When it comes to yeast ranching, I'm usually a mason-jar kind of guy. I scoop up a big helping of slurry and store it in the back of the fridge until I'm ready to reuse that strain – normally not waiting too long so that the yeast stays healthy, fresh and viable.
That's one method for saving yeast at home. Another one is using slants. These are relatively small volumes of yeast grown and kept inside test tubes filled partly with malt agar. (The name derives from the technique of allowing the agar to firm up while the tube rests on an angle, thus maximizing the surface area available for the yeast colony to grow on.)
There are advantages to using slants, including the ability to store the yeast for a very long time (some say indefinitely) and the ability to keep a clean, pure strain on hand to grow from as desired.
I was eager to try my hand at growing yeast from a slant – not creating my own, mind you; that may come down the road – and I was also eager to get my hands on Wyeast 1028, a strain I'd not yet worked with. Enter a friend in my homebrew club, a dedicated slant-keeper and yeast horder, who offered to give me a fresh slant of Wyeast 1028 from his stash after I'd mentioned my interest in it.
When it was time to start growing up a starter of the yeast, I took my slant out of the fridge, made 20 mL of a 1.040 wort with DME, fashioned a loop from a paper clip, sterilized it with a flame, and simply scraped some yeast off the slant and inoculated the wort (a volume so small I was able to start it off in a used White Labs yeast vial).
Following my friend's instructions, I stepped the volume up to 200 mL about 24 hours later, and then up to around 1.2 L another day after that. And with that I had a starter ample enough for the British Bitter I'll be brewing tomorrow.
The exercise has been moderately labor-demanding – there are worse things than doing a small homebrew task every night for a few nights, but plan accordingly – but not anywhere near as intimidating or unreasonable as one might think when first considering entering into the world of slants. Things have gone so well, in fact, that I might even consider setting up a yeast ranch of my own, monopolizing every vegetable and cheese drawer in the process but ensuring an ever-growing and ever-ready stable of strains to suit whatever my brewing fancy demands.