Growing Concerns 244: Flower garden preparation

I have a 27' x 30' garden plot with a southern exposure. I plan to use it mostly for flower garden and maybe some vegetables. Right now it is entirely grass. How do I get it ready? Should I dig up all of the grass and then double dig, or should I rototill to loosen everything? Do I do a soil test after I have the grass up or before? Do I need to add mulch, and if so, when? The site also slants south, so should I bring in more soil to level everything off?

Can I plant flowers right away or do I need to get the site ready now and keep working on it over summer and wait until next spring to plant? Also, at the end of summer when my perennials die down should I cut them back or wait until spring and clean everything up then? - K.S. -

For a great bed right now

To quickly turn grass plots into flower gardens, dig out the sod. Alternatively, apply a non-persistent, systemic herbicide such as Round-up, wait until the lawn dies, and till it in. Whether you double dig depends on soil condition below the sod.

Double digging is to loosen, lift, and set aside the top eight or ten inches of soil, loosen and improve the underlying ten inches, and then put the topsoil back in place. This is useful when soil is compacted. It's not necessary where soil is already loose and well-drained to a depth of at least eighteen inches. If a compacted bed is bordered by higher, equally-compacted soil that won't be loosened, don't double-dig. The bottom layer of the double-dug bed will become the area's low point and excess water from surrounding areas will flood it. Make a raised bed instead of this root-rotting bathtub.

If you remove all sod and weed roots and loosen the soil as needed, you can plant right away.

Do a soil test now. Go to your County's Extension office to buy a test kit, or call to ask the cost of having one mailed to you. (County Extension offices are listed in telephone directories under county name.) You'll send the test sample and by early May fertilizing time you'll have results -- complete with fertilizer prescription for your bed.

Mulch is a good cover for a working garden. It cools the soil during summer, keeps it from freezing so deeply in winter, conserves water, suppresses weeds, and its decay enriches the soil. Yet it's not essential. Many people do without -- those who don't mind extra weeding, have no problem keeping beds evenly watered throughout the year, and don't mind replenishing depleted organic matter and nutrients with regular additions of compost and fertilizer. What you decide to grow affects mulch decisions, too. Though we don't like the extra weeding necessary until plants grow together to shade out weed seedlings, we don't mulch annual flowers since we find they grow better without.

A south-slanting site can be a great asset. Sloped more toward the low spring sun than a flat or north-sloping site, it catches sunrays more directly, warms earlier, and can be worked sooner in spring.

Slower preparation tactics, less muscle required


If you have patience and prefer to employ Nature's muscle in place of your own, you can start a bed now and have it ready to plant by early fall -- an excellent time to plant everything except annuals and warm-season vegetables.

Slow, easy bed preparation can start with a simple trench dug around the bed, removing sod to the depth of its running roots and flipping it upside down in the middle of the bed. The trench isolates plants outside the bed from those within -- making an effective air barrier roots can't breach. Then smother the grass in the bed area with mulch six inches deep or deeper. A layer of newspaper, several sheets thick, put over sod and under mulch can speed the process.

Keep the bed well watered all summer so worms will keep working in it -- churning together mulch, dead sod and soil. If that soil was well drained to begin with, no other bed preparation will be necessary. Started this way in late April, it'll be ready to plant in September.

Decisions about cutting back perennials involve personal taste. We cut some in fall, let others stay until spring because we like their winter appearance. In beds meant to harbor butterflies and beneficial insects, we don't clip back at all until spring, and then cut slowly and late to allow overwintering insects a chance to emerge from that protective cover. Our book, Caring for Perennials (Storey Communications, 1997) explains cutting back, when and why, in more detail. You can find a copy in many local bookstores and libraries or keep reading here on our website or ask questions on our Forum.