Green Thumb Tip #13: Breaching Your Zone

It is time to save our favorite Alocasia before our first freeze of the season, tonight.


We expect frost tonight, the first of the season.   In fact, the forecast suggests that we may have temperatures in the 20s overnight; the result of an approaching cold front and gusty winds from the north all day.

We can’t complain.  Here in Zone 7, we know that frost is possible any time from October 15 on.  We’ve escaped the inevitable for nearly an extra month, and tonight is the night.


Alocosia ‘Stingray’ in August, with Begonia ‘Griffin’ behind.  Both came inside today for the winter.


Bringing tender plants in for winter remains one of our annual rituals here in our forest garden.   We procrastinate as long as possible, to give the plants every day possible out in the air and sunshine.   We’ve found that even tender tropicals will survive a few nights in the 40s better than a few days in the garage, and so have learned to wait until we are sure that we have a freeze warning before we gather them back indoors.  Moving them back and forth several times over our long fall really isn’t practical; we wait for the last possible moment to commit.


Colocasia ‘Mohito’ is marginally hardy in our area. I couldn’t lift this pot, but brought all of the divisions of the plant indoors today.


Preparations for the ‘great migration’ included doing a little homework to refresh my memory about the lowest temperatures some of our plants can tolerate, before they turn to mush.  Nearly all of our Begonias won’t tolerate any freezing at all.  The hardy ones are mostly dormant, already.

But the Aroids, the Alocasias and Colocasias, have different degrees of cold tolerance.  Unlike Caladiums, which like to stay cozy at 50F or above, some Colocasias remain hardy to Zone 6.


Colocasia ‘Pink China’ has proven hardy in our garden. It spreads a little more each year and grows lush and reliable from May until November. I expect to find this whole stand knocked down by frost when we come out tomorrow morning.


When we talk about  USDA agricultural zones, there are three variables in play; all very important for which plants you may grow.  First, dates of first and last frost are pretty standard across a given Zone.  For example, here in Zone 7, we expect our first frost around October 15, and our last freeze around April 15.  That gives us a solid six months of outdoor growing season, which means we can raise lots of different sorts of crops in our zone.  There is sufficient time for a plant to develop, bloom, and ripen fruit.  A few miles to the southeast, nearer the Atlantic, Zone 8 begins.  Zone 8 has later first frosts (November 15) and earlier last frosts (March 15).


Colocasia have runners, and each runner will create a new little plant. These special stems run just at ground level. This is how a dense stand develops from a single plant. Were you to visit my garden, I’d offer you as many of these little Colocasia plants as you would take!


So knowing your Zone (updated in 2012,) not only tells you how many weeks of the year you have a 50% chance or greater of having freezing temperatures, at least overnight; it also tells you how cold those temperatures may go.   Here in Zone 7b, we may experience a low between 5F-10F.  Most winters we never drop below the teens, here, but it is possible.  Zone 8 may have temperatures down to 10F, but Zone 9 wouldn’t expect temperatures to drop below 20F.

Knowing this helps me make choices about what to bring inside, where  to keep overwintering plants, and what to take a chance on leaving outside until spring.  When space is limited, hard choices must be made if one wants to share the house with the plants for the next six months!


Colocasia ‘Tea Cups’ is hardy to Zone 7b. I still brought many of these plants in to hedge my bets, since we are right on the edge….


If a plant is hardy to Zone 8, we sometimes have success keeping it outdoors when we provide mulch or significant shelter.  In a mild winter, we may not dip below 10F to begin with.   Plants with deep roots may be mulched, or may have a little shelter built around it with most anything that will trap and hold heat on those few cold nights.  Our patio is a great place to offer potted plants shelter through the winter.  It offers shelter from the wind, and also absorbs and holds a bit of heat on sunny days.



A plant rated to Zone 9 or 10 will definitely need to come indoors in our area.  But because Aroids have a dormant period over winter, we can keep them in our low light but frost free basement.

As Colocasias and Alocasias grow more popular, enthusiasts are left deciding whether to try to save them for another season, or whether to start next season with fresh plants.   Sometimes space determines our choices, other times our budget.  That said, I’ve found four ways to keep these beautiful plants from one season to the next.


Colocasia ‘Black Magic’ is hardy to Zone 8. We were fortunate to have one overwinter in a protected area, and this is an off-set I dug up in August to grow on. It is now safely tucked into our garage for the winter.


I found two of our most spectacular Alocasias back in February, at Trader Joe’s.  They were right inside the door, with a few other pots of ‘tropical’ plants.  Because I recognized their leaf, I bought two, intending to use them in large pots to frame our front door all summer.  What came home in a 4″ pot, grew over summer into a huge and beautiful plant.  I learned today that their roots had completely filled the 20″ pots they have grown in since early May.


This Alocasia, originally from Trader Joe’s, wasn’t labeled when I bought it last winter. It reminds me of A. ‘Regal Shields,’ but grows a bit larger.


I can barely slide those pots when they are well-watered.  And, I plan to re-plant them for winter interest.  There was no question of trying to move them into our home or garage to overwinter the plants.

But last night I did my homework, and spent a while searching out how others have managed to overwinter large Alocasias.  Since the plant goes dormant, it can be kept, barely moist, out of its pot in a frost free basement or garage.    So I pried each of my beautiful Alocasias  out of their pots this morning, and lowered each, root ball intact, into a large paper grocery bag.  I’ve set the bags into shallow plastic storage boxes in our basement.  The leaves will wither; the soil will dry.  But life will remain in the plant, and I can pot it up again in spring for it to continue growing.


How many plants? I didn’t count…. But here are four grocery bags filled with Aroids to sleep through winter in the basement.


I decided to hedge my bets again this winter by storing our Aroids in a variety of ways.  While I’ve brought a few indoors in smaller pots to either keep growing in our living room, or slowly go dormant in our garage or basement; a great many got yanked from their pots this morning and stuffed into grocery bags.  Now the Alocasias will mingle for the next few months with A. ‘Stingray,’ C. ‘Mohito’, and C. ‘Tea Cups.’

C. ‘Tea Cups’ is supposed to be hardy in Zone 7.  Actually, we had one overwinter in a very large pot last year, but it was slow to emerge and never grew with much vigor over summer.  So again, I hedged my bets.


A. ‘Stingray’ came home in a 4′ pot this spring. It has grown prodigiously, and there were several small off-sets. I pried these out of the wet soil, and am storing them in the grocery bags for winter.


Remember, all of these plants create off-sets.  So, I left a few plants growing in the circular bed we began in spring.  But I pulled up enough to replant the bed next spring, if those don’t survive winter for whatever reason.  I have a few C. ‘Tea Cups’ overwintering in moist soil in pots, and others set to go dormant in paper grocery bags.

The very small divisions of Colocasia ‘Black Magic’ that I potted up in late summer came in to the living area in their pots, along with  A. ‘Sarian’ and a few A. ‘Amazonica‘.   I can give them window-sill space and keep them growing.  Even if you don’t have space to keep the largest of your Aroids, chances are good that there will be a small off-set that you can save over winter.



For plants like Begonias and Brugmansias, which don’t create off-sets, consider taking cuttings if you need to conserve space. If you don’t have room for the whole pot or basket, cut a few vigorous branches to root in a vase or jar near a window.

Cuttings placed in water now will root, and may be potted up in early spring.  I always have Begonia cuttings rooting in vases of water, but I brought a few more cuttings in today.  We just have too many pots of Begonias to save them all.  But I am careful to save some of each variety.  Because plants like Begonias root so easily in water,  once you have a variety, you can keep it going indefinitely.



Many, many plants will root in water.  I’ve experimented over the years with keeping many genus of plants going, because the nursery trade just isn’t that dependable when there is a particular variety you want to buy in spring.   Maybe you’ll find it, but maybe its shelf space will be given over to something newer or more fashionable, and your favored cultivar just won’t be available in your area.

My friends know that even if I had a good sized greenhouse, I’d soon fill it to the rafters like some botanical Noah’s Ark.  As it is, our living space is filled, once again, with my coterie of plants.  My partner is blessedly patient with my horticultural obsessions.


Begonia ‘Richmondensis’ is an angel wing Begonia which performs well in a hanging basket.  A perennial in Zone 10,  you can overwinter it in its pot, or as a cutting.


There is no shame in letting ‘annuals’ perish when winter finally blows into your garden.  But your Zone doesn’t have to limit what you can grow, and winter doesn’t have to destroy your beautiful collection of plants.

Master a few handy hacks, and you can keep your favorite warm-weather plants growing (and multiplying) indefinitely.


A. ‘Amazonica’, also known as ‘African Mask’, grows vigorously in a large pot. I’ve kept this pot going for several years by letting it over winter in our living room..

Woodland Gnome 2017
“Green Thumb” Tips: 
Many visitors to Forest Garden are amazing gardeners with years of experience to share.  Others are just getting started, and are looking for a few ‘tips and tricks’ to help grow the garden of their dreams.

I believe the only difference between a “Green Thumb” and a “Brown Thumb” is a little bit of know-how and a lot of passion for our plants.

If you feel inclined to share a little bit of what YOU KNOW from your years of gardening experience, please create a new post titled: “Green Thumb” Tip: (topic) and include a link back to this page.  I will update this page with a clear link back to your post in a listing by topic, so others can find your post, and will include the link in all future “Green Thumb” Tip posts.

Let’s work together to build an online resource of helpful tips for all of those who are passionate about plants, and who would like to learn more about how to grow them well.

‘Green Thumb’ Tip #1:  Pinch!

‘Green Thumb’ Tip #2:  Feed!

‘Green Thumb’ Tip #3 Deadhead!

‘Green Thumb’ Tip #4 Get the Light Right!

‘Green Thumb’ Tip #5: Keep Planting!

‘Green Thumb’ Tip #6: Size Matters!

‘Green Thumb’ Tip # 7:  Experiment!

‘Green Thumb’ Tip #8  Observe

‘Green Thumb’ Tip #9 Plan Ahead

Green Thumb Tip # 10 Understand the Rhythm

Green Thumb Tip # 11:  The Perennial Philosophy

Green Thumb Tip #12: Grow More of That! 

‘Green Thumb’ Tip:  Release Those Pot-Bound Roots! from Peggy, of Oak Trees Studios


About woodlandgnome

Lifelong teacher and gardener.

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