You are currently viewing “Annuals” You Can Overwinter!

By Linda Peacock, Master Gardener, SCMG

It is that time – frost is coming or at least has come to my house.  But what a year!  Many annual baskets and planters still look great, and it is well into Autumn!  This means it can change fast, so we need to be prepared.  Take a look.  Which plants need to be brought in to use again next year?  Many annual plants can be enjoyed year after year if we take a little time just before (or after) the frost comes.  It is a great way to save a little money while we cheer up the wintery days with some indoor greenery!

Some can be brought in as houseplants.  Many are tubers and corms and should be stored properly.  Most of those need to be “cured” which allows their outer layer to dry enough to protect it by holding in enough moisture to get it through the winter.  In the spring discard any shrivelled up or ones with any moldy or wet mushy spots.  Sometimes it takes a few tries to find the best spot to store them but once you do it is such an easy way to keep these plants for many years.  I live in zone 5b west of Barrie, Ontario and my best spot for tubers and corms is in a little room we use as a cold cellar in the crawl space under our house.  The temperature seems the best for many varieties.  Some do need it colder than others, but you can adjust that easily by using different storing mediums or locations within the room itself.  One wall of this cellar shares a wall with an unheated garage, this gives me a colder area for things like the Cannas.  The most important thing is to make sure they don’t get too moist or freeze.  One of my favourite storing mediums is shredded paper which I can reuse as mulch around my vegetables and herbs in the summer.

Before we go any further take the time to label everything.  You think you will remember which is which but believe me you will not.  Everything looks very different when they are dried out – even the leaves can be indistinguishable.  Now if you don’t care which colour goes where next year this may not matter to you, but usually this is something that people want to know.

Gladiola  Gladiolus oppositiflorus

These little guys have very tough foliage, wait until they are yellowed or dying back or when the first frost comes then pull them out.  Cut the stems back to 1” and let them dry out for at least a week until the corms are completely dry and all dirt is removed.  I store these in a box or basket of shredded paper, it seems to work the best for my conditions.  They are kept in the cold cellar in my crawl space.  They can be left there until it is time to plant them outside (when there is no more frost in the forecast). Remember that Gladiola can be picky they don’t always like being planted in the same place each year.

Tuberous Begonia Begonia x tuberhybrida

Remove the entire plant from the soil just after the first frost, I tend to pull them out just before then in our climate because they are very tender.  Cut off most of the foliage and remove as much soil from the tuber to allow it to dry properly.  I keep mine in our unheated, covered porch for about 2 weeks or until any stems come away easily. Carefully remove any remaining soil and pack each tuber away in a paper bag and store in a cool spot that will not go below 10°C.  I keep them in the cold cellar in my crawl space under the house.  In early April I bring them out and plant them in shallow pots with the top of the tuber just below the surface of the soil.  Keep evenly moist, not too wet and they will sprout in no time.

Calla Lily Zantedeschia aethiopico   Canna Lilly Canna x generalis

These can be pulled out when the foliage starts to yellow or just before the first frost.  Cut stems down to about 3” and let the rhizomes dry out well just like the Tuberous Begonias.  These do better when stored in vermiculite or sand.  The Callas should be stored about 10°C, however, the Cannas should be a bit cooler down as low as 5°C.  In the spring pot them up.  Cannas should have the whole clump planted together.  If you divide the rhizome clump make sure each new clump has a piece of stem attached, the buds are located at the very base of the old stems.

Dahlia Dahlia bipinnata

These beauties are best left in the ground until at least 2-3 days after the first frost.  They need to develop the “eyes” that will produce the shoots for next year’s plants.  Remove as much dirt as you can and let these tubers dry out for at least 1 week.  I used to keep these in vermiculite but had some failures, since then I have used perlite that allows less moisture to collect. A box of tightly packed shredded paper works great as well.  In early April I plant them in good sized pots (they don’t love being transplanted so I leave that until they go into their final spot in the garden).  They need to be planted with the top of the tubers very close to the top of the soil.   Some of the tubers may already be sprouting, those barely need to be covered at all.  Keep them moist but not wet and they will sprout in a few weeks.

Annual Geranium Pelargonium

This is the easiest of all!  I bring any planters containing geraniums into our covered, unheated porch when frost is imminent.  Remove any other annual plants (or weeds) that may be in the soil.  I do not water them after this point.  They are very hardy plants and keep blooming for weeks after I bring them in. I enjoy them for as long as I can, but the day eventually comes when I need to clean them up and put them away.  I cut back any blooms or spent foliage.  If there are long stems with foliage on them, I cut them back as well.  I keep the remaining foliage as is and I put the whole pot downstairs.  These do not go into the cold cellar; they go on tables up against the crawl space windows.  They stay here until early April.  I don’t water or look at them.  In the spring when I go downstairs to retrieve my tubers, I also bring these geranium pots upstairs.  Lots of years they have already produced new bright green foliage, even small blooms. I place these by a bright window and start watering.  I do not do anything with the soil until it is time to plant them into the garden or planters.  As they are growing their new stems I cut many off to create new plants.  I set the stems in water until roots form, and they are planted into new fresh soil.  This trims back the main plant and keeps it compact while promoting new, fuller growth.  At the end of May when no threat of frost remains these plants are ready to move outside, most of them are starting to produce buds.  The main plants can be repotted or if leaving in the original container I amend the soil, it does not need to be completely replaced.

Coleus Coleus scutellarioides

These plants are very tender and need to be protected from frost.  If you have a spectacular one that you would like to use again, bring it in as a houseplant.  Check the soil for weeds and bugs first.  The safest method to bring in as a houseplant is to completely remove from soil, wash roots and repot.  They need direct sunlight.  Even with lots of light they will get very leggy, however, in the early spring just snip long shoots off and root in water to create even more beautiful plants.  Even if you do not want more than one of them, trim the main plant back to promote fresh, fuller foliage.  A few herbs can be treated the same way, parsley, oregano, chives, thyme, basil and sage.  Some herbs (such as rosemary and tarragon) do not like the conditions inside during winter and they don’t always thrive.

Houseplants That Were Outside

I usually put my orchids and houseplants outside to decorate the covered porch and patio.  When they are first put outside they need to be climatized slowly or they may discolor, but they usually recover very quickly if they do.  They thrive in the brighter light and consistent rain of the summer.  It gives them so much strength to decorate your home for the winter.  The orchids really thrive!  I leave them in the covered porch to keep them out of bright light and put them outside on rainy days.  They love to be drenched and then dry out.  This promotes blooms on plants that do not always bloom if they stay inside all year.

Take a quick look, dig up some tubers (label them) and start them drying out.  Bring in a few pots of geraniums (label them too).  It does not take long, and the rewards next year are amazing!