Spongy soil may require double-digging

Q: I am attempting to create a new flower bed out of an area of lawn that probably has grown only grass in the past 125 years. The soil is like sponge (similar to peat moss). The rototiller jumps up and down when I try to dig. What should I do?

I have another problem. Last year, we were told that a particular seafood compost was the very best for all of our growing needs. A large amount was purchased and much to our dismay not even lowly weeds will grow in this mixture this year. Do you have a solution? – A.A., Milbridge

A: To address your first concern: The spongy area sounds like an ideal candidate for what’s called double-digging. This procedure is a lot of work, but well worth the effort if you want a high-quality soil in your flower bed. Double-digging is a manual job unless you want to hire a backhoe, which might be warranted, if the project is large enough. Double-digging is performed by excavating the soil to a depth of about 1 foot. This soil is placed aside on a tarp and the next foot or so of the soil profile is dug out and placed aside on another tarp. The first foot of soil that was removed is then placed at the bottom of the trench and the bottom foot of soil removed is put on top.

Essentially, you see, you dig deeply and replace the topsoil with the soil from the lower portion of the soil profile. The new, fresh, nonspongy soil should then be amended with organic matter and perhaps lime. (Again, soil-testing would be wise.)

Once the double-digging is complete, rototill to your heart’s content!

As for your second concern: without knowing what brand you purchased, I dare only to make a general comment. Typically, bagged compost (perhaps you purchased yours unbagged in bulk?) shows the chemical and physical properties of the product. This information is useful in deciding how to apply it to amend soil.

Why did the material yield such a poor plant response? Perhaps the supplier didn’t properly compost the material. If the organic material had a strong or unpleasant odor, that could indicate that the composting process was incomplete. A poorly composted product may contain a high level of nitrogen, resulting in “burning” and thwarting plant growth.

Other factors, including pH and other physical and chemical properties of the compost, could affect plant growth. It may be worthwhile to ship off a sample of the compost to the University of Maine analytical lab (through a kit supplied by your local Cooperative Extension office). This will cost a fee but will provide some scientific analysis as to what exactly the product contains.

Q: I’m a sporadic gardener. I can usually get along OK with annuals and perennials but I am slightly stumped by biennials. I purchased some beautiful hollyhocks at a yard sale a few years ago and put them in. They grew and were lovely but the next year I didn’t see them and thought that they had died. The next year they came up and the year after that they did not. However, this year they have come up and spread. I love them. How can I outwit them so I can have some every year? If I take the seeds and freeze them and then start them inside, will that work? – Jeri, e-mail

A: Sometimes a biennial’s life cycle is somewhat difficult to outwit. Although technically speaking this group of plants is supposed to produce leafy, vegetative growth in the first year from seed, and flowers in the second year, some so-called biennials live on and produce flowers in the third year, too. Often gardeners will find through experience or references that hollyhocks – particularly the single-flowered varieties – tend to be “biennials’ short-lived perennials.”

Hollyhocks tend to self-sow very easily. On each tall stalk one may find many individual flowers that produce several dozen seeds. If left to nature, the seed may drop to the soil and lie there – dormant and viable – for an extended period.

Yes, indeed, collect, dry, freeze and sow seed every spring. You may start hollyhocks inside or simply direct sow them in the garden. Perhaps the only way to truly outwit biennials is to seed them yourself every year, ensuring – insofar as it is possible – blooms in the subsequent year.

Diana George Chapin is the NEWS garden columnist. Send horticulture questions to Gardening Questions, 512 North Ridge Road, Montville 04941, or e-mail dianagc@midcoast.com. Selected questions will be answered in future columns. Include name, address and telephone number.