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nafex - Re: [nafex] nanking cherries germination

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  • From: Sam Brungardt <samb@pop.isd.net>
  • To: nafex@yahoogroups.com
  • Subject: Re: [nafex] nanking cherries germination
  • Date: Mon, 4 Jun 2001 16:10:28 -0500

Title: Re: [nafex] nanking cherries germination
I got some pits from my nanking cherry bushes and I was going to see
if I could germinate them.  Is there anything special one needs to do
to the seeds first? How long do they take?


 
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The following info is from Hartmann and Kester's "Plant Propagation Principles and Practices" (1959 edition).

All temperate-zone Prunus species require a period of cold stratification.  To play it safe, give Nanking cherry (P. tomentosa) the longest stratification that is listed below--100 days at 32 to 45 degrees F before planting them in the spring.

Mazzard (P. avium or sweet cherry) seeds require a low-temperature stratification period of about 100 days at 35 to 40 degrees F.

Apricot seeds require a low-temperature (32 to 45 degrees F) stratification period of 3 to 4 weeks before they are planted in the spring.

Peach and myrobalan plum seeds low-temperature (32 to 45 degrees F) stratification period of about 3 months (90 days) before they are planted in the spring.

Cold stratification is the subjection of moist seeds to low temperatures for a specified length of time prior to germination.  This treatment brings about prompt and uniform germination of the seeds of many woody species which have dormant embryos.  Without cold stratification, seeds of these species either germinate slowly and erratically overa a period of weeks or months or fail to germinate entirely.

Seeds are prepared for stratification by soaking them for 12 to 24 hours in water.  The moist seeds are then mixed with two to three times their volume of a moisture-retaining stratification medium (such as vermiculite, sand, milled sphagnum or peat moss).  Suitable containers for stratification which provide aeration are boxes, cans, glass jars with performated lids, and polyethylene bags.

The proper temperature can best be maintained in refrigerated storage.  Or, the seeds can be stratified in the same manner outdoors over winter in a protected location by burying the container they are in 6-12 inches deep in the ground.  After the stratification period is done in the early spring, remove the seeds from their container, separate them from the stratification medium (a good way is to pass them over a screen that allows the medium, but not the seeds to fall through) and plant them in rows (a good rule of thumb is to cover seeds with dirt 3 times the thickness of the seeds.  Keep the nursery bed moist, but not soggy, by irrigating as needed.

And this is what the NAFEX handbook has to say about stratification:

The best seed for planting usually comes from fully ripe fruit.  Small quantities are pleasantly extracted by eating away the flesh; larger amounts can be obtained from the refuse of processing (e.g., cider pomace).  Sometimes, however the fleshy parts of the seed-bearing fruit will not be very good to eat.  In this case, the ripe fruit may be crushed, piled into a heap, and allowed to ferment for several days.  The seed is then separated from the pulp by washing and screening.

In handling the seed, some care must be taken to prevent loss of viability from excess drying out or rotting.  The seed should be washed immediately after extraction and then dried for a few days in a shaded, well-ventilated place.  Once dry, it should be stored under cool, low humidity conditions; many seed savers find a loosely covered glass jar to be an excellent storage container.  When ready for sprouting or planting, the stored seed can be rehydrated by soaking overnight.

Most common types of fruits and nuts require that their seed undergo a definite amount of chilling before germination will occur; seed from fruit ripening in summer and autumn normally remains dormant until the following spring.  The duriation and temparture of requisite chill will vary according to species.  Two to three months of temperatures befow 40 degrees F and above freezing is typical for apple and pear.  Stone fruits like peach and plum may require up to four months of chilling; almond and apricot seeds, however, have been known to break dormancy after only a single month of cool temperatures.

The stratification method of exposing seed to the required chill is known as stratification: seed is stored in a cool (32-40 degree F) place through the winter in boxes containing alternate layers of damp sand and seed.  After this stratification period, the swollen or freshly sprouted seed is planted out.  Many amateurs have found the household refrigerator to be an ideal place to stratify small quanitites of seed.  The seed is mixed with moist sand and/or peat moss, placed inside a plastic bag, and refrigerated 'til planting time.  Whatever the medthod of stratification, it is important that the seed be inspected regularly to monitor moisture levelws and determine time to plant.  Seed is best planted out just as germination is beginning.  In some instances, the start of stratification should be delayed to prevent premature sprouting; this is especially true under refrigeration, since the contant temperature may hasten the required accumulation of chill.

Propators living in a  temperature/cold winter climate zone often take a more casual approach simply by planting outsdoors in the autumn.  Seed may be started in flats or containers for later transplating, direct sown in a nursery bed, or evn planted out immediately into a well-prepared permanent site.  Most fruit tree seed will do best if planted between one and two inches deep, depending on seed size and soil conditions.  Acutal distance between seeds is determined in part by expected germaintion rate and vigor of growth.  For rootstock production, some crowding is desirable to prevent excessive or shrubby growth; two or three inches between seds is a common interval.

While autumn planting with natural stratification enjoys the obvious advantage of simplicity, there are cetain inherent problems.   Special attention will have to be paid to soil moisture levels to prevent drying out or rotting.  A raised bed system coupled with a light mulch should help maintain proper moisture conditions.  Weed control can also become a difficult problem in direct-sown seed beds.  Perhaps the most serious drawback to autumn planting arises from the unfortuante potential for rodent damage.  In many areas, a mechanical barrier such as hardware cloth is absolutely essential.  Where rodents remain a persistent threat to nut and stone fruit seed, it may be best to start stratified seed in a protected area and delay transplanting until later in spring.

 




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