Ask the Gardener: Growing sunflowers to show your support for Ukraine
Plus, when to cut back Montauk daisies and dealing with late-blooming dahlias. Get more gardening advice at RealEstate.Boston.com.
What to do this week Another season begins in the garden and of this garden column. Get outside as much as possible and do what you can to enjoy and conserve the natural world, which is beset on all sides by development and pollution. Earth Day falls on April 22, but celebrate it year round by trying to preserve mature trees, which may be our greatest allies in buffering climate change. Because of increasing heat and drought, any mature tree with far-reaching roots that is cut down now is probably irreplaceable, no matter how many baby trees with tiny root systems developers say they are going to replant. It’s not like the old days when you could cut down a large but inconvenient tree, plant a little tree in a better spot, and expect it to grow big in 50 years. Those days are going, going, gone.
Q. The sunflower is one of Ukraine’s national emblems, and I would like to grow some but don’t know how. In Boston, I could certainly plant a little Back Bay front garden with the colors of the national flag — blue and yellow. What do you suggest?
M.M., Boston and Nelson, N.H.
A. I am flying the Ukrainian flag (about $10 from Amazon.com) over my front door above purchased pots of blue and yellow pansies and clear blue greenhouse-grown hydrangeas. To grow annual sunflowers, plant the seeds half an inch deep in full sun outdoors in Boston now or three weeks later in most of New Hampshire.
This website will show the last frost-free date for your ZIP code: garden.org/apps/frost-dates/.
When choosing a location, keep in mind that mature sunflowers face east, toward the sunrise. Water after planting, then weekly.
Ukraine’s sunflowers (Helianthus annuus) have become a symbol of resistance. One recent viral video (8 million views) shows an older woman on an eastern Ukraine street corner shouting at occupying Russian soldiers to put the flower seeds in their pockets “so sunflowers will grow when you die here.’’ Snap!
Related stories
Some of those tall, beautiful sunflowers are not friends to bees. Here’s why.
Sunflowers in October? Re-bloomers create deja vu in the garden
Q. Is it too late to cut back a Montauk daisy? It has a lot of growth showing. Should I cut it back in the fall, and if so, how short? Or should it be in the spring?
J.C., Dover, N.H.
A. It can be confusing. Cut back the dead tops of perennial flowers in the spring all the way to the crown where stems emerge. If you accidentally also cut sprouting new green growth, don’t worry. It will grow back fast. Montauk daisies (Nipponanthemum nipponicum) also need a third of their new growth cut back in May to keep the plants from splaying unattractively when blooming late in the year. A May haircut also works to keep fall-blooming asters, chrysanthemums, and phlox more compact and producing more flowers.
Q. A video said I could start my dahlias early if I had heated floors. I do and it worked! However, they did not bloom any earlier, so what is the benefit of starting them earlier?
P.H., Mission Hill
A. Dahlias are popular fall flowers but often don’t bloom until October. You can give the tender tubers a head-start by planting them in pots indoors now. But these demanding tropical flowers will still be slow to bloom after you transplant them outside at the end of May unless you give them a spot with full sun, enriched soil, and irrigation. If you lack these amenities, try growing shorter dahlia varieties with smaller flowers. They bloom much sooner than giant dahlias. They lack the “wow factor’’ but offer more flowers.
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