Transform your landscape with one of these garden designs

By Cliff Johnson, master gardener
Carver and Scott counties

Gardens have taken on a lot of different looks since the days I hoed weeds in between rows of vegetables in a plot of farm ground back in the 1950s. Three garden designs that have caught my attention lately are island beds, raised beds and lasagna gardens.

An island bed is an area of soil placed in a lawn or hardscape, designed in most cases to grow perennials, annuals or herbs.

A critical design consideration for island beds is to create a relationship between the island planting and other areas in the landscape, explains Julie Weisenhorn, University of Minnesota extension horticulturalist. “This can be accomplished through repetition — repeat by the shape of the bedlines. Repeat plant types, especially masses. Repeat color. Repeat materials like boulders, edging styles (brick, pavers, etc.).”

Weisenhorn says island-bed design can take on many different looks. One design may be just masses of perennials. Mix and match these masses by texture and size, and overlap the masses to create a continuous flow of plants. Locate the taller perennials in the middle and work your way down with the shortest plants along the outer perimeter.
Another design may include a specimen tree, shrub or statue in the center of the island for a more formal design, or at one end of the island for an asymetrical design. Be sure to choose a specimen sized appropriately to fit inside the island at its mature width. If it grows over the bedline, it will interfere with traffic and driving (if it is a driveway island planting) or it will shade and kill the turf and make mowing difficult, if it is in the middle of a turf area.

When preparing the soil for an island bed, Weisenhorn cautions against too much soil, since the soil level needs to accommodate 3 to 4 inches of mulch. “You also do not need landscape fabric if your mulch is thick enough,” she says. “When mulching an island planting, use shredded wood mulch (not chips) and dig a trench around the bedline. Because the shredded mulch clings together by its rough edges, this method helps keep the mulch inside the island.”

Lasagna gardening is a nontraditional organic technique that relies on a layering method called “sheet composting.” The name “lasagna” comes from the way garden beds are created using layers — the same way you layer ingredients when making a pan of lasagna. Watering and weeding are reduced through the heavy layers of mulch and by planting crops close together. The lasagna layering method quickly builds soils that are incredibly rich in nutrients, resulting in higher than average garden productivity.

The lasagna garden technique would be one way to establish an island bed. Thick layers of organic mulch are the main ingredients of a lasagna garden. Chopped leaves, grass clippings, straw, hay, sawdust, wood ash, compost, animal manure and newspaper are just some of the materials that might make up layers of a lasagna garden. Individual materials will vary in each individual's garden according to what is available locally.

To make a lasagna garden, stake out a site and begin building up the beds layer by layer. The first layer involves laying down something heavy over sod, like thick pads of newspaper or flattened cardboard boxes (to kill grass). The next layer should consist of 2 to 3 inches of a water-absorbent material like peat moss. Next, a 4- to 8-inch layer of organic material, such as compost, is spread over the peat layer. Another layer of peat or a peat alternative would be added on top of that, and then yet another layer of organic material, like grass clippings. Repeat the layering process until the beds reach 18-24 in. high. Finally, the tops of the piles may be sprinkled lightly with bone meal and wood ash for added phosphorus and potassium.

Lasagna gardens can be planted with perennials or seeded in the spring. For more detailed instructions on lasagna-garden design and construction, search “lasagna garden” on the internet and you’ll find thousands of references.
Raised beds are generally constructed out of wood timbers but can also be made from boulders. They may only be 6 inches or 1 foot off the ground, or raised to waist high.

There are several reasons gardeners use raised beds, according to Larry Cipolla, a Hennepin County master gardener: