First Welcome Chris.
Second: It's probably too late in the year to breed kingsnakes.
Third: IF your female is large enough in the spring you might consider breeding her.
Fourth: If you breed them too young, the female will most likely become eggbound which can result in her death or hefty vet bills.
Fifth: As far as a decent size to breed a cal king, I bred my female at 18 months of age, she was around 40 inches and had very good weight. (I don't have a scale, so I don't know how many grams she was) I'd guess she's about 24 oz to 32 oz right now, and she's regained all of her pre-breeding weight.
sixth: Her eggs were 2 inches long and at least an inch in diameter. Keep that in mind when you think your snake is large enough to breed.
Seven: On kingsnake.com home page at the top is a link to FAQ/Care sheets. You'll find a link to a paper on breeding colubrid snakes. Read it now. Read it this fall when you get ready to brumate your snakes, read it in the spring when you get ready to bring your snakes OUT of brumation, and again before you breed, before she lays, before the eggs hatch, and after the eggs hatch. That's what I did. It's a bit of time to wait, but it's worth it!
>>hi my name is chris and i am 13. i have a 9 month old female cal king. yesterday at the reptile show i bought a male cal king about the same age as my female but it was alot bigger. i guess the breeder was power feeding it, unlike how i feed my female. if i start feeding more will she start to beef up before this november or will she just get fat. i want them both to breed this year but i dont think my female is ready. i heard that if you breed them to young it can mess up the female real bad. dont they have to be at least 200grams (7oz) to breed? also it would be a great help to me if you could give me some tips on breeding cal kings, i know pretty much already but i want to know it all so i make no mistakes on my first time ever breeding reptiles. thanx for the help, chris
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~Sasheena