Horticultural Q& A - When Shallots Flower, Rabbits Eat Seedlings, Bricks Hurt Azaleas

By Scott Aker
Special to The Washington Post
Thursday, November 20, 2008

Q Last fall I planted shallot bulbs. In late spring, I waited for the leaves to shrivel, signaling they were ready for harvest. Instead, they began to send up flower stalks. Where did I go wrong?

A Shallots love cool weather, so Washington is not the best place to grow them. They tend to flower in response to stress. You can grow a passable crop, however, if you take advantage of the cool part of our growing season. Shallot bulbs prefer to have the first part of their growing cycle cool, followed by gradual warming until they reach maturity by forming bulb clusters. The problem with fall planting is that they grow initially and then encounter the cold of winter. This primes them to flower as soon as warm weather arrives in the spring. Thus, it's best to plant them in December.

You can also plant them in February, as soon as the weather rises above freezing for a few days. If they are allowed to grow in uninterrupted cool conditions, the first hot days in late May or early June will cause the plants to begin to go dormant, as desired. Shallots are typically harvested before mid-June in our area.

Rabbits ate the flowers I started from seed. How do I protect seedlings short of putting up a fence around the beds? We have a fox in the neighborhood that was seen with a rabbit in its mouth, but I can't count on the fox to protect my plants.

The fox may not guard your flowers, but it will reduce the rabbit numbers in the short term and may spare your garden from damage. Blood meal and a number of other repellents may be effective in keeping rabbits away.

Perhaps the damage is not from rabbits but an insect called a cutworm. Cutworms are common pests of a wide variety of plants and tend to do their damage when the seedlings are just beginning to grow their first set of true leaves. Cutworms are easily controlled by placing a paper collar around new seedlings to serve as a barrier. Disposable paper cups that have had their bottoms removed work well.

I have an azalea bush that has done well for years, but this year much of its leaves turned brown. A neighbor said that this was because I placed bricks around the area and that azaleas, as acid-loving plants, don't like bricks. Is this also the case for hollies?

If the bricks were used as an edging, it is unlikely that they would be harmful. But if you paved a large area above the azalea's root zone, the bricks might have an effect. Bricks can absorb sun and make for a hotter, less hospitable climate for your azaleas. And as paving, they may have compacted the soil, leading to the death of the roots and eventually the leaves.

The same is generally true for holly, although it tends to be a bit more tolerant of soil compaction than azaleas.

You didn't mention mortar. If your bricks are cemented, the mortar would certainly harm the azaleas and the holly. Mortar contains lime and will raise the pH of the nearby soil, particularly right after it is installed. High pH is deadly to azaleas.

If this is the case, the damage has been done. You may want to plant a replacement shrub with a tolerance for the higher pH, such as a yew or a viburnum.

Scott Aker is a horticulturist at the U.S. National Arboretum.

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