Ask the Clark Gardener

Chrysanthemum—the quintessential fall flower

Roellyn Armstrong, MG

Call it a Chrysanthemum x morifolium, or a Dendranthema x grandiflora, nothing says fall to me better than the bright yellow, russet, orange, gold and burgundy petals of the chrysanthemum. Whether you put one on your front step or you sink ten or twenty in your flower beds, these flowers are always a pretty way to welcome autumn. And why are these flowers so evocative of autumn? Well, aside from their fall-like color palette, these flowers are horticulturally termed short day/long night plants as they require a minimum of fourteen hours of darkness for eight weeks to initiate the production of flowers. And autumn is when we begin to experience shorter days and longer nights. So you may then wonder how it is that we can enjoy these flowers well before the days shorten that much.

Professional growers know the light and darkness requirements of the mum, and they can successfully control the light and darkness at any time of the year through artificial means to force the flowering process. When the days are naturally longer than the plant requires for flowering, (March 15 through September 15) the grower will simply cover the plants with black-out cloth from approximately 4 PM to 8 AM to artificially create an 8 hour day and a 16 hour night. So, if we are getting flowering plants in September for our fall flower beds, then we know the grower had a hand in the flowering process. (Incidentally, this is a shorter day than ever occurs naturally on Long Island.) If the flowers are desired when the day lengths/night lengths are appropriate, no such screening is necessary. Basically, the reverse holds true for plants that are long day/ short night flowering, and the grower must then provide artificial light if the days are too short for the flowering of the desired plant.


Getting the Garden Ready for Winter

Roellyn Armstrong, MG

If you, like me, like the quaintness of the expression of “putting the garden to bed,” then I am sure that you also like the notion of a comfortable “sleeping” period for the garden. And while the garden is never truly asleep, most growing things are dormant and resting. The reason I think I like the thought of my garden in bed asleep probably derives from my satisfaction at having all things put in their proper places before the onslaught of a severe winter, whether or not this will be the reality. I confess that I like to put way the outdoor furniture, clean the flower beds, wash the windows one last time, remove all garden ornaments and prepare for a hunkering-down mentality. (Chalk this up to my need for order and neatness (and also, probably, one could argue, control.)

As we get closer to our first frost, there are many chores to be done in and around the garden. Here is my list: (I am sure there are other things to be done or just neglected, as the gardener sees fit.)

  • Water the lawn and shrubbery well before the first real cold, unless we have had a wet fall. (Proper hydration for your plants will help them avoid wind and cold dessication.) Even consider spraying an anti-dessicant on sensitive plants. Read directions as the temperature is important for this.
  • Drain everything with water, including bird baths, hoses, pots and ponds, unless there is a heater or continuous flow of water. Store all porous, breakable ceramic pots and planters indoors or upside down so water cannot collect. Clay pots may still freeze, so they are best stored indoors. Remove hoses from the house spigot as this prevents freezing at the water line. Bring hoses into a garage to reduce wear from cold exposure.
  • Turn off automatic irrigation systems before frost and drain line with a compressor. Simply turning off the water is not enough as the water in the system will freeze and possibly rupture the line. Disconnect the drainpipe that feeds the rain barrel and drain barrel. Leave spigot open.
  • Pull up all annuals after frost and compost unless there is evidence of disease or mildew. If so, bag and dispose of in the garbage.
  • Lift all tender bulbs, corms, and tubers for winter storage. (I store my caladiums, alocasias, colocasias (elephant ears), bananas and cannas in peat moss after thoroughly drying them. I pull them up after a light frost and clean the foliage off and allow to dry before storage in my heated garage.)
  • Secure and cover outdoor furniture, or better yet move it into the garage or basement. Remove cushions, wash and store.
  • Consider rejuvenating the lawn—fall is the best time to sow seed as long as the seed you select will germinate before frost. (Kentucky bluegrass is one popular seed that requires 30 days for germination.) Keep seed moist until germination. (Remember this before you turn off your sprinkler system.)
  • Order spring bulbs (and try to remember where you planted them last year!) Plant as soon as bulbs arrive as bulbs ordered for the Northeast have not been precooled and require at least eight weeks of cold underground for proper bulb development.
  • Clean and store garden tools. A wiping of cooking oil can prevent rust if tools are stored in a damp area. Drain all power tools of oil and gas. Have blades sharpened. Tune up the snow blower and make sure it works before you need it. Locate the snow shovels and put one in the trunk of the car. Buy some kitty litter or sand for slippery surfaces. (These make a mess but are better for the landscape and cement than the snow melt.)
  • Rake and compost leaves. Consider leaving some in flower beds around shrubs as winter insulation. Wrap arborvitae to prevent splitting with heavy snow coating and tie other evergreens that may also split under the weight of snow.
  • Mulch perennial beds after hard frost to maintain even temperatures and prevent heaving out of the ground if there is a warm period.
  • Buy birdseed and begin feeding the birds. Try to have a water source for them as well. (I leave the pump on my stream running so there is always fresh water.)
  • Put your holiday lights on the shrubs now when the weather is still pleasant, and the shrubs are not brittle. (You’ll feel so smug when you see your neighbors out there in the freezing cold.)
  • Trim the evergreens as needed to have greenery for indoors for the holidays.

Back to top

The Poinsettia

The Poinsettia

Roellyn Armstrong, MG

There is probably no other flowering plant that has come to symbolize a holiday better than the poinsettia. Decked out in the Christmas colors of red and green, it is a perfect choice to accent a holiday décor. But what do you really know about this plant? And do you really think you want to keep it on for reblooming next year? Known botanically as Euphorbia pulcherrima, the plant we call poinsettia is a woody shrub or small tree in its native habitat of Mexico and Guatemala, where it can reach a height of 13 feet. It is named for the first United States Minister to Mexico, Joel Roberts Poinsett, who is credited with the introduction of the plant in 1825.

The plant part that we think of as the flower petals is actually the colored bracts or leaves of the plant and can occur in orange, pale green, cream, pink, white or marbled, besides the flaming red we most associate with the plant. The actual flowers of the poinsettia are unassuming. They are grouped within small yellow structures found in the center of each leaf bunch, and are called cyathia.

The colorful bracts are created through a phenomenon known as photoperiodism, the same process that was described last month in the article about bringing chrysanthemums into bloom. Poinsettias, short day/long night plants, require darkness for the bracts to change color. At the same time, the plants require abundant light during the day for the brightest color.

The plant requires a daily period of uninterrupted long, dark nights followed by bright sunny days for around two months in autumn in order to encourage it to develop colored bracts. Any incidental light during these nights (from a nearby television set, from under a door frame, even from passing cars or street lights) hampers bract production. Commercial production of poinsettia has been done by placing them inside a greenhouse and covering them completely to imitate the natural biological process.

Sit back, sigh, enjoy your hot cocoa, and begin your own hibernation after so much work!


Remember, if you have a comment or question, send them to me at And come for a visit!

Back to top

Support the Garden

Annual Fund Drive

Clark Botanic Garden needs your help.

Please help us maintain our programs and preserve the Clark legacy as a thriving botanic garden by contributing to the Fanny Dwight Clark Memorial Garden, Inc. Annual Fund. The garden's success is directly dependent on your generosity.

»About the Fund Drive | »Donate Online