Ask the Gardener: Plants that work in shady and wet window boxes

Ask the Expert Gardening
Heuchera is a shade-loving plant that can add a pop of color to your window boxes. Adobe Stock

What to do this week: It is now safe to plant even the most cold-sensitive flowers and vegetables, such as impatiens, dahlias, basil, tomatoes, corn, eggplant, okra, melon, cucumber, peppers, pumpkin, squash, watermelon, beans, and zinnias. Water daily for the first week after planting unless there’s rain. Plant or purchase container gardens. Kill invasive weeds before they go to seed.


Q. I have a window box that has become totally shaded by trees. I tried planting impatiens, but they don’t do much. It is so shady that the box rarely dries out; just the rain keeps it wet. Any suggestions? I would love flowers but don’t know what to do!

K.D., Piermont, N.H.

A. Maybe it gets too soggy. You should clean out your containers every year and change the soil. Add a layer of gravel or pebbles at the bottom to keep the drainage hole from getting blocked up by compacted soil. Fill them with small perennials and ground covers with colorful foliage. Try Japanese forest sedge, miniature hosta, dwarf Solomon’s seal, ivy, heuchera, and ajuga with dark leaves. For annuals, try coleus, begonias, and trailing sweet potato vine with purple or chartreuse foliage.


Q. I just bought three bunches of forsythia, but which fertilizer should I get? I have been told, “If the first move is wrong, the entire remains will be wrong.’’

L.W.W., Newton

A. I wouldn’t fertilize at all the first year. The “first move’’ for any tree, shrub, or perennial is really just planting the crown at the exact same level that it was growing in its pot or its previous location. The crown is where the top growth sprouts from the roots at soil level. Many people kill plants by planting the crown too deep. So here’s how to plant: Lay down a tarp. Dig a hole just as deep as the roots but three times as wide. Shovel the excavated soil onto the tarp. Mix in enough compost or aged manure so it accounts for about a third of your total pile. As you backfill, position the plant so its crown is level with the surrounding soil line, and hold it there. Use leftover earth to make a little dam around the plant to prevent runoff, then water deeply. Water new plants at least once a week during dry spells for the rest of the year.

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