WHEN TO SAY GOODBYE
It’s now autumn, so which plants can you bring inside?
Apologies to the Clash, but it’s time to decide: Should it stay or should it go now? Fromthe canna planted by the corner of the porch in spring to the hanging basket of petunias perched nearby, many plants that provide seasonal garden color aren’t winterhardy. But canwe bear to simply compost them when frost arrives?
Dennis Schrader is a veteran plant-stasher, with an inventory of some 1,600 kinds of tropicals, unusual annuals and more, carried over year to year. That expertise— knowing which to overwinter as seed, cuttings or houseplants, and which to keep dormant in the equivalent of a root cellar, and at what temperature and humidity— is at the foundation of Landcraft Environments Ltd., the wholesale nursery he and his husband, Bill Smith, founded in 1992.
They began theMattituck, NewYork, nursery because Schrader couldn’t find the unusual plants he wanted for the design-build landscape business he had at the time. So they started propagating the plants themselves. One home greenhouse eventually begot a farm, and many more.
So should gardeners bother trying to save the plants they’ve been laboring over all summer or just buy replacements come spring?
Each species has particular overwintering requirements, and theymay not match conditions you can provide. But Schrader suggested some strategies to try— and offered some tough love (gulp!) on what to say goodbye to.
Save some seed
True annuals— plants that go fromseed to setting seed in one growing season — are good beginner candidates for seed-saving, Schrader said.
If the plant forms a pod, it will eventually split open and disperse the seed. On Nicotiana, for example, the little pods on the flower stem discolor fromgreen to yellow, then tan, then brown. Brownwould be very ripe— meaning the tiny seeds may have spilled already. Too late.
With a zinnia or marigold, seed forms in the fading flower’s base, “so when its petals are falling, it’s getting to be time,” he said. “Split a couple open and see.”
Let the collected seed dry for a few days to a few weeks, then store it in a cool, dry and dark place, in labeled baggies or envelopes. Check it occasionally to make sure grain moths haven’t gotten in, and for signs of decay.
Take some cuttings
While it’s tempting to carry annual pots indoors for winter, it’s often better to take cuttings. Try this with coleus, sweet potato vine (Ipomoea batatas), Impatiens, Alternanthera, Tradescantia, either rhizomatous or cane orwax begonias, and ornamental sages, including Salvia leucantha.
“Get out therewell before a frost and start taking cuttings,” Schrader said. First, pinch off any flowers or buds. The length of the cutting depends on the plant, but should average 2 to 3 inches.
Often, the bottom set of leaves will need to be removed. Some— like coleus and sweet potato vine— root readily inwater, but a cell pack filled with potting soil is better. Let the cuttings sit overnight before sticking them in the medium, with the lowest node belowthe surface. Rooting hormone can also be used. A bright, warm spot hastens success; youmaywant to call your seed-starting lights into service.
Mist regularly or, better still, put a plastic bag over the cell pack to make a minigreenhouse, which will reduce wilting and protect the cuttings from drafts. Snipping large leaves in half crosswise also reduces moisture loss.
“Don’tworry if cuttings wilt by day,” Schrader said. “At night, they’ll perk up and get more turgid. Then, suddenly, they stay upright all the time, a hint that they’re starting to root.”
Storing dormant bulbs and tubers
Tender plants grown from underground, bulblike structures will require a rodent-proof, frost-free storage space that is cool (about 40 degrees), dark and not damp— aswell as your openness to experiment. Cannas, dahlias, gladiolus, calla lilies and pineapple lilies (Eucomis), and some elephant ears (Alocasia and certain Colocasia) could overwinter there.
Not all cellars, garages or exterior bulkhead doors are created equal. Learning howcold yours gets, and howdry or humid, may involve some mishaps.
Wait until a hard frost wilts the above-ground parts, signaling the bulb belowto shut down. Then cut the plant back to the ground and dig carefully, starting maybe a foot from the stem. A pitchfork or digging fork is less invasive than a spade, Schrader said.
And if you grewmore than one variety of any of the above, be sure to label them carefully.
Lay the plants in an airy spot out of the sun for about aweek. Then stash them— in milk crates, plastic laundry baskets or even net bags, which are good for hanging gladiolus or dahlias. Some gardeners separate bulbs that form big clumps into smaller ones before storing them; otherswait until winter’s end.
Treat some like houseplants
Maybe the easiest holdovers are those you can treat like houseplants, including non-hardy ivy and ferns, Plectranthus, elephant ears in the genus Alocasia, cane-type angel wing begonias, Tradescantia and flowering maple (Abutilon).
Don’t feed them in winter, Schrader said, and allowthe soil to dry a bit betweenwaterings: “You don’twant to push active growth, but rather to match your care to the reality of shorter days and lower light.”
Check incoming plants for insects, or a slug curled up in the pot’s drain hole.
Another piece of advice: A phased approach over a
couple ofweeks is easier on a plant than being left outside till near-frost and then suddenly being brought into a dry, heated home.
Farewell, my lovely…
For non-hardy plants with high light requirements and those inclined to insect infestations or otherwise likely to sulk in human-contrived environments: To the heap with them, an exercise in letting go.
Sadly, those petunias and Calibrachoa are on the list that should go now, Schrader said, as is heliotrope, Bacopa, Lantana and Fuchsia— and also that current darling creating a silverwaterfall effect cascading over many a pot rim, Dichondra.
With all of them, he is pragmatic. “I’m not saying someone hasn’t succeeded,” he said, “but … I think buying a new one next year will be easier.”