Marianne Binetti: With June, comes the summer garden to-do list
With the weather warming, your garden agenda should heat up, too. On your to-do list should be planting warm-season crops, fertilizing and tending your roses. Here’s your task list for early June. I’ll also answer a few reader questions about lilacs and shade plants.
• Plant warm-weather crops: Say goodbye to May and hello to warm-season crops. During the past few weeks, the soil has warmed enough to start planting seeds directly into the soil.
Warm-season crops such as cucumbers, squash and carrots are ready to go into the ground, as are flowering plants such as nasturtiums, sunflowers, marigolds, cosmos and iberis.
• Get fertilizing: Roses, perennials and potted plants need fertilizing this week, but don’t go flinging fertilizer around rhododendrons, camellias, azaleas and most other blooming shrubs. Trees and shrubs do fine without additional plant food and too much fertilizer can encourage soft new growth that is weak and attractive to disease and insects – just like over-feeding humans can make them less healthy. Use a compost or organic mulch around trees and shrubs, or a slow-release plant food.
• Add to your landscape: You can continue to add new trees, shrubs, perennials and annuals to the garden. Just make sure you soak the root ball of new plants before you remove them from the pot and add them to the planting hole.
• Tend your roses: If you haven’t pruned your roses and they are budded up or blooming, enjoy the flowers in June, but then cut back the longest canes after the first flowers fade. You can always remove anything dead, diseased or damaged from a plant no matter the season.
A few questions from readers:
Q: My lilac is done blooming. Do I have to prune off the faded flowers? Also the leaves are curling with some silky threads. Help! – D.F., Renton
A: You can get snippy with the faded blooms of lilacs to promote new growth and better blooming. Lilacs also need to have their suckers, or new growth coming from below ground, removed to keep them from reverting back to wild plants. Shorten the longest branches of your lilac by at least a third to encourage new growth.
Watch lilacs for insect infestation. The curling leaves and silky webs are from an insect called the banded leafroller . If you have just a few leaves infected, remove them immediately and squish the little caterpillar hidden inside the leaf. If more than one-third of the shrub is infected, you can spray with an organic spray called BT, or Bacillus thuringiensis, two or three times over the next few weeks to kill off the worms before they mature into moths. Clean up fallen leaves and debris around your lilac especially in the fall to keep this insect from hiding out in the root zone.
Q: I have a spirea “Magic Carpet” variety growing in a large container. It does very well and blooms most of the summer. My question is how long can this shrub grow in a pot? - S.D., Olympia
A: You don’t need to contain your enthusiasm for this happy shrub because potted spiraes have bloomed happily in containers on my patio for almost a decade. Like Japanese maples, they seem to adjust to the potted lifestyle, but unlike Japanese maples, spiraes look better when pruned back hard early in the spring. I have found that all of the dwarf or compact varieties of spirea do well in containers including the spirea “Limemound,” the ‘Golden Sunrise,” the “Goldflame,” and the beautiful and carefree spirea “Magic Carpet.”
Q: What shrubs will do well in the shade? I have some large trees in my backyard and very little full sun. – C.C., Maple Valley
A: Filtered shade from tall trees is perfect for growing rhododendrons, azaleas, hydrangeas, leucothe, viburnums, euonymous, yews, even blueberries and nandina along with hundreds of other native and new plant introductions. The important thing is to improve your soil by adding organic matter and mulch to the shrubs so that they don’t dry out.
All new trees and shrubs will need regular watering the first few summers that they are in the ground. My personal favorite for summer color in the shade is the hydrangea. There now are so many new hydrangeas available that creating an outdoor room using hydrangeas that rebloom such as the “Endless Summer” and “Blushing Bride” varieties is very rewarding. There also are some new dwarf hydrangeas that are perfect for pots on a shaded porch or patio. You’ll pay more for a patented new hydrangea, but these hardy shrubs are long-lived and carefree – you’ll have it made in the shade.
Marianne Binetti is the author of “Easy Answers for Great Gardens” and eight other gardening books. She has a degree in horticulture from Washington State University and will answer questions at her website binettigarden.com