it back, if that is an option. All pre fabs are poorly constructed, poorly designed, lack adequate ventilation, usually do not have enough height in the coop section to allow ventilation to work properly without increasing risk of frost bite to birds. Nor do they have enough height in either coop or run sections to allow good waste management or enough litter.

A good coop: has open floor space at least = to 4 s.f./bird, Ventilation is 1 s.f. or = to 10% of floor space, which ever is greater). Ventilation is at multi levels, and placed so there is no draft on bird when she perches. Has natural lighting. Provides 1 l.f. of perch per bird, with perches being at least 15" from back wall and 18" from ceiling and floor, and having enough room for birds to spread their wings full length and fly down from perch without smacking her face on the wall in front of her. All openings are covered with WELDED 1/2" hdw. cloth. Is preferably walk in style so you can manage coop and birds easily.

A good run provides at least 10 s.f./bird, is walk in style so you can manage deep litter in the run. Is roomy enough that you can provide multi level stress busters. Otherwise, you need to be planning to go in and rake out the poop on a regular basis. Deep litter will help keep flies, stink, pathogens in check. A well managed deep litter run never smells bad, never needs to be cleaned.

Crowded chickens are prone to stress induced illness, as well as behavioral problems: feather picking, aggression including blood shed and leading up to cannibalism.

 

[cmom]

More likely they will bother the plants, they can scratch up the roots and eat the foliage.

You're gonna need massive deep shade in your climate...and lots of ventilation in your coop during summer....plus for a desert environment is that misters will work well to help cool them off.

All of my pens have shade trees and shade/rain tables for the birds to get under.
I don't have misters but do have sprinklers in some of the pens but all of the pens get the benefit from the sprinklers.

 

[Mimi13]

Yes, I agree with @lazy gardener. I was one of the poor souls who was duped into thinking the little prefab coops were the way to go...not! I got six birds (the manufacturer said I could put up to six) and quickly had to do some reconstructing of the coop. First off, the three nest boxes were waaay too small, so I made them into just two. Then I had to increase ventilation, add windows and raise the roosts. As it turned out, two of my “hens” were roos and the breeder took them back, thankfully. So I ended up with four docile hens who made it just fine for a little over a year in the little coop. Luckily, I had a very large and very secure run so I didn’t have to close the coop door. And because I didn’t lock them up I noticed one night that the least dominant hen started roosting on top of the coop, right up under the covered run roof. I had set my little coop up on top of another enclosure that I built to put their food and water there, so the top of the coop was about six feet high. She has done fine up there and another hen has joined her in the past month. Inside the little coop just couldn’t contain the different levels of pecking order in such a close space, I guess.
I have almost finished building another coop and run. Right now it is home to my 24 six week old chicks. Once I have integrated them with my four older hens they will all reside in the new coop.
I am thankful that my initial small coop didn’t cause severe problems within my little first flock, and it probably would have if I hadn’t had the secure run that the birds could roost in.
I wish you the best with your new chicken venture. It is very rewarding.

ETA: I thought I would add a picture of my little coop set up.