Elevating Tulips

By Larry Rettig (LarryR) on November 23, 2011

Just like that pair of jeans in one's closet is often the foundation of one's wardrobe, so tulips are a mainstay, not in closets, but in spring garden beds all over the world. From those early days when species tulips were first collected in the wilds of Kazakhstan, to the frenzied “tulipomania” that gripped Holland in the 1630s, to the thousands of varieties that find a home in gardens today, tulips have become one of the world’s most easily recognized and beloved flowers. It appears that their popularity may soon take a new direction.

recently came across a fascinating study at New York’s Cornell University that deserves to be more widely known.  The goal of the research was to find ways to make tulip planting easier, but, as we’ll see later, with the development of an unexpected twist.  Here are the two questions that drove the plant scientists’ inquiry: 

“Can we come up with ways to make it [bulb planting] easier for people?”
“Can we find methods that might allow more people to plant more bulbs more often?”

The one experiment that blew me away--and may well revolutionize tulip bulb planting methods--involved the following procedures.  Three foot by three foot beds with soil tilled eight inches deep and amended with a slow release bulb food were planted with 16 tulip bulbs each at various depths.  Planting depths ran as deep as six inches all the way up to zero.  That’s right, zero!  Those bulbs were simply laid down on the tilled soil. 

Next, all beds except two were covered with double-ground mulch.  The mulched beds, by twos, were covered to a depth of either two, four, or six inches.  All mulched beds had wooden frames to contain the mulch so that depths would remain even. 

The tulip varieties used in the experiment were ‘Ad Rem’ and ‘Negrita.’  They were allowed to flower naturally over a period of three years and received only natural rainfall.  In the fall any beds where the mulch had settled below the specified depth were redressed and the mulch depth restored. 

The results were absolutely astounding.  The bulbs that were just plopped on the ground and covered with two to four inches of mulch performed amazingly well.  In fact, they performed better than those planted at various depths in the soil!  Remember that this trial took place at Cornell University in Ithaca, New York.  That’s gardening zone 5, where winter temperatures drop as low as -20 degrees Fahrenheit. 

Here are the results for the two tulip cultivars used in the experiment, expressed in the number of flowers per year:

'Ad Rem'     
Mulch Depth Flowers in 2009 Flowers in 2010 Flowers in  2011
2" 14  17 28
4" 16  20  20
6" 14  19  16
Mulch Depth Flowers in 2009 Flowers in 2010 Flowers in 2011
2" 14 32 28
4" 14 33 21
6" 12 22 17

Bear in mind that each bed originally had 16 bulbs, with each bulb normally producing one flower.  ‘Ad Rem,’ at a mulch depth of 2 inches produced 28 flowers this past spring.  That means that the bulbs are actually multiplying from year to year.  ‘Negrita,’ in its second year and covered with either 2 or 4 inches of mulch, more than doubled the number of flowers!

And what about the two beds that had bulbs placed on top of the soil, but were not covered with mulch?  The bulbs soon disappeared, most likely a banquet for rodents living in the vicinity.

Unfortunately, I came across this study too late in the fall to try it this year.  But by planting time next fall I definitely plan to be out in the garden with tiller, frame, tulip bulbs, double-ground mulch and fertilizer in hand.  I can’t wait to see what develops!


 Endnotes:  Tulips can be planted any time before the ground freezes.  The optimum time in Zone 5 is from mid-September through early November.  I may tack a piece of screen or chicken wire across the top of each frame to keep varmints out.  I'll remove it in spring, once shoots appear above the mulch.  I may want to just lift the whole frame off, screen and all, and then replace it at the end of the growing season.


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About Larry Rettig
"An enthusiastic gardener for over 50 years, my first plant was a potted Ponderosa Lemon tree ordered from a comic book ad at age 15. I still have it, and it’s still bearing lemons! My wife and I garden on 3/4 of an acre, both flowers and vegetables. Our garden, named Cottage-in-the-Meadow Gardens, is private and is listed with the Smithsonian Institution in its Archives of American Gardens. It is also on the National Register of Historic Places. We garden organically and no-till. Our vegetable garden contains a seed bank of vegetables brought to this country from Germany in the mid-1800s by my ancestors. My latest book, Gardening the Amana Way, is available at Amazon.com.

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Comments and discussion:
Subject Thread Starter Last Reply Replies
Very interesting. Zanymuse Nov 30, 2011 8:27 PM 8
Valuable information SongofJoy Nov 26, 2011 12:59 PM 1

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