I don't even boil them. I just throw the mason jar or swing-top bottle into some iodophor at the end of the boil and then fill it up, label it and toss it in the fridge. The cold in the fridge keeps it safe from any wild bacteria, and it will keep for more than a month. It also helps when I forget to take a hydrometer reading... And I actually quit taking the time to do all that, now I use a couple grams of sugar per ounce of water to start my yeast. I have heard that when priming, you only want to give your yeasts around 1.030 gravity. The reason for this is when you pitch the yeast, there is a change in environment. If you prime with 1.060 wort, you put the yeast in an environment with 6 or 7 percent alcohol and when you pitch into your wort, there is almost no alcohol, this can shock the yeast some, and it may take longer to achieve and active ferment witch can lead to off flavors. yadda yadda. Also, I think the yeast can mutate eventually when it is subjected to high alcohol levels. If you are hell bent on using 100% hops, water, and grains; when it came time to prime the yeasts, I would just dilute the wort to close to 1.030 and boil for a minute, chill and prime! And if by wort starters, you mean primed yeast, then you should already have it in a sanitized container, then just throw it in the fridge and you are good. Or sanitize a mason jar w/ iodophor and transfer. Sorry for being long winded. Just trying to be thorough and concise.
Good luck and have fun!