1. Freeze it. Information from the National Center for Home Food Preservation:

Cauliflower

Preparation: Choose compact white heads. Trim off leaves and cut head into pieces about 1 inch across. If necessary to remove insects, soak for 30 minutes in solution of salt and water (4 teaspoons salt per gallon water). Drain.

Water blanch for 3 minutes in water containing 4 teaspoons salt per gallon water.

Cool promptly, drain and package, leaving no headspace. Seal and freeze.

2. Make different dishes with it and freeze them in user-friendly amounts.
- pan fried
- as a rice substitute
- as a mashed potato substitute
- lots of low-carb and paleo recipes using cauliflower

3. It keeps longer in a plastic bag, and some suggest a paper bag. It should keep bout 10-days whole and if it has already been prepped into florets should be kept for no longer than 3 or 4 days (so freeze any leftovers). You should eat cooked cauliflower within 2 to 3 days, otherwise it may start to smell sulfur-y.

4. DON'T vacuum-seal it for refrigerator storage ["Cruciferous vegetables (broccoli, Brussels sprouts, cabbage, cauliflower, kale, turnips) emit gases during storage".]

-Grainlady

Grainlady - what is meant by water blanching? Does it mean to soak it in boiling water with the salt and then cool it down? Sorry to be so ignorant but want to do it right. I like to use it in salads but guess it just doesn't keep that long? Barb

And you can always trim the black spots off the head too.

Boil it for one minute, drain and put it under the cold tap to cool it down quickly then freeze in portion sizes.

Barb-

Blanching: complete information about blanching and the different methods and times for different vegetables can be found at the link below. Be sure to count the blanching time from when the water comes back to a boil - AFTER you add the cauliflower. BTW - one minute is NOT long enough to inactivate the enzymes for cauliflower - as suggested by islay corbel.

An alternative.... When you want some fresh cauliflower, get it at the salad bar at your local grocery store. That way you will only need to purchase what you need for a few days rather than purchasing a whole head. I often use the salad bar when I need a small amount of something when fresh produce is expensive in the winter (need 2 T. chopped red bell pepper, 1/2 c. of fresh broccoli, etc.), or if I want special toppings for a veggie pizza without having to fill the crisper drawer.

-Grainlady

Here is a link that might be useful: NCFHFP - Freezing / Blanching

I know you said you like to eat it raw in salad, but have you tried roasted cauliflower? I like that as a snack or also tossed over a salad. You could buy a whole head, and roast half. The roasted cauliflower will keep in the fridge a week or so.
This could increase your options.

I know this, cauliflower is mostly absent from my life even though I love it, for this very reason. I chow down on it whenever I see it on the crudite tray at a party! I wish they would sell smaller heads at the grocery store. I guess it's not worth a farmer's time to grow less mass of something . . .

I buy it frozen sometimes. Very handy to have when you don't want a lot.

I'm with pcramer on the black spots. As long as not serious, always thought that was what a veggie peeler was for.

Not a fan of overly convenient food, but this might be a time to hit your supermarket salad bar? If looking for 1-2 servings, and stuff at salad bar looks nice and fresh, I'd probably grab a few handfuls (NOT literally grab) there, even though lb/lb a whole head would be cheaper!?!

I have the same problem with just the two of us at home now. My son gave me a pair of Blue Apples from Bed, Bath & Beyond. They go in the produce drawer, and they keep produce fresh for a long time. (I'm not yet sure how long since I haven't had to throw anything out since I got the apples!)