Tuesday, November 10, 2015

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Bulb Persuasion

By definition, "forcing" something like a delicate little 'Tete-a-Tete' daffodil to bloom out of season sounds mean and heavy-handed. So, rather than "forcing" spring bulbs to bloom in pots indoors ahead of season, let me be kinder, gentler and call it bulb "persuasion". It's actually very easy and rewarding if you know the right procedure.

Bulb varieties that respond well to persuasion

Daffodils, tulips, crocus, hyacinths and the minor bulbs require a prolonged and uninterrupted chilling period of 38-45 degrees F. (called vernalization) for 10-12 weeks to trigger flowering. If you want to successfully capture that same stunning garden effect indoors you need to duplicate this chilling process. If you don't, you'll just have grassy leaves with little or no flower display to show for your efforts.

You should know there's a wealth of ways to achieve a gorgeous result. Some standard methods to persuade bulbs to flower indoors are:  
  1. Pot the bulbs, sink the pot in the ground (to keep from freezing), cover with coarse mulch and pull out late winter to bring in and enjoy. Downside: Pots may be frozen in ground and inaccessible when you want them. Pots may be dirty and hard to clean.
  2. Pot bulbs, put out in your cold frame. Downside: Seriously, how many of your neighbors have a cold frame or are going to build one for four or five pots of bulbs?
  3. Pot, put in the refrigerator. Downside: Pots full of bulbs are space-consuming in the fridge, especially for the 10-12 week minimum needed for chilling. For those folks with a spare Frigidaire loafing in the garage this is a very workable solution.
  4. Pot, put the watered bulb pots down in a window well and mulch lightly, with straw, for example. Upside: I've learned that window wells are a largely untapped garden resource, but you have to have access to them. Whether it's winter storage of evergreen bonsai or the aforementioned bulbs, wells are really useful. You're putting things below the frost line, temperature extremes are buffered, too, by the ambient heat from the house and they get natural precipitation (unless plastic dome-covered). Win-win, love it.
Who doesn't love having bulbs (especially hyacinths) in flower in February and March while the garden is still under siege? I readily admit to trying a number of different bulb persuasion techniques over the years and I have a favorite. It's my favorite because it gives consistent uniformity of flowers and no rotten bulbs. I call it the bag-in-the-fridge method.

Dated bags of bulbs ready for 10-12-week chill in fridge

Put the bulbs for persuading in paper, ventilated plastic or mesh bags so there is adequate air circulation around them. Remove ethylene gas-producing fresh fruit and vegetables from the fridge before putting the bags in the crisper. Ethylene adversely affects flower buds in the bulbs and can cause them to abort. If you're like me it's best to put a date on the bulbs so you know exactly when the chilling started. 8-10 weeks is the minimum, 10-12 is better. So, if you're looking forward to winter blooms get them chillin' as early as possible.

Prechilled hyacinth potted up and ready to please




With the bags-in-the-fridge method pull them out at the end of their chilling period and pot them. A standard houseplant potting mix is fine. Whether you use clay or plastic the pots must have drainage holes. Don't do less that six (more is better) daffodils or tulips per pot. Single, double early and Triumph are the best tulip classes for persuading. Because of their large bulb size the very tip of tulips and daffodils should be above the soil line. With their incredible fragrance 3-5 hyacinths per pot makes a wonderful show.

Water thoroughly and place in a cool (60-65 degree F. would be great), dark place in your home while the plants commence rooting. That will generally take several weeks. When green leaf tips start showing in the pot you can move them to more light and warmth. Strong light, if not direct sun, and cooler rooms will give you strong, stocky plants. When the buds start showing color move away from sun and heat to prolong flowering.

Persuading bulbs this winter? It's in the bag...

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