Did you buy a tiller just for 6x25 feet or do you anticipate having a lot more space? If it were me, now into the CA dry season, with hard, dried out soil, I would buy a bunch of good-quality straw and spread that very thick on the ground having first spread some well-composted manure, and then keep it good and moist until the rains come. Let that ground loosen up on its own, and maybe plant some cool-weather crops in late September.

I'm hoping to get prepped for cool weather crops as I pull out the Spring stuff, but I'm not sure when to plant them so I'll be watch this to see what others tell you. I do agree you'll need to do a lot of prep. Maybe start with a small area for cool weather, and then work on the rest over the Fall? Of course it's not going to rain between now and October, so hopefully somebody can tell you how to prep the land properly without rain.

Good luck! This is my first year being able to grow in a real garden so it's all an experiement.

UC Davis has some good info, and our area has a UC Master Gardeners website associated with Davis that's really helpful for timing.

Some suggestions for your adventure:

Take what fits & leave the rest. Marianne Binetti one of my favorite garden writers says you have permission to ignore any gardening advice given. Well said. There are many ways to garden and mostly preferences. :o)

1. source local materials & information

Go to the regional gardening forum for California here on GW to locate sources of farm manure and/or straw bales directly from a farmer for the best prices and volume. If you want to purchase retail go to a farm animal feed store not a hardware store for the straw. You could compare prices on bagged manures if you have to go that route. Most bagged manures aren't very potent and you want all the good stuff.

It doesn't matter what type of manure as any of it will work as the bottom layer as suggested covered with straw. I've used horse manure in recent years to increase organic matter content of glatial till. Previous to that backyard chicken, duck, and rabbit manures. Quantity made a bigger difference than quality for our garden. Sure rabbit and chicken manures are potent, but we didn't have pickup loads of it like the horse manure with sawdust as bedding.

I would suggest a minimum of
Horse or cattle manure 12" or Chicken litter (contains manure + bedding) 8"
Straw 2-4"

Then turn it under in the spring with your tiller since you already have it. Rake a bit smoother and mark your beds.

We've chosen to garden organically and do use a granular organic fertilizer in addition to manures and compost. Our rainy climate just washes nutrients away, so the fertilizer makes a huge difference now that we've been doing that, too. If you want to use miracle grow synthetic fertilizers you would still benefit from preparing the bed with the manure + straw. Too much fertilizer is going to build up the salts in the soil and not be productive in the long run. More posts on that on GW, too.

2. decide on style of gardening bed for your 6x25 space
There are varying opinions on whether to do wide rows, square foot gardening or other intensive planting. Your 6 feet would be too wide for one bed, so if divided in the middle by a 2foot path you are left with 2feet wide beds on each side. It's hard to sacrifice that space, but you will need to plant, water, weed, stake, harvest, pick off bugs, etc. There's another forum for square foot gardening and a lot resources on the web as well. It is a simple method that you could try without having to commit to it year after year. The making of wooden boxes is optional. I've gardened both ways & whether box or not I do favor permanent beds where no foot treads. I renew each bed after harvest with more compost or manures.

When you're starting out you don't realize the quantity needed at first & it's hard to imagine how much a bagged product will spread.

You can google compost calculator & figure out the cubic feet or yards of what you need bagged or bulk in pick up truck.

In subsequent years you can add manure again only 6" depth in fall or as composted in spring or alternatively compost only to maintain organic matter in your soil. It is amazing at how much gets used up especially in the early years in a warm climate and productive garden.

3. start a compost pile(s)
If you can set aside an area for composting you may be able to make enough for what you need next spring. 2-3 piles 4' wide tall & deep wouldn't be TOO much. Don't bother to purchase a composter. Just make your own pile. Many ideas on the soil forum. All composters are more $ than they produce. Volume is small and the 14 day compost is kind of a gimick. Can be done, but probably not worth the time invested and taken away from other gardening tasks. The fill it up & let it sit composters as sold by cities are useful to make easy cold compost keeping much of your food & paper waste out of the trash. They won't produce enough for your gardening needs.

To make enough compost for your garden you will probably need to import some compost ingredients: used coffee grounds, fall leaves, lawn clippings (without herbicide residue), shredded office/newspaper/cardboard, vegetable garden scraps (avoid cabbage composting cabbage family plants), and manure again.

4. start with easy vegetables 1st
Buy transplants for harder to grow plants like tomatoes & peppers. Planting seeds are a bit trickier to keep moist, plant at correct depth, spacing, etc. Homemade seed tapes can make it easier. Sometimes we've planted transplants as well as start from seeds for lettuces, broccoli, cabbages, etc. Makes a quick garden when you're transplanting and after all that work you've done you will feel like you've accomplished something when you have plants in the ground instead of seeds.

Your climate should grow beans like crazy. Bush beans don't produce as much as pole, but don't need a trellis if planted 9 to a square foot. They will flop some, but are mature in 60 days. You can do multiple crops and just turn the spent plants into the soil then rake a bit smoother on top before replanting something else or more beans. The beans improve the soil by fixing nitrogen. They won't crop without watering though.

5. decide how to water consistently
Soakers are simple to install if you divide your plot into 2 long beds. Run a 50-60' soaker up & down each long bed. Connect the 2 to a splitter or if doing more watering in the yard a 4 way manifold. Probably only enough water pressure to do the 2 soakers at a time. Soakers go under mulch and need to touch the soil. If under mulch lasts longer as sunlight degrades them. You can research more about them.

Drip irrigation wastes less water. Be sure to water deeply rather than a few minutes daily.

Sprinklers waste more water & overhead watering can cause powdery mildew as well as forceful spraying damage young plants.

Hand watering keeps you observing plants closely and you know how much each gets, but will take a huge chunk of time in your climate, so probably not recommended.

I have a dry summer climate and have been experimenting with soakers for various crops. Absolutely successful for tomatoes, cucumbers, zucchini, raspberries, strawberries, and beans. I have some other beds with mixed greens, so I give lettuces hand watering now & then when my finger poke test tells me they need more water. The water keeps the lettuces from getting bitter.

6. Include family members
If you have them include everyone, give a section of the plot or a type of crop to them to take care of. That way everyone shares the duty and work. You can burn out quickly if you're the only one. Remember the little red hen story. Countless times I've felt like that red hen in the middle of summer when the garden is demanding too much of my time and other family members are elsewhere enjoying summer sunshine! I watch my attitude and create a to do list that they can do on their schedule throughout the week without demanding their help immediately. In my passion for gardening I've forgotten that it's a chore for most people not fun.

When they grow a crop they like they have more interest in the garden & make decisions, too. You have to let them make some choices & live with the consequences.

Our daughter started the strawberry patch in a large container with just 2 plants when she was 10. Then we moved those out of the planter and into the ground. Continuing to let runners root and spread the patch to now be 2 double rows of over 50'. She has some of the offsets growing at her place now.

Our son liked the large zucchini leaves, so I put him in charge of hand watering them along with tomatoes & cucumbers. Next to each plant we buried bottomless coffee cans, 2 liter bottles upside down, and milk jugs to direct his 8 year old exuberant hose action. It worked for him to have the job, but I also assisted with installing hose guides, helping move the hose, telling him to check the soil for moisture, the night before a morning watering reminded him tomorrow was watering day, etc. I snuck in climbing morning glories & nasturtium seeds, so he was surprised when he saw new plants coming up. Then when the flowers opened he was even more surprised because they were a mix of colors. Kept his interest to see what was blooming that day.

I hope these ideas help you off to a great start. I didn't intend to write an essay, but wanted to give you some starting advice.
Corrine

If you were in or near some country, it would be useful to get some manure from a local. If in the city then its bags of whatever from home depot.

And I agree that a large tiller seems like overkill for a small area like that. And worse, it might not even dig down now like you would wish. Of course, this may depend on where you actually are.

Thank you all;
George