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Help! Help! - A Germination Explosion !!
(How to slow down or possibly stop germination)

What kind of crazy statement is this, many of you may ask? What do you do if you expect not more than 2200 seedlings and have only bench space and growing lights (in the basement) for that many? Suddenly, within five weeks, I ended up with a bumper crop of 4600 seedlings!! For 25 years I was always disappointed with poor and sometimes zero germination. Now, this past Spring (my 26th year of hybridizing), the surface of my seed trays have literally exploded with growth. During my working years, I had never managed more than 100-300 annually (in the open) with a maximum of only 800-1000 seeds. Germination was usually from zero to 15 %, and seldom over 25 % . In 1993, my first full year of retirement, I increased the number of crosses to 900 (90 % minis) which gave me 550 hips and 3600 seeds. Only 600 germinated plus 350 more from the second year germination.

Note please: By April/May I let the seed trays dry out, store them, and from Oct. to Dec. I will give them a second cold period and I always get another 5-10% germination. (Especially those from yellow parents)

In 1994, I figured I could easily double these numbers so I bought more minis. I now had 106 minis which I put into two-gallon pots. Fifty-five of these seed parents were 'June Laver.' My number of crosses increased to approximately 2000 (under cover) which gave 1550 hips with a grand total of over 14500 seeds. 800 hips with appr. 8000 seeds were from 'June Laver' alone. I knew from last years seeds of 'June Laver' that I may get from 15-40 % germination. The interesting part of 'June Laver's germination is that one batch of 1000 seeds gave 10 % germination and another batch of 4000 seeds gave 40-48 %. The first batch of 1000 seeds had 6-7 weeks of 35º-37º F. steady temperature and the last two weeks they had a fluctuating temperature of 35º-45º F. outside. These took 3-4 weeks in my basement (60º-65º F.) before any started to germinate. After about 5-6 weeks germination stopped completely for a total of only 100, which is 10 %. I always water my seed trays about once a week until the end of April. Most times a few more would germinate after each watering. After this "only 10 %" disappointment, I estimated that I might only get about 2000 seedlings from these 14500 seeds.

Note: I always try to get my hips to at least 90 % orange before harvesting, then I shell the seeds, wrap them in paper towels and store them in my "roses only" fridge (35º-37º F.) until all seeds are harvested and then plant them into seed trays. Also note, because of our late growing season most hips are still green by mid- October and will not ripen outside in only 50º to 55º F. temperature. I then put all my potted seed parents into the basement under my growing lights to get all hips as orange as possible for better germination.

Now, finally, I get around to my so-called "Germination Explosion"! In this batch I had nearly 7000 seeds from hips 70-100 % orange. Four thousand of these were 'June Laver' seeds planted in two 10" x 20" trays of 2000 seeds each. These 4000 seeds had only two weeks at a steady 34º-37º F. in the fridge. After that, these seeds had 6-7 weeks of fluctuating temperature from 34º-55º F. and sometimes up to 65ºF. I gave the seeds this fluctuating temperature every second or third day. Finally, when 3 trays with nearly 7000 seeds were taken into my basement (60º-65ºF.) I did not expect any germination for another 3 weeks, when I thought I could expect 50 to 100 per day. Boy, did I miscalculate this time! Exactly six days later one single seedling poked through. Both trays with the 'June Laver' seeds exploded with growth. The whole surface of these trays looked like mountains and valleys with 1/4" cracks, like after an earthquake. All over, several quare inches at a time were lifting up 1/2" or so. When I carefully scraped the top layer away, I found hundreds of seeds sprouting at the same time and only 1/8 to 1/4 inches apart. ( No wonder with ten seeds per quare inch.)

My happiness in finally getting germination like never before in 25 years turned into frustration and desperation about 10 days later when I ran out of bench space and growing lights. Not just 100, but 200-300 seedlings appeared each day with a peak of 500 for one day. I was unable to keep up with transplanting for two weeks. I transplant my seedlings bareroot when they are one and not more than two days old. After only 3 to 4 days fine hair roots start to grow and seedlings may get a transplanting shock. I plant all my seedlings in Rubbermaid dish pans 11"x 14"x 5" high with about twenty 1/8" holes drilled for drainage. Each dish pan takes 42 seedlings when planted 2" apart. This takes less space and much less watering as when planted into little cups or pots. I kept buying more and more dish pans by the dozens and when germination finally came to a hold, I had filled 110 dish pans with 42 seedlings each. Trouble is, I only had space for 50-60 pans. Those 'June Laver' seeds gave me 40 and 48 % germination. I believe that my fluctuating temperatures probably increased my germination percentage dramatically.

Now I was faced with the biggest problems in my twenty-six years of hybridizing.
# 1 The seedlings need light and where to put them all ?
# 2 How do I slow down or possibly stop germination ?

I guess I solved problem # 2 by watering the seed trays only more time, one week after germination started. While I was trying to solve my space problem I still had my last 3000 seeds in the fridge which I kept there for an extra week. About 1500 of these seeds were 'June Laver.' Just as before, after exactly six days in my basement, another "GERMINATION EXPLOSION" occurred with another 1200 from those 3000 seeds. As before, by watering the trays only once, most germination had stopped within two weeks.

Now, you ask, where did I put them all??

The most important fact to remember is that the seedlings need light. So with day temperatures of 45º-50º F. and appr. 35º-40º F. at night, I had no choice but to take the overflow outside. Then a cold spell came with 25º F. at night. Every night I carried 25 or more dish pans into my basement. The cold nights lasted for more than a week and something drastic had to be done. I added a temporary bench with four lights for 800 seedlings. This was not enough. I then bought more lights and put more shelves and boards over, under and in between the existing benches to house an additional 1000 seedlings. Finally, in March, no more frost at night! 3800 seedlings are now inside under lights, but the last 800 had to go outside again. I am glad my germination has stopped as suddenly as it started. All my seed trays have dried out now, about six weeks earlier than in other years. I will probably have another 1000+ seedlings from those 14500 seeds by next spring. (Second year germination). These past five weeks have been the busiest ever since I started hybridizing in 1969.

POSTSCRIPT October 1995: For the next 2-3 weeks after 25 March there were another 150 seedlings germinating to make it a total of 4750. More than 95 % of the seedlings were eliminated inside after their first bloom. (7-10 weeks after germination). By early July, only 140 were left, planted in pots and put outside for further test. The seedlings were only sprayed to kill the thousands of aphids appearing every summer. No fungicide was ever sprayed -inside or outside-during the summer. By October, another 40 seedlings went into the trash can, mainly because of mildew and poor blooms. Now there are only 83 miniatures, 18 floribundas, and 1 hybrid tea left for next years test.

ADDENDUM February 2001: After this many years, those left of the 4750, I can count on my fingers. After my 1994/5 "Germination Explosion" I scaled down and made only 800-1000 crosses per season. I have always given my seeds the fluctuating temperatures since 94/95, but never ever did I get a 40 to 48% germination again. The most I ever had, not even from my 'June Laver' seeds, was a maximum of 25 % germination. I can not explain why this is. But as I always say to friends who become interested in rose hybridizing: "It is 99 % luck and only one per cent planning". The same may also be applied to germination percentages.

by George Mander
March 1995

(first published in the Rose Hybridizer's Association newsletter)

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