Just How Cold Hardy is Lettuce Anyway?

Newly sprouted lettuce in my
garden on Nov 25th.  It
easily survived the freezing
temperatures last night.

Here in Southeastern North Carolina lettuce is a winter crop, or at least a cool-season crop avoiding the 5 months of the year (May - September) that can rightfully be called summer.  I first grew winter lettuce several years ago and treated it like it was a tender summer garden plant, dutifully covering it with glass frames and old bed sheets on sub-freezing nights.  The lettuce grew and prospered under that treatment, seemingly confirming my belief that I had to do all that work to get lettuce to grow well in the winter.

Then last winter I neglected to do anything to my lettuce on the coldest night of the year.  The temperature got down to 20 degrees Fahrenheit. (-6.7 degrees C)   What did I find the next morning?  Perfectly healthy lettuce plants that continued to grow and grow into the Spring.

I don't know if this is true with all varieties of lettuce but it seems that for the varieties I'm growing, their ability to handle cold winter temperatures is nearly as good as hardy brassica and related species like Mustard Greens, Collard Greens, and Kale.  I've also grown Spinach under the same cold-weather conditions with an equal degree of success.

Once the weather warms in earnest by late April, each lettuce plant grows a tall flower stalk that produces a copious number of seeds.  This flowering process is often called bolting.  Once ripe and dry, the seeds can easily be stored over the summer and replanted in the fall.  Many authorities suggest that lettuce leaves acquire a bitter taste when the plant is bolting.  I haven't observed this bitter taste develop myself, but when the plant is old and large enough to bolt the remaining leaves are usually so thick and tattered you wouldn't try to eat them in the first place.

Lettuce growing in my garden in mid-February, 2012

Mixed lettuce varieties, mid-February 2012.

First Fall Freeze

Cold weather has finally arrived in Southeastern North Carolina.  The first freeze of the season took our temperature down to 27 degrees in my backyard yesterday morning, with 29 degrees recorded at the nearby Wilmington airport.  Here's a graphic I made at work yesterday showing the end of the growing season in Wilmington and some statistics for the 2012 growing season:

2012 Growing Season statistics for a portion of eastern North and South Carolina served by the NWS office in Wilmington, NC.

This freeze spelled the bitter end of all of my summer vegetables and herbs including the peppers, tomatoes and basil.  I've saved plenty of seeds from all of these to replant next spring.

The leaves and flowers on our backyard Lantana bushes were killed as always happens with the first fall freeze.  The remainder of the plant is much more cold-hardy and will spring back to life next year.  Roots of these lantana bushes have survived at least 15 degree air temperatures back in 2002 and then successfully resprouted the following spring.

Lantana, before and after the freeze

A freeze-damaged limb on an Owari Satsuma. 

Soil temperatures have been steadily falling for the past couple of months.  Once soil temperatures fall below 55 degrees Fahrenheit, dormancy develops in all of my citrus trees.  Winter dormancy is actually a very good thing since it gives citrus trees the ability to survive moderate freezes with no damage to their leaves or branches.  An actively growing "awake" citrus tree will sustain heavy damage with air temperatures in the upper 20s; yesterday morning's 27 degree low temperature froze only a tiny amount of late, tender growth on the outermost branches.  I try to prevent my citrus from producing new growth late in the year by not applying fertilizer after the end of June.





I wish I could grow edible bananas here.  I've experimented with several banana varieties reputed to be cold-hardy including Misi Luki, Red Iholene, Ice Cream, Dwarf Cavendish, and Williams.  None of those varieties survived the cold winter of 2010-2011 which literally froze the top few inches of soil in my backyard -- something I never thought could happen here.  The only banana variety that did survive the mayhem is Musa ornata, an ornamental variety that continues to reliably produces beautiful flowers each summer.  The flowers yield small green bananas along a long stalk during the summer and early fall, but given the limitations of our climate they never grow to more than 4 or 5 inches in length with a diameter around 3/4 inch.  Bananas also become dormant with cooler fall temperatures, although unlike citrus they cannot develop an ability to sustain sub-freezing temperatures even in their dormant state.

Musa ornata bananas in my backyard during mid-summer (left) and after our recent hard freeze (right).
The underground corm is now dormant and will sprout new banana plants next spring.

The Red-breasted Nuthatch, and other backyard birds

An unusual bird for Southeastern North Carolina has been showing up with surprisingly regularity the past few weeks:  the Red-breasted Nuthatch. (Sitta canadensis) According to a recent news post by the Cornell Lab of Ornithology, Red-breasted Nuthatches and other northern species are heading south en masse searching for food due to a poor conifer seed crop in their normal wintering grounds across the Northern United States and southern Canada.  This species-wide southward movement in response to limited food is called an irruption.  Until about a month ago I'd only seen a Red-breasted Nuthatch once before -- in Yellowstone Park, Wyoming.  Now one visits my North Carolina backyard about every 30 minutes, digging another morsel of food from the suet feeder.

Red-breasted Nuthatch eating suet, November 19 2012

A Red-Breasted Nuthatch high above in a Longleaf Pine tree, the first-ever look at this bird in my backyard!

At least one other bird I'd never seen locally is also showing up with some measure of regularity -- the Dark-eyed Junco.  Now I realize for probably four-fifths of the bird watchers in North America the Dark-eyed Junco is one of the most common winter birds seen.  However in the five years I've been watching birds in my backyard one had never shown up until now.  The Juncos act a lot like White-throated Sparrows, seldom flying but instead walking across the backyard from brush or nearby bushes to feed on sunflower seeds dropped on the ground.  Their handsome gray and white coloring is a real treat to see!

The first time I saw a Dark-eyed Junco in my backyard.  He's on top of my shed peering down at the feeders below.

He brought a friend!  Two Dark-eyed Juncos are gleaning sunflower seeds off the ground near the feeders.

American Goldfinch

A bird whose numbers really varies from winter to winter here is the American Goldfinch.  Some winters they are THE most numerous bird I see.  I still remember a day in January 2011 when two-dozen of them were clustered on and near the feeders at one time.  Other times like last year (the 2011-2012 winter) we hardly had any at all.

On the chart below you can see the annual frequency of occurrence of American Goldfinches in six counties that make up the Cape Fear coastal region of North Carolina.  It's easy to immediately notice American Goldfinches are almost exclusively a winter species here, arriving in November and December and departing in April.  Within this typical seasonality another variation is apparent:  the 2011-2012 winter had very few American Goldfinches present in this six-county region with only 10-20 percent of eBird checklists including the species.  This current winter (2012-2013) American Goldfinch numbers are up and as of the data cutoff on this chart (November 20, 2012) there are more Goldfinches here than in any of the previous several years.

eBird graphical output showing the frequency of American Goldfinches in North Carolina's Cape Fear
Region from 2010 through November 2012.

Another pleasant surprise this Fall has been the sheer number of bird species I can observe in my backyard.  In a typical 30-60 minute sitting it's not unusual to see 20 species, up from a typical 12-15 species this same time last year.  Part of this increase might be I'm becoming a more-proficient bird watcher with time, but most of it I'm sure is there are simply more bird species visiting here.  On this morning's checklist I observed 24 species, annotated below from Cornell University's eBird website:

1	Red-tailed Hawk being harassed by a very coordinated flock of ~50 Starlings
8	Mourning Dove
1	Downy Woodpecker Age & Sex Juvenile Immature Adult Age Unknown Male Female 1 Sex Unknown
1	Blue Jay heard only
1	American Crow
4	Fish Crow
3	Carolina Chickadee
2	Tufted Titmouse
1	Red-breasted Nuthatch
1	Carolina Wren
115	American Robin
2	Northern Mockingbird
1	Brown Thrasher
325	European Starling ~200 in this picture; an additional ~125 in nearby trees
1	Yellow-rumped Warbler (Myrtle)
2	Chipping Sparrow
1	Song Sparrow
1	White-throated Sparrow
2	Northern Cardinal Age & Sex Juvenile Immature Adult Age Unknown Male 1 Female 1 Sex Unknown
7	Red-winged Blackbird
17	Common Grackle
7	House Finch Age & Sex Juvenile Immature Adult Age Unknown Male 3 Female 4 Sex Unknown
2	American Goldfinch
5	House Sparrow Age & Sex Juvenile Immature Adult Age Unknown Male 2 Female 3 Sex Unknown

Backyard Citrus Harvest

Here on November 16th I'm almost through my fall citrus harvest.  This year has given me the best citrus season I've had yet.  The reason is two-fold:  my trees, planted in 2009, are finally getting large enough to bear significant amounts of fruit; and last winter was quite mild with no spring freezes or excessively cold winter temperatures.

A Changsha Mandarin cut open to reveal the juicy interior and large number of seeds

Changsha Mandarins in late October

Changsha Mandarins are too seedy to eat off the tree so we used these for making "orange" juice.  If you've never had juice from Changshas, expect a much stronger flavor with a more of an orange-reddish color than what you'll typically find from grocery store orange juice.  It takes a fair number of these mandarins to make a glass of juice (at least ten) but the end result is definitely worth it.  Changsha Mandarins look amazing cut open, and the smell is slightly more intense than your typical Valencia or Navel orange from the grocery store.  Changshas are cold hardy -- our lowest temperature last winter was only 20 degrees and even the completely exposed Changsha Mandarin branches I didn't cover had no visible damage.

Admiring a glass of freshly-squeezed Changsha Mandarin juice

My son helping pick Owari Satsumas

Two closely-related varieties of Satsumas both yielded fruit for me this year:  Brown's Select and Owari Satsumas.  The Brown's Select Satsumas ripens about 10 days ahead of the Owaris, but both have a similar sweet orange taste and share the same outside appearance and internal structure of any of the sweet citrus varieties.  While about half of my Satsumas were seedless this year, none had more than 4 or 5 seeds per fruit -- not too bad!  If you're just getting started in growing citrus in your non-tropical backyard please select at least one variety of Satsuma to begin with.  They're similar enough to sweet oranges to satisfy your expectations in taste, shape and color, plus they're cold-hardy and easy to grow.

Owari Satsumas are exceedingly easy to peel, even for a four-year old child. 

Yuzus in my backyard, ready to pick at the end of October

And lastly, the Yuzu tree really had a banner year for me.  Bright yellow in color and with a fragrant taste of about 80% lemon, 10% lime, and 10% something else I might loosely describe as pine, each fruit yielded about an ounce of juice.  With the incomparable culinary skills of my wife put to use, we've enjoyed Yuzu bars made in the same manner as traditional lemon bars, Yuzu pie made like Key Lime Pie, and even delectable Yuzu ice cream.

I want to focus on the Yuzu ice cream since it's probably the best vehicle for experiencing the true taste of Yuzus alone.  When I first suggested trying to make Yuzu ice cream I didn't know if it was even possible -- doesn't acidic citrus juice curdle milk upon contact?  My wife found a recipe online that gets around that potential problem and made excellent-tasting ice cream.  She adapted her recipe from a Lemon Gelato recipe found at this link from tasteofhome.com.

Recipe for Yuzu Ice Cream

1 cup milk
1 cup sugar
5 egg yolks, lightly beaten
3 tablespoons grated Yuzu peel
3/4 cup Yuzu juice
2 cups heavy whipping cream


In a small heavy saucepan, heat milk to 175°; stir in sugar until dissolved. Whisk a small amount of hot mixture into egg yolks. Return all to the pan, whisking constantly. Add Yuzu peel. Cook and stir over low heat until mixture reaches at least 160° and coats the back of a metal spoon.

Remove from the heat; strain. Stir in Yuzu juice. Cool quickly by placing pan in a bowl of ice water; stir for 2 minutes. Stir in cream. Cover and refrigerate for several hours or overnight.

Fill cylinder of ice cream freezer two-thirds full; freeze according to manufacturer's directions. Transfer to a freezer container; freeze for 2-4 hours before serving. Yield: 1-1/2 quarts.


Give it a try, you'll like it!

I've got several other citrus trees in my backyard that are still a little too young to bear fruit.  They've all put on several additional feet of vegetative growth this year so I'm hopeful I'll be able to expand this list and add several new fruit experiences to this blog next year:  Ichang Lemons, Sanbokan Grapefruit, Ambersweet Oranges, Croxton Grapefruit and Ten-Degree Tangerine.