For Plants in Pots and Other Tender Stuff!
Question. Hi, Mike: I love your show;great advice! Now, I need some on how to winter over the two datura plants I purchased this spring. They're perennials, I'm told, and doing fine right now, but I hear they die in winter if left outside. Whatshould I do? I travel a lot during winter and can't tend them properly as houseplants. Can I dig them up, pot them up & put them in the basement? If so, do I not water them at all until spring?
They produce seed from prickly balls,which burst open when dry. If I gather the seed in the burst pods, will they produce new plants if I plant the seed in spring? Do I need to put that seed in the refrigerator in a plastic bag in peat, or what? Thanks for any help.
- ---Judy from Princeton, NJ
Answer. Hey—thank YOU, Judy; this isthe perfect time of year to talk about plants that are too tender toleave outside for the winter.
But first, a warning. Your daturas (scientific name Brugmansia) are great plants. They can grow in very wet areas and their beautiful tubular flowers deliciously scent the night air. But those flowers (and every other part of the plant) are so poisonous you'd likely hear it sother common name— Angel's Trumpet—if you chowed down on a flower or a leaf. Daturas should not be grown anywhere near children or food plants(a little sap or nectar dripped onto a strawberry below could make your eally sick) and you should always wear gloves when handling them.
OK? Now, if you were one of our Southern listeners, you wouldn't have to do anything. But you have heard correctly—in your Zone 6 garden,this semi-tropical plant (and many other garden favorites planted by unsuspecting growers) will perish overwinter. You could dig it up and pot it up IF you were willing to keep it going as a houseplant overwinter. But most people don't bother; they simply treat it as an annual flower—which would be especially easy for you, cause you're already planning on saving the seeds.
To do that, let those pods dry as brittle as can be, and then harvest them at the end of a nice, long dry spell. Let them dry some more indoors and then seal the dry seeds up in a glass jar with some of those silica gel packets you get in vitamin bottles and keep it in acool, dry, dark place. (NOT the fridge; too damp!) This basic advice applies to almost all saved seeds, except tomatoes, which are special.Anyway, datura seeds don't need the cold treatment you're describing,but a very nice site, http://www.brugmansias.org,warns that they are covered by a corky coating. So before you start them next Spring, soak the seeds in water for 24 hours and that stuff should come off.
OK; general rules for tender plants.Woody, shrubby things too tropical to survive your winters—like citrus and bay leaf trees—should really be grown in pots. No plant enjoys being transplanted a couple of times a year, and planting in pots will also keep them smaller, making them more manageable when you have to bring them in for the winter.
If you're going to pot up ANY plant currently in the ground for winter salvation, get started NOW. In the evening, make a big circle around the plant with a sharp shovel, lift it out of the ground, pot it up keeping as much of the root ball intact as possible, water it well and then leave it outside (NOT in direct sun) for a few weeks to let it get over the shock. Then, before frost, choose one of the following three options:
- Wash the leaves really well several days in a row with sharp streams of water to get rid of any buggy wuggies and bring the plants indoors to a solarium or sunny windowsill. Depending on the plant, the amount of sun and your latitude, it might bloom and grow over winter, but more likely it will go kind of dormant. Either way,water it on the light side and give it no food other than some dilute
- compost tea (if you must); plants in winter don't need food and can't use much water. This is your only choice for things like bay leaf and citrus trees.Or
- Take the pots toa place that stays cool but above freezing—like a basement or attached garage—and hope that the plants simply go dormant instead of dying. (Think good thoughts; clap in you believe in fairies….) Do not feed these plants at all, and water them—lightly!—only two or three times all winter. Or
- Group them together against an outside wall of your house (preferably one that leaks heat, like a chimney) and bury them in shredded leaves, a good foot deep on all sides. NOT whole leaves—they would mat down and smother the plants. This trick works great with geraniums—but so does just about anything else.
- ANY plant in apot. If it drops below freezing where you live, you cannot leave potted plants outdoors. Arose or a dwarf apple tree, for instance, will survive even a frigid zone 4 winter in the ground nicely, but that same plant in a container will perish on the first bitterly cold night in zone 6 when its roots freeze. Your best bet for roses (which are darn finicky about not having their roots in the ground) and non-citrus fruit trees (which require a certain number of chilling hours to bear fruit) is huddled up against the house under a blanket of leaves. Or, if you have room inthe garden outside, just bury the pots in the ground before it freezes;this will insulate the roots nicely. Then just dig the pots up again come Spring. Most other potted plants should go into a sunny window or dormant down in the basement.
Summer blooming 'bulbs'. If your ground freezes hard in winter,you have to 'lift' tropical summer bloomers likedahlias, gladiolas,cannalilies, tuberousbegonias and the like. Get those VERY tender begonia tubers out of the ground early—long before frost. Leave the others in the ground till after the first frost blackens the above-ground growth, then pull the 'roots' out of the ground and cutoff the above-ground stuff. Then pack those tubers, rhizomes, bulbs,etc. in slightly damp peat moss and/or vermiculite and store them in a cool spot that won't freeze—40 to 45 degrees is ideal. Or better still,pot them up and grow them as houseplants till next Spring! You might get some flowers, but you'll certainly have HUGE leafy plants to putout next year that will bloom a good month earlier than planted tubers.If you only get a few light frosts in your region—or you live in the middle of a big city in zone 6, the plants are close to a structure and you're a gambling kind of gardener—just cut the plants to the ground around December and cover with a few inches of well-shredded leaves till Spring. Not sure of your summer bloomers' tenderness levels? Look it up at www.bulb.com
And remember—little to no food and very little water over that winter!Many more plants are killed by over watering and overfeeding than by drought and hunger. You Bet Your Garden ©2004 Mike McGrath