Expert: Long Island Gardener - 10/14/2006

Question
I am in zip code 19522, zone 6, I think, and I had a plant come up this year that I thought was Calla Lilies I planted a while back, but it didn't bloom, upon investigation, I realized my leaves looked nothing like the calla leaves in the pictures here, so how do I know> the leaves are much longer, and much more slender, and more fanned out than the tight balls of foliage I see in the pictures here, and if it is a Calla, did it not bloom because I didn't take it out of the ground last fall, and replant it in the spring? How do I know which of my own plants I should "lift" for the winter as it is put in the catalog I like to dream in? Thanks So much for any help you can give me

Answer
Yup, Fleetwood PA - that's Zone 6 all right.  But even in Zone 6, you have microclimates all over your garden.  Next to South facing foundations, say, or baking near a sidewalk or paved driveway.

It's a stretch, but not impossible to grow Zone 8 plants in your Zone 6 climate. Look at how the snow melts on black asphalt, and then on cement pavement, after a winter storm, long before the melts on the grass.  The snow, however, will insulate soil underneath from weather and temperature extremes.  It's a complicated dance that centers on soil moisture and sun.  If a Calla Lily -- "Zantedeschia aethiopica" or "Zantedeschia elloitiana" -- has managed to survive but not fluorish, somewhere in your yard, maybe the microclimate just needs to be a touch milder.

Right now is the best time of year to study your microclimates.  Get up early for the next 2 weeks and record where frost forms around your garden.  Pockets of chilled air will freeze the dew on leaves over the night; this is not somewhere a Calla will grow and bloom.  Monitor the "weather" at the location of this mystery plant and make careful notes about light and wind exposure, sun angles, wind direction and temperature ranges at different times of the day.

Something as simple as flagstones or a cement porch will absorb solar heat during the day and radiate it back at night, in the dead of winter, keeping soil temperatures nearby more moderate than the rest of the garden, and more Calla-friendly.

You might be surprised by the effect a big tree has on garden temperatures.  Daffodils growing under the drip zone bloom a week earlier than those in open ground.  The soil is slightly warmer there.  Same goes for Southern exposures, which bloom ahead of Northern exposures.

Soil composition (clay, sand, loam): Soil moisture is determined by the proportions of clay, sand, and loam in your soil. Clay holds the most moisture and sand the least, but the air pockets in loam make moisture accessible to plants and make it easier for dry soil to re-absorb moisture.

Precipitation: Total annual precipitation affects soil moisture, but so does the pattern of precipitation--does it all come during a rainy season? are there periods of drought? is there regular rain at least every week?

Local water sources: Local sources of moisture can affect your soil. How deep is your water table? Is there groundwater or surface water nearby?

Drainage pattern of land: Is the site elevated or in a hollow? Does runoff drain into or away from it?

Competition from surrounding plants: Are the surrounding plants water hogs? Do they have shallow or deep root systems? How much will they compete with new plants for water? Knowing the answers to these questions will help you choose good companions for your existing plants.

Overhead foliage or obstacles: Foliage can block a significant amount of precipitation. So can overhanging eaves or other structures. These create drier microclimates under them.

Exposure: Both wind and sun can dry out an area that might otherwise retain moisture. Is the site sheltered by shrubs or lattice, or is it located in a wind tunnel? Does it receive dappled sun or direct sun?

Deciduous trees aren't the only thing that determine how much sun one site will get. Because the sun's position changes between summer and winter, sun exposure in one spot will also change completely.  Don't assume a full sun location is sunny all year round.  The site may be in shade all winter, if it's on the north side of the house.   Another spot may be sunny all winter long, and shaded during the summer, if a maple tree is growing overhead.

Generally, Zone 7 and North, Calla Lilies spend their winters indoors in a dry bed of peat moss or vermiculite in a cool basement or heated garage.

I don't think there's a literate gardener alive who doesn't fantastize about growing everything under the sun.  That's why God invented Greenhouses.  Although there are many plants that have Calla-like leaves, who's to say this is not the Callas you planted, just ekeing out their lives in the frozen Pennsylvania tundra, too weak to form a spathe?  I'd say it's worth it to lift at least a few this weekend and dust them off, then store through the winter and wait for signs of new life.  Potted, perhaps this will bloom, while you're studying the landscape for a Calla-friendly microclimate.  Let me know what happens next!