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Forcing: A New Winter Hobby
By Karine Pierson, Extension Master Gardener Trainee
C.H.A.D. Compulsive Horticultural Acquisition Disorder – The obsessive need to acquire new plants, whether you have room for them in your house.
Do you ever get bored in the winter, suffer from C.H.A.D. or just develop an itch for gardening during the colder months that cannot be scratched by just looking at seed catalogs? Forcing is a new winter activity for you that can keep you occupied (read: fascinated), and your environment filled with beautiful blooming plants all season long. I am going to share with you several planty activities that you can occupy your itchy green thumb with when the ground outside is frozen. These plantings can be done and enjoyed inside from fall to early spring. The difficulty level of these projects varies, but even a brand-new beginner can learn to force, which we can think of as coaxing plants into bloom inside when they normally would not be blooming, like the middle of January. All of this and more can be accomplished, but let us start with something a little more on the easier side.
Difficulty level: Easy
Amaryllis is one of the easiest bulbs to force. It is in a group of what are called “tender” bulbs, as in bulbs from the tropics – the opposite of hardy bulbs we grow outside here in our temperate climate, such as tulips and daffodils. These bulbs have an opposite growing season than we do, being that they are native to areas south of the equator. You may be familiar with tender bulbs such as cannas and dahlias, which are planted outdoors in the garden and then are dug up for storage in the fall. Amaryllis bulbs will start to appear in gardening stores and big box stores alike in late November and December. It is a traditionally festive plant for the holidays, since they are usually red, or red and white in color. You may see “Paperwhite” narcissus bulbs for sale with these, which will also bloom around the same time period, and are ridiculously fragrant. Get a few of these bulbs going together and your holiday parties will be the talk of the town. All you must do is open the package and rehydrate the coco coir it came with as a growing medium. Sometimes this comes in a weird dry disc and that is ok, just make sure it is fully hydrated and it will turn into soil. Plant the bulb root-side down (the fat part) and if a little sprout is already coming up that is a bonus! Water whenever the growing medium dries out (stick your finger in it to feel the moisture level) every few days or so (more as it grows), and in about four weeks you will have giant blooms. Trellis so they do not fall over, they are infamously heavy and impressive.
Difficulty Level: Moderate
Another of the tender bulbs, this is a new plant to me. Clivia was popular from the 1800’s until the 1950’s. It is a throwback bulb! I have just purchased it online for $7.99 and it arrived alive from California in three days. I have transplanted it, and I am sending it good vibes that it will come out of dormancy and begin to make little sprouts during which time I can begin to water and pamper it. They do not like being repotted nor do they like wet feet, especially during the dormant period. It is the perfect plant for those with little light. Stick it in the darkest corner of your home. You do not water it four months out of the year, so it is a lot of reward for very little effort. Once it comes out of dormancy, gorgeously detailed orange flowers will appear, which I will deadhead for more blooms. It should bloom the entire month of March and then I will be left with the beautiful glossy, evergreen foliage for which this plant is famous. Water all through summer until the first day of November. On that day, stop watering and do not begin again until the first day of March next year. I am going to assume my little plant will still bloom in March because it is going to sulk a bit in its new pot after being transplanted before it will decide to grow. I will keep you all posted on this new child.
This is my new Clivia plant pouting in the corner after transplanting. Its root structures resemble those of orchids, so I used orchid potting soil.
Difficulty Level: Hard (pun intended)
Have you ever wondered how wonderful little pots of daffodils, tulips, and fabulously scented hyacinths are grown so that they appear in early spring, just in time for everyone’s cabin fever to be at a level ten? The answer is forcing! Plant these bulbs in a potting medium with good drainage the second week of October or so, and if things turn out just right, in the spring you will enjoy a dazzling display of color and scent. The trick is to have the right places to put the plants in the right temperature at the right time, and this can be challenging. Get out your trusty thermo-hygrometer for this task and take temperature readings in places in your house such as a garage, basement, and attic. They should start out at about 40 degrees (a chilly, but not frozen garage) for the first and longest period where you will be mimicking winter. I would not advise using a refrigerator for this because the bulbs will not grow next to gases that emit from ripening fruits like apples. Keep this in mind when deciding where to put the bulbs. If you have a bunch of pears from your pear tree curing in the garage for example, it is not best to put the bulbs next to them. For about 12 weeks water them and keep them cold. About two weeks before blooming, they will need to go in a little bit of a warmer spot at 55-60 degrees or so with low light. A north-facing window is perfect for this. You are now mimicking early spring. After a couple of weeks of this, you need to put them in a nice sunny spot or under a grow lamp (to imitate late spring), and blooms should burst forth! After the blooms come up, you can place the plant anywhere you want in the house as light is no longer a factor. If you buy forced plants like this at the store, remember they do not need light as they are past the period where it is necessary for them, so you may place them in your darkest, most windowless room for some spring cheer.
Twigs and Branches
Difficulty Level: Easy
Anyone can bring branches and twigs into bloom. Simply gather some branches with buds from spring-blooming trees and shrubs, and/or trees with interesting leaves such as red maple and willow any time from the end of January until the second week of March. Place the branches in your bathtub in lukewarm water and soak for two hours. Next, you will arrange the branches in a vase of water and place them in a windowsill where they will see natural light or even under a grow light. They should start to bloom before the trees outside bloom, and you will get an early show. The warmer the weather when you harvest, the better-suited the branches will be for forcing so aim for a rare winter sunny day. Trees in Northern Michigan suitable for forcing are as follows:
Redbud, Pussy Willow, Forsythia, Spirea, Witch Hazel, Staghorn Sumac, Wild Cherry, any fruit trees
Use your imagination, the possibilities are endless!
My redbud tree is brand-new this year and struggling, so probably not the best candidate to take branches from.
Once the branches come inside, they need a good soak in a sink or tub at room temperature water, so I set a timer for two hours.
Miscellaneous Forcing/Indoor Gardening
Difficulty Level: Various
There are many other types of forcing, including water forcing which is where the bulbs are placed in vases of water instead of soil. This is commonly done with hyacinth bulbs. There are also many other types of bulbs not mentioned previously that can be forced, including the weird and wonderful Bowiea plant or the ‘Walking Onion.’ There are also other ways to indulge your inner gardener during the winter such as growing and propagating house plants and starting seeds. These activities can be done at any time, but be aware if you are going to germinate seeds for your summer garden, each plant has a specific timetable as to when to start it. Onion seeds are started in January, tomatoes and peppers in March and squashes, pumpkins, and cucurbits about three weeks before the last frost. I highly recommend getting a grow light, a humidity dome, and a heat mat if you are going to start seeds for the summer garden, as these items ensure success. Seedlings like it warm, like most babies do.
Cheers! In the bottom of the glass is an organic Mandarin (dwarf) orange seed I obtained from a delicious Mandarin from a local food co-op. The trick is to not let citrus dry out prior to planting since it is a tropical plant from a wet environment. Direct-sow in a pot of seed-starting mix and keep watered once a week for six weeks and a citrus sprout should come up. As a rule of thumb, always start at least two of any fruit trees to ensure pollination and in case one does not make it. Let us be honest, many do not make it and it will be years before we ever see any fruit, but it is fun to try right? In the photo below is the result of one of these seedling experiments, a baby lime tree, thorns, and all:
Tips for forcing plants:
Choose a nice-looking container I cannot stress this enough, especially with forcing twigs and branches. They look elegant in a nice vase, really ‘meh’ in your old mayonnaise jar. Twigs and branches also pair nicely with other forced bulbs.
Raise the humidity level in your home with a water feature, such as a small water fountain or a simple humidifier. This is good for your skin in the winter too, when humidity levels can get as low as twenty percent. Keep track of it with a thermal hygrometer, which is a handy little device that reads both temperature and humidity. Actively growing and flowering plants like a general humidity of 50-60%
Choose safety for your family
Some tropical plants, garden plants and bulbs are extremely toxic to children and pets, including iris and daffodil. If you have kids or pets, do your research before you buy plants. Obviously call your doctor or veterinarian if you fear that your family member, furry or otherwise may have ingested plant material.
Use better water
Distilled water is better for plants than tap, and well water is best. If you must use tap water, let it sit out for 24 hours to evaporate some of the chlorine and synthetic chemicals.
The possibilities for winter and indoor gardening are endless! With a little preparation and some planning ahead, you will not ever be forced to be bored or plant less during the cold season again!
For Further Reading:
“Forcing, Etc.” by Katherine Whiteside (Smith & Hawken)
This is the quintessential book on forcing, and I highly recommend getting it if this subject really interests you and you want a lot of details. Everything is covered here.
“Bulb Forcing” by Art Wolk
Art Wolk is a humorous expert in bulb forcing, and this book is an intensive, scientific discussion of it.
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The Trials and Tribulations of Indoor Gardening
By Molly Bacon, Extension Master Gardener Trainee
For about 25 years I have had greenhouses, while living in both Tennessee and Georgia prior to coming back to Michigan. They were heated, had automatic misting systems and a large thermostatically controlled fan. I started out with orchids, which I had also grown while living in Southern California, and later added potted citrus. I did well with the orchids, having some award winners at shows being judged by the American Orchid Society. Unfortunately, once the trees surrounding my greenhouse grew larger, they drastically reduced the lighting to where I could no longer grow orchids. I continued with the citrus, which spent their summers outside and then I finally gave the citrus and the greenhouse to some friends in Florida.
Here in Michigan, I have a small south-facing room with three windows and no heat. It also has a day bed, my collection of lightning rods (that were acquired since this photo), and some miscellaneous knick-knacks.
Last year, I decided to venture back into trying potted citrus and a couple of fig trees. This was before my Master Gardener training. In October 2019, I brought in the citrus, some poblano peppers, strawberries, and artichokes. I Added an oil-filled heater, a borrowed 4 foot- 2-tube grow light, a three-arm table-top grow light, and a small table-top fountain. The artichoke pot brought in a horrible case of fungus gnats and the artichokes slowly died. My experiment of over-wintering 3 pots of poblano peppers wasn’t worth the space and the strawberries also died. Somewhere around the holidays, I acquired a Thanksgiving cactus and in the spring an amaryllis. The citrus stayed alive and in March, the Meyer lemon bloomed and then promptly dropped all its leaves.
I also tried my second year at seed starting. I added an additional 2 foot- 2-tube grow light suspended from the shelf above. Even seed starting was not totally successful since the seed starting media was very inferior and would not evenly take up moisture no matter what tried. Consequently, those seeds either did not germinate or died shortly after germination.
Once the weather warmed, I moved everything outdoors. Most of the plants did okay when I remembered to water them.
For this winter, I spent some time planning how to better utilize the limited space and make the garden room more successful. I replaced the borrowed 4 foot grow light with one I purchased, and I added one of the halide lights that the professional growers use. I was lucky to find it for $5 at a yard sale down the street this last summer. I knew I needed much more humidity than the little table-top fountain provided, so I purchased a humidifier rated for more square footage than the room is large. Last year, I set the citrus pots on upturned 5-gallon buckets but did not like that arrangement. Since the room is carpeted, I placed an extra-large dog kennel tray under the citrus even though they are also on drainage saucers. This tray helps collect accidental water spills and drips from misting. The house is on a raised foundation and the floor gets cold in the winter, so I added a large heat mat under the tray with the citrus.
From my former days of selling antiques and “stuff”, I still had a vintage 5+ foot high wrought iron plant stand shaped like a spiral staircase with a larger potholder on top. I am using it to hold the now two amaryllis since I’ve acquired a second plant, Thanksgiving cactus, the smaller fig tree, and a Hoya carnosa ‘Krimson Queen’. I had a large Hoya plant in the greenhouse in Georgia. They have such unique waxy flowers. Can you believe, there is actually a Facebook group of just Michigan Hoya growers.
Yes, my room is really packed full. Eight citrus trees, a dwarf pomegranate, two figs, three Hoyas, Thanksgiving cactus (1 large and 4 small pots from the large one falling and breaking apart), Easter cactus and 12 recently acquired Christmas cactus cuttings, eight orchids, and finally last year’s pot of parsley and a cucamelon or mouse melon (Melothria scabra). I had read where cucamelons grow tubers and can be over wintered and replanted again the next year. Though my pot had gone through the fall freezes a couple of times, it thinks it is becoming spring in the back corner of the garden room and its vine is now about 3 feet high.
Now to my biggest mistake of this year. Being too busy which I know is no excuse and kidding myself into thinking it is was not that bad, I let a horrible spider mite infestation take over all of the citrus plants. They started dropping leaves and were looking really shabby. Shame on me, a new Master Gardener trainee. One morning I moved them all out of their corner and one by one with cotton swabs and insecticidal soap, I swabbed them all down and then drenched them with a spray bottle of insecticidal soap. I have started a daily misting routine and repeated incremental insecticidal sprays to, “fingers-crossed”, break the life cycle of the mites. Fewer leaves are dropping, except the Palestine Sweet Lime, which like the Meyer lemon last year, was beautiful, bloomed profusely, and dropped most all its leaves. It was not all the leaves but about 98% of them.
Just when you think you have it figured out; they surprise you. Of course, it is not like I pick normal houseplants to grow so I think it is expected that there will be surprises.