Manipulating size of plant aids growth

Q. Last summer I dug up a number of lilacs from around the base of a humongous mother plant near our barn and transplanted them to a new formal garden by the entry to our house. For reasons both aesthetic and sentimental, we prefer these common lilacs to the fancier varieties. They survived the winter fantastically; some of them already have a few tiny suckers starting from their roots.

My only problem is that most of the new plants leave a lot to be desired in terms of shapeliness. How can I prune them so as to encourage an even fullness? For example, some of the new plants are top-heavy with foliage while the lower portions of their branches are bare. I had thought of lopping off all their tops (leaving some foliage) at some uniform height, but worry that this might be too drastic. Can you help? – S.C., Surry

A. By nature, lilacs tend to have what horticulturists term a “vase-shaped” growth habit. This is illustrated exactly in your description of your lilac’s “top-heavy” appearance.

One may manipulate the growth of almost any plant through pruning. Removing the tips of branches with hand pruners effectively removes the growth regulators that encourage upward growth. This action causes branching – and therefore, fullness – below the portion of the stem that was removed.

Removing the tips of branches may also limit the maximum height any given plant achieves. Therefore, pruning your lilacs in an effort to create a more full appearance may cause them to not reach their maximum potential height. You may view this as a fair exchange for more lush looking plants, or you may prefer a very selective, light pruning that will allow the plants to reach their typical height.

In sum, lilacs typically are not pruned for form, but it is possible to manipulate their shape to some extent. The general recommendation for lilacs is to prune for plant health: remove old, damaged or diseased plant material. This type of pruning is undertaken in late winter or early spring before the leaves have emerged. Pruning for shape is another matter, and may be undertaken in summer when the full form of the plant may be considered.

Q. You mentioned angelica in one recent column. Can you please tell me if the plant is edible? I’ve seen it before and remember the fragrance of the stems and leaves. I seem to remember it has some culinary or herbal use. Do you know what it is? – D.M. Mount Desert

A. This wonderful plant has a distinctive anise scent and flavor. Indeed, it is used both medicinally and for culinary purposes.

Angelica’s botanical name (Angelica archangelica) gives clues as to the plant’s legendary ability to provide medical relief and even ward off evil. Historically, the plant was believed to cure many diseases, including colds and lung ailments, rheumatism and indigestion. The liqueur Benedictine includes angelica.

All parts of the above-ground portion of angelica, the stems, leaves, flowers and seeds may be used in desserts and candies. The tender stem tips and leaves may be used in salads.

Q. What do you know about leeks? Can you grow them well in Maine? – A.H., St. George

A. Leeks, like so many members of the onion family, grow well in Maine, if properly cultivated. These vegetables require a 3-month growing season, so it is necessary to sow their seed indoors in spring and set out into the garden transplants.

Seed may be broadcast over a flat of media and thinned to 2 inches between plants. These seedlings may be carefully separated and set into fine, well cultivated garden soil after the danger of frost has passed in spring.

The most delicately flavored leeks are those that are blanched. Blanching is a process by which soil (or another acceptable material, such as sawdust or leaf litter) is mounded over the growing stems, effectively limiting light penetration to the plant tissue and causing more succulent, tender growth. To prepare the plants for blanching with soil, form a 6 inch deep trench in the garden and plant the seedlings in the bottom of the trench at 6-inch intervals. As the stems grow over the early weeks of summer, gently mound the excess soil from then trench around the stems.

Leeks may be harvested well into autumn and until the garden soil has frozen.

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.