Sunday, September 28, 2008

Overwintering Tender Plants, Part III

Variegated Flowering Maple overwintered last year

Okay, so you've decided to overwinter, and maybe even propagate some of your tender plants inside. You've found a good spot to keep your plants, and have a good source of natural or artificial light. You've decided which plants to bring in, and have the supplies you need on hand which may include a quality potting mix, water-tight saucers or trays, nursery pots in various sizes (or more decorative containers if you prefer,) safe insect controls, sharp pruners, Ziploc bags (or more economical generic zip-type bags,) maybe some rooting hormone, and a watering can or hose*. If you don't have nursery pots, clean deli, yogurt, cottage cheese, or other plastic containers will work just fine as long as you make some drain holes in the bottoms. Save the lids and they can be used as saucers! Persian Shield, overwintered last year

Individual specimens can be brought inside in the same container they were in while outside. With mixed containers, you'll need to decide whether to bring in the whole thing, or just select individual plants. You could also opt to take only cuttings of certain plants rather than bringing the entire plant indoors. Coleus and Iresine are good candidates and examples. If you opt to break down the container and bring in only certain plants, and cuttings of others, this is where the extra nursery pots or other containers come in, and they can also be used for propagating later, after your plants are already inside. If you're transferring a plant into a new pot, be sure to choose one that allows room for some root growth while not being too big. An extra inch or two larger than the root ball is probably about right. Too small and the plant will get rootbound, too large and it may rot.

For starting cuttings, choose containers with room for root growth, but not too big. I start cuttings in 4" square or 4 1/2" round nursery pots. Some things will be fine over the winter in their starter pots, others may need to be bumped up to something larger over the winter. Watch for roots beginning to come out the bottom of the container before moving to a larger one. I bump up incrementally - from a 4 1/2" to a 6" for example, later to a gallon if necessary. Making too big a jump in pot size can be an invitation to rot, fungus, and bugs.

Coleus started from a cutting

You can opt to leave blooms and buds on your plants when you bring them in. I find it's less trouble to remove the blooms and buds before bringing plants indoors. Except plants I plan to propagate, I cut most plants back before bringing them inside, removing buds and blooms, and any yellowing, dead, or damaged foliage. I clean the soil surface of any debris. Cutting them back reduces watering, encourages fuller branching, and prevents plants from getting overgrown, spindly, or sprawling during the shorter, darker days of winter. Good hygiene will help keep your overwintering plants healthy.New Dragon Wing Begonia will be overwintered this year.

Propagating tender plants from cuttings is a fun, cheap winter pastime, easier with some plants, more challenging with others. Coleus, brugmansia, datura, all varieties of impatiens, heliotropes, iresine, some begonias, fuchsias, and sweet potato vines are all examples of plants easy to start in ordinary potting mix, or even water in the case of some of these. Don't be afraid to experiment - it's a fun learning experience. Sweet potato vines can easily be started by cutting and replanting pieces of the tubers - just make sure each piece has at least one eye. Iresine started from a cutting

To start new plants from cuttings, choose healthy stems 3-5 inches long with several leaf nodes. Begin by filling your pots with a good-quality soilless (sterile) potting mix. Water the mix and allow it to drain. Make a clean diagonal cut at the base of the stem. The diagonal increases the surface area of the cut and allows better uptake of water while the roots are forming, increasing your success rate. Snap off or cut the foliage away from the bottom two or three nodes. Cutting larger leaves in half will often reduce wilting of the foliage before roots begin forming.

Rooting hormone accelerates the rooting process and increases rooting success rates. If you opt to use it, first wet the stem up to the top stripped leaf node, then coat that part of the stem with rooting hormone. Next, use a pencil, bamboo stake, or even a screwdriver to make a hole in the potting mix deep enough to insert the cutting so soil covers the topmost stripped leaf node. Insert the cutting, making sure the stripped nodes are below soil level. Gently water, making sure the soil makes good contact with the stem of your cutting. Remove or trim any foliage making direct soil contact. Place your cuttings in a warm area out of direct artificial light or sunlight, and keep the soil evenly moist. Brugmansia started from a cutting last winter is 4' tall. Notice the buds?

Some wilting of your cuttings may occur. Watch them carefully the first several days. Misting several times a day will help keep the foliage hydrated as the cutting is forming roots. If your cutting is wilting, easier than misting is making a mini-greenhouse for it by zipping an appropriately-sized Ziploc bag tightly around the rim of the pot. A little fresh air is fine, but after a few hours you should see some condensation on the inside of the bag. If not either your cutting needs a bit more watering, or your bag needs to be sealed a little tighter. A gallon-size bag seems to work best for me. In most cases they're big enough to allow breathing space for the foliage. The bags can be reused many times. A bamboo stake or two, broken or cut to an appropriate size and inserted in the perimeter of the pot will keep the plastic from direct contact with the foliage, keeping it healthier. The humidity inside the bag will help keep the foliage hydrated during the rooting process, increasing your success rate, and speed the rooting process.

You probably won't have to water the cutting at all while the bag is in place. After a couple of weeks, you can check for root development by giving a very gentle pull to your cutting. If you encounter resistance, your cutting is probably already rooting. Once the roots begin to form the bag can be removed. As the cutting grows, you can pinch it to encourage fuller branching if you wish. Re-pot it into a slightly larger container if the roots start coming through the drain holes before it's time to plant it outside.

In the spring, after the danger of frost is past, you can begin moving your plants back outside. They'll need to be hardened off for a few days in a shady, sheltered spot before planting them in their new summer home. You can start this process a bit earlier by putting them outside during the day and bringing them back in if the temps dip too low. (That's too much work for me - I'd rather wait until the weather's a bit more settled. Once they're back outside, I want to be done schlepping them!)

Because they're used to being sheltered indoors, high winds, direct sunlight, or temperatures below 45-50 degrees could spell disaster without an adequate hardening off period, so be patient and take your time with this step. I learned that the hard way with a variegated begonia hanging basket and several Diamond Frost euphorbias I overwintered last year. I put them outside on a day that turned out to be chillier and windier than I'd expected. By the time I got home from work that day, these poor plants that I'd tended all winter had been mercilessly whipped by the wind and were virtually defoliated. They did recover quickly and have been beautiful all summer, but they looked pretty awful their first couple of weeks outside. My husband kept offering to buy new baskets from the nursery, they looked so pathetic. I was confident they'd recover with a little patience and TLC, and they did. The variegated begonia, recovered

Rose, I hope these posts helped motivate you to try overwintering a few tender plants inside this winter, and maybe even encouraged you to try starting a new plant or two from cuttings! I hope I didn't make it sound too complicated - it's really very easy, fun, and a satisfying way to stretch your gardening budget!

Any and all suggestions for starting plants from cuttings or overwintering tender plants are very welcome - I'm pretty new at this, and still have plenty to learn!

*In an unfinished basement with a concrete floor, a hose can be connected to the utility sink faucet, making watering less of a chore if you're overwintering a lot of plants. Water carefully to avoid splashing and puddling. Wet conditions may encourage bugs.


  1. What an informative post-and timely too! I did not know to winter over heliotrope from cuttings so I will be getting a few today. Thanks! Love that variegated brugmansia.

  2. Anonymous11:51 AM

    Your Persian Shield is gorgeous -- another new plant to me! Everything looks like it certainly overwintered very well.

  3. Anonymous2:49 PM

    I love your Persian Shield too. It's a shade plant, right? Great post today on overwintering & cuttings. I don't plant any tender perennials or very many annuals so I don't normally bring anything in for the winter. But great advice for the future!

  4. Thanks for reminding me to take some cuttings from my coleus and brugsmania! I love both plants. The Brugsmania usually winters over but I would like to give my daughters a plant. I love my coleus this year and want them in my garden next too! Thanks again for the reminder!

  5. I just read your overwintering series, GardenGirl, and this clear and useful information should be bookmarked by those with basements and windows to keep plants. Your set-up under lights in the basement looks wonderful.

    Down here I move plumeria and citrus into the garage and put the Thanksgiving cactus in the only good window, but we don't have basements. So far the Persian Shield has made it through 2 winters in the ground.

    Annie at the Transplantable Rose

  6. Okay, Linda, I am so impressed with all your tenacity first of all and then with all your careful & detailed information. Funny how your garden has so many of the same plants I do... which is actually quite exciting for me to see. Not typical for a northern garden... but then again you keep telling me how much you love the tropicals.

    Interestingly, I've been doing some of what you explained the past several weeks ... only outdoors. Getting ready for some late fall plantings I've been rooting cuttings of coleus, blood leaf (Iresine), persian shield, dragon wing/angel wing begonia, draceana, and salvia coccinea. I'm really lazy though. If I can't just stick it in a pot of soil and water it daily until it takes hold I don't mess with it. I'm also digging up off-shoots from my snow bush, shell ginger, and plumbago plants -- transferring them to pots to plant either late autumn or late winter. It really helps for multiplying so many plants.

    Your angel wing begonia is very pretty as is all the coleus I spotted in various photos... I like the first photo of the maple too. Can you believe I don't have a single Brugmansia? I might be the only person in Florida without one.

    Great post, Linda. I read through it just to try to understand all the trouble you northern folks have to go through to have your beautiful gardens come spring. :-)
    Meems @Hoe&Shovel

  7. Thanks Tina! Heliotropes are easy to root and do well inside. I'm going to bring in the mama plant - I just moved it to a larger container since it's outgrown the old one.

    Thanks Nancy! that one's pretty easy to start from cuttings.

    I was pleased with the results of overwintering so many plants. They overwintered well, saving them felt so much less wasteful, (plus I kinda get attached to them,) and I saved a bunch of money.

    Hi Racquel, yep, they like shade. They do fine with some morning sun too. I never used to do tropicals or other tender plants until the last few years. Now I'm kind of hooked on them!

    Hi Sherri, you're welcome! You're so lucky to be able to overwinter the brugmansia outside. They're the heaviest plants to bring in, and they take a lot of space!

    Hi Annie, that's cool your Persian shield overwinters outside for you!

    I'd like to try putting some plants in the garage. I'm not sure how cold it gets. It's attached, so I'm guessing it might be ok. Just to be safe, first I might put a thermometer in the garage this winter and keep an eye on how cold it gets, then decide.

  8. Hi Meems! Thanks! I hate to just let them die! So many people come into the nursery and buy all those beautiful tropical plants, then leave them to freeze to death and start all over again the next year.

    I do love the tropicals. I kind of get attached to them, enjoy taking care of them and propagating them over the winter.

    I'll be getting my gardening fix tending my little basement garden, while you're enjoying your tropical 'winter' garden outdoors!

  9. Thank you again, Linda, for all this valuable info! On my to-do list this week is cleaning up a corner of the basement and getting the garage cleaned so I have space for all these cuttings. I knew I could take cuttings of coleus and the sweet potato vines, but you've given me ideas for so many more plants I'm going to try. My basement may look like a greenhouse when I get done!
    By the way, I use Persian shield--one of my favorite accent plants--in containers in the sun, and it always does well. It's a pretty tough plant.

  10. I am amazed! Thank you for all this good information. I had no idea I could work with all these plants. I've noticed the Persian Shield before, but haven't purchased it... yet. ;-)

    I'm definitely going to bookmark this post! Thanks again.

  11. Hi Rose, you're welcome! I'm glad you found it helpful, and wish you great success in overwintering some of your plants indoors. It's good to know Persian shield is so versatile!

    Hi Shady, I'm glad you found this series of posts helpful. I think you'd like Persian shield. It's a beautiful foliage plant, does great in the shade, is easy to overwinter, and is easy to start from cuttings.

  12. Wow, you're amazing! Thank you for sharing Linda, I overwinter a few tropical plants but will try some of my other ones this year, just in time too! :)

  13. Hey Kathi, aw shucks, thank you! I'm glad you found these posts helpful!

  14. Thanks for this great, informative series! For the 1st time I'm going to be overwintering a large Pelargonium & trying to overwinter a Coleus cutting & a Sweet Potato Vine. I figure all I have to lose is time & potting soil.

  15. Hi MMD, I'm glad you enjoyed it! Have fun playing with your plants. You picked some nice, sturdy plants to overwinter indoors.


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