GARDENING : REBECCA'S RULES FOR A FULLER GARDEN, LIFESTYLE.

Byline: Joshua Siskin

Rebecca Lovejoy grows rhubarb in Reseda. ``Never eat the leaves,'' she advises. ``They're poisonous.''

Lovejoy has lots of hints about gardening. Above all, she admonishes you to minimize your spending. ``You can get whatever you need for nothing or next to nothing,'' she says.

She should know. In December, she moved into her Reseda house, ripped out the weedy back lawn, and now has a parterre garden, whose beds are overflowing with flowers, riotous with rhubarb, and will soon be choked with artichokes. And she did it on a shoestring budget.

Lovejoy is so proud of her achievement that she cannot resist sharing what she has learned. She has even taken the time to spell out her philosophy in a monograph on how to garden in the Valley, which, as anyone can see, has universal implications. ``Rebecca's Rules'' are:

1. Make your garden by yourself and benefit your health. Exercise is good for you. Why pay $30 a month for a gym? Your garden is your gym. Want a power workout? Dig up your back lawn like I did.

2. Get your equipment at garage sales. It's so inexpensive, it might as well be free. My mower, shovels, trowels, clippers and wheelbarrow are all from garage sales; their total cost was less than $25.

3. While walking your dog, think like a plant propagator. When you see an interesting flower, ground cover, shrub or tree in someone's yard, knock on the door and ask if you could have a few seeds or cuttings of ``that lovely plant.'' No one can resist such a compliment. Then invite your neighbor to come to your house and offer, in exchange, seeds and cuttings from your own plants. In addition to acquiring a garden full of exotic plants, it's a great way to get to know the people on your block.

4. A lawn is wasted space. If you must have a piece to sit on for contemplation or tanning purposes, save a small square of it. As for the rest, cut and dig it up, and then stack it like sod upside down in the shade of a wall or fence in a far corner of your property. Add manure - you can get it free through the Recycler - to your sod pile and turn it over as often as you wish, keeping it moist. Your old lawn will gradually crumble into several years' supply of compost. If the kids want to play ball but you have no lawn, send them to the park and save on fewer broken windows. If the dog wants to run, take him to the bark park or run him down the sidewalk when you do your plants-for-propagation patrol. That lawn space is for far more serious business, such as growing your own groceries. Once you have planted flowers, vegetables and berries in that formerly grassy space, you will conclude, like me, that a lawn is just plain frivolous.

5. Lawn clippings in that green trash can are an abomination in your new religion, which regards yard waste as potentially holy compost. To prevent your neighbors from sinning - you are your brother's keeper, after all - remove their sacred clippings for the trash and mix them in with your own compost. Of course, you will also want to add fruit rinds, vegetable peels, tea bags, and coffee grounds to the composting heap.

In Woodland Hills, Sipping Pappas has come up with some simple, yet elegant, landscaping ideas. On both sides of a driveway that must be 100 yards long, she has created a hedgerow of the violet flowering society garlic (Tulbaghia violacea) interspersed with pink shrub roses. This project took many years to complete as she divided and redivided what began as a few society garlic clumps and propagated her roses from cuttings.

Pappas has also done something quite remarkable with Madagascar jasmine (Stephanotis floribunda). She has it growing along the south side of her house as a massive wall covering. It started on the ground floor and has since made its way to the second story. The Valley is supposedly too cold for this plant with the large, intensely fragrant, five-petaled white flowers; yet clearly, under the right conditions, it will thrive here.