Marianne Binetti: Hearty plants can take the chill

May 2, 2012 

With the start of May comes an all-hands-on-deck mentality – it’s time to plant those pretty flowers you love. This week, fill your container gardens or window boxes with weather-resistant annuals and flowers.

For container gardens and window boxes, it’s time to plant bacopa, lobelia and petunias.

The most weather-resistant and adaptable annuals that will now thrive outdoors are pansies, violas, lobelia, alyssum, bacopa, vinca, and dianthus. Add more color with the silvery foliage of “Dusty Miller” or deep purple leaves of heuchera, “Black Scallop” ajuga, black mondo grass or hardy perennial plants mixed in with your annuals.

Wait a few more weeks to set out heat-loving annuals, such as zinnias, marigolds, impatiens and coleus. These could suffer from the cool nights even if they don’t get hit by a frost.

Most hanging baskets will thrive outdoors this time of year but only if they are under the protection of roof eaves or covered patios. All plants grown in a comfy greenhouse appreciate some “hardening off “ or gradual introduction to the cold cruel world. Bring them home but keep them protected the first few nights by moving them into a garage or under cover. If a late frost or hail storm threatens, drape a sheet or other light covering atop the plants.

Q. I am going to give a rhododendron as a gift. What variety do you recommend? – S.H., Tacoma

A. What a lovely idea – rhododendrons are one of the best shrubs for our climate and they are evergreen. Some bloom in the shade and in the right place will live for years with very little care. For deep shade and early bloom nothing beats the pink “Christmas Cheer” rhodie and for windy or hot locations lavender “PJM” thrives with attractive burgundy foliage. For small spaces, the compact “Scarlet Wonder Dwarf” is a slow growing charmer under three feet tall and then there are the weevil resistant “yak” rhododendrons such as “Yaku Princess” or the furry and chunky “Teddy Bear” rhododendron. The yak rhodies have compact and tidy growth forms and leaves that have their undersides covered with a densely hairy and soft “fur.” It is this furry texture that makes the leaves more resistant to insects. Enjoy your search for the perfect rhododendron – you can’t choose wrong even if you simply pick a plant with the best-looking blooms.

Q. My question is about an old lilac shrub. The winter ice storm split and broke many stems and it has not been blooming well for years. Should I cut it to the ground? Dig it up? Help! – W., email

A. Lackluster lilacs can be renovated with an extreme makeover. Grab a saw and chop it all down. You’ll soon see new shoots. After a three-year wait, your lilac could bloom again. Pruning right after blooming is the general rule of green thumb. You might also consider replacing your weary lilac with a fresh new variety. Life’s too short to put up with ugly plants and plants are not like children – you do not owe them a life time of commitment.

New and improved lilacs shrubs include the compact dwarf “Miss Kim” the repeat blooming “Bloomerang” that flowers once in the spring and again in the summer, and the more shade-tolerant “President Lincoln” lilac. You can find lilacs in white, pink, deep purple and even wine-red colors. Lilacs love full sun, wind and good drainage. For the best blooms, do not over-water your lilacs.

Q. I love lavender plants. Can I grow lavender in the shade? – S., email

A. Don’t even think about it.

Q. I have a nandina domestica, or heavenly bamboo plant, that has grown taller, but the lower half of this shrub is leafless. Plus, I see some black stems. What should I do? – R.T., Buckley

A. Get some courage, sharpen the saw and cut that baby down to a few stumps. Nandina, hebe, spiraea, and plenty of other winter weary shrubs will reinvent themselves as healthy, happy plants after a drastic spring pruning.

Q. What perennials or plants that are easy to grow should I plant in a shaded area? There also are tree roots so the soil is dry. Nothing wants to grow in this spot. – C.B., email

A. Dry shade is tough for most plants, but if you add some compost and water, the first year you’ll have some luck with lamiums, heucheras, euphorbias, vinca, pachysandra, sword ferns, and a new golden sedum called sedum “Angelina.” Plant some rocks and boulders as well. You can’t kill a good rock.

Marianne Binetti is the author of “Easy Answers for Great Gardens” and eight other gardening books. She has a degree in horticulture from WSU and will answer questions from her website at binettigarden.com.

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