Large lawn in the Heights? Wow. That's something I don't see after growing up there through high school by 290 and 610.

I suppose that Scott's Organic fertilizer from Lowe's or Home Depot would be sufficient at a minimum. Who cares about the weeds? Just mow high (3-4 inches) and you will be fine. That's what we do at my mom's house few miles from you and it's the greenest lawn on the block during the winter and it's hardly ever watered during the summer.

What kind of garden? Mulching is the best way to conserve the water and improve the soil dramatically. Look for tree trimmers around Houston and ask if they would dump a load of wood chips. That saves you a few hundreds of dollars.

I don't really know where in houston to get compost for free. As far as I'm concerned LETCO (Living Earth Technology) has the best compost in Houston for bulk. It does help a lot. One cubic yard per 1000 sqft is all you need. It's the delivery fee and fuel surcharge that suck so if you have a truck or a trailer with sidewalls, it's great. Fortunately, it's only one time application. All you have to do is feed the lawn with organic fertilizer every 3 months. Nothing to it. There is two organic places in Houston... Wabash feed store off Washington nearby Memorial Park and Southwest Fertilizer off Chimney Rock (i think) outside 610 loop not too far from the Galleria. My preference is soybean meal but I don't know how much they cost there. I think I saw it at Southwest fertilizer but that's over a year ago.

2. Water deeply and infrequently. Deeply means at least an hour in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. If your grass looks dry before the month/week is up, water longer next time. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds.

3. Mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. Bermuda, centipede, and bent grasses are the most dense when mowed at the lowest setting on your mower. Dense grass shades out weeds and uses less water when tall. Dense grass feeds the deep roots you're developing in 1 above.

4. Fertilize regularly. I fertilize 4 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above.
   

Check out the organic lawn care FAQ over on the Organic Gardening forum and see if that helps.

The above post is SPAM.
Spraying, or applying, any kind of "fertilizer" on any plant that is growing in a soil with inadequate levels of organic matter is a waste of your time, energy, and money since without adequate levels of organic matter any nutrients in those "fertilizers" will not stay very long unless there is something to hold them (sandy soils) or will be tied up by the soil (clay) and will not be available to the plants.

Berry,

There is a feed store near you on Main Street that you can get feed from for fertilizer. Soybean meal or cottonseed meal are probably the highest in N (protein) though you can also use alfalfa pellets and cornmeal too.

Here is a link that might be useful: feed store