Bulb Forcing Chilling Time

Yes, it's early August and most of us aren't thinking about forcing flowers bulbs.  I know!  Here in north Idaho, the harvest season is just barely starting, my early started cherry tomatoes have produced 1 ripe one and the beans are still a week or so away.  Sadly, our raspberries are almost done and it was our best crop so far!  Of course when thinking about forcing flowers, you have to think months in advance, as they have a long chilling period.  Which leads to the topic today - chilling time.

Before I start, I probably should do the standard disclosures.  My wife, Cathy, runs Season Extenders, LLC. which sells the only product designed for forcing bulbs.  It also can germinate seeds.  These blogs will not be focused on selling The Bulb Box, but some of my experiments will likely involve it.

Now, on to the chilling experiment we ran.  So, what about the chilling requirements for tulips?  The Washington State University Extension Agency flyer on forcing bulbs states 15 weeks.  Online, I've seen other colleges state 15-23 weeks, and other postings online with as little as 10 weeks.  So, if I'm going to force tulips, do I have to let them chill for 15 weeks?

I decided to run an experiment where I didn't provide any chilling at all.  My expectations were that I'd get no flowers and perhaps no sprouting.  My results:

• Muscari - extemely delayed and strung out flower generation with normal flower height
• Tulips - extremely delayed flower generation.  Flower stalks were about 2 inches high, funny sort of burned look to them, odd and disfigured
• Daffodils - no flowering at all

The flowering was so delayed that those with normal chilling flowered before the no-chilled ones.


Another example is the picture of Muscari and Princess Irene tulips.  The Irene is listed as an early bloomer.  I suspect their chilling requirements are 15 weeks.  The ones in this picture have only 11 weeks:

All the tulips flowered, but note how tall (short) they are compared to the normal height Muscari.  They sure look pretty though and look even better when it's deep in the January winter!  Below is another picture with Princess Irene, Freeman, Tete a Tete, and again Muscari.  These have had 18 weeks chilling:

Comparing the Princess Irene against the Muscari in the two pictures really shows the shortening effect lack of proper chilling time creates. 

In closing the loop on this experiment, each bulb variety has it's special chilling requirements.  If you want pots with the tallest flower heights, you will need to chill them for the full period, which may vary if you have a mix.  However, after seeing my results, they still produce beautiful displays of color and allow me to display more pots during the winter season!

Till next time,
Darrell

Bulbs and Season Extenders Welcome

Welcome to yet another gardening blog.  As the title says, this one is dedicated to forcing flower bulbs and other season extension techniques and occasional digressions as seems appropriate.  A little introduction and gardening background is probably a good way to start.  My name is Darrell and I live in a zone 5B in a North Idaho snow belt.  As an Engineer, I have a habit of dabbling in improving things and the long winters here have lead me to the hobbies mentioned above.  Our winters can really vary!  At times we have 6 - 8 feet of snow and it lasts forever.  Other times we have winters like this last one, reasonably warm (low of 0 degrees F) where I only plowed once and the kids never got a chance to sled. 


Well enough about me.  For starters, I think I'll talk a bit about one of the most influential gardening books I've read, Four-Season Harvest by Elliot Coleman.  Driving me is the periodic food contamination in our national system and the desire for my kids to taste vegetables as they should taste.  If I don't show them how it should be, who will??  Anyway, Mr. Coleman's description of the 4 season harvest really caught my eye so I decided to do my version of his plastic hoop setup with floating row covers.  Living on a rock "ripple" left by the pre-historic floods here has me using raised beds with soil I brought in.  To accommodate crop rotation, I designed a greenhouse that could be split in half for moving and re-assembled over the next bed the following year.

Greenhouse December 2007

Inside Greenhouse

It's made of welded rebar with slit poly-pipe from Home Depot.  Over it all is a layer of UV resistant gardening plastic.  The poly-pipe is to keep the rebar from wearing holes in the plastic.  For clamps, I have small sections of poly-pipe that I've slit down the center.  With the plastic , the pipe and plastic combo is just a little larger than the inside diameter of the "clamps" so they hold on well.  The corners of them do need to be trimmed on a diagonal to keep from inadvertent slicing of the plastic sheet.  Anyway, enough with the construction.  The execution went quite well despite one of the heaviest snow winters we've had in a long time.  I planted a lot of spinach, arugula, carrots to try Mr. Coleman's "candy carrots", and various greens that he recommended but I've never tried (red kale, miners lettuce, claytonia, etc).


It worked out really well.  However, if I had done a better job with my timing, I would have had a better combination of late Fall/Winter and Winter/Early Spring crops.  We kind of just ignored the carrots which we had actually planted earlier in the year.  They hadn't done very well, so had been left alone.  Anyway, when eaten after winter, they really were quite sweet and an unusual treat.  In particular, I like the convenience of having a good crop of arugula - I love a bunch on a meat sandwich along with some dill pickles.


Two topics come to mind for the next post.  I am not sure which I'll pick:  a failure I had extending the season for some rosemary or an aspect of forcing bulbs.


Till next time,
Darrell