Winter is a good time to turn my thoughts to propagating plants. Although I live in the south (Georgia) some days are really miserably cold, windy and rainy. What better time to learn up on new propagation techniques.
Oaks
Oaks do not transplant easily. Even young oaks seem to have interminably long tap roots. And it is difficult to tell a small sapling young oak from a 5 or 10 year old sapling old oak since oaks are content to bide their time in the shade of larger trees until the umbrella is pierced and growth giving light encourages them to get going. I walked the woodland yesterday looking for acorns and found none though there are many >20 year old white and red oaks. At first I thought they may not be producing acorns since they are hemmed in on all sides by pines and tulip poplars. But then I remembered all the oak saplings surrounding these trees and concluded that squirrel or deer had been feasting on the mast (as it is called). Too late to the party. However, in Sandy Springs, Atlanta near our suburban home there is a huge oak tree which has littered the sidewalk with thousands of acorns. I collected 100 this morning and seeded them 25 rows, 4 each, 1″ depth, in a new long raised bed I have built. I shall water, keep an eye on them and, with some luck in early summer there may be signs of life.
Fruit tree cuttings
I mentioned in an earlier blog that I am new to cuttings and a reader gently nudged me to a better understanding of the mechanics, for which I am thankful. You have to establish first if you are dealing with hardwood or softwood cuttings. Hardwood is not necessarily harder than softwood and an example frequently quoted is balsa wood, which is a very light wood but is classified as a hardwood. The distinction is based on the seed and the seed of hardwoods has a covering, such as fruit or the hard shell of an acorn. For hardwood cuttings you take the samples in fall or early winter.
My neighbor agreed that I could take cuttings from her many fruit trees, so this morning, with my alcohol sterilized secateurs, I took snips from a number of her trees which include mulberry, cherry, pear and apple. From these snips I prepared >20 cuttings and rather than using a heated tray and remembering to water and bothering the cuttings with weekly inspections to see if the roots had arrived, I simply prepared a V trench in my outdoor raised bed (which has frost cover protection) and planted them and watered them. And I will look for buds in the spring.
I know that apple trees should be grafted on appropriate stock but what I want to achieve, rather than a formal orchard, which I already have, is an informal association of fruit trees interspersed with edible or useful perennials. Since the cuttings are from trees which have thrived in this area, they should be able to take good care of themselves.
Seed germination
My real pursuit has been learning more about seed germination. Through the comments of MikeH on this website I learned of “Seed Germination Theory and Practice” second edition by Professor Norman Deno (“Deno”) published in 1993 and available for free download. For anyone interested in this topic, this book is great.
Previously I didn’t understand why, although most seed germinated in warm moist conditions, other seed needed cold to germinate and some seed seemed completely indifferent to my efforts.
Deno germinated nearly 2,500 species and the processes he used were relatively simple – he did not use pots and growing media, instead paper towels and polyethylene sandwich bags (thin bags not sealed too tightly so as to maintain aerobic conditions). For some species he used gibberillic acid. He conducted his germination tests at just two temperatures 40 or 70 deg F. Based on the results of his research he developed a number of principles such as all species have mechanisms to delay germination until the seed has been dispersed. There can be multiple mechanisms such as required sequences of hot and cold temperatures, or cold and hot temperatures, or oscillating temperatures as well as a time clock and/or the need for light or dark etc.
I find interesting why species have particular delay mechanisms and it seems the mechanisms are about ensuring survival of the species. If seed dropped in summer were to germinate in summer, the tender offspring would be killed by winter, hence a programmed requirement that there must be cold (i.e. winter) before the seed can germinate. Apparently for plants growing in swamps or woodland, where having enough light is a bigger problem than having sufficient water, the seeds require light to germinate. Apparently for plants in cold desert areas where moisture is only available in the spring, the seed will germinate at low temperatures in order to be sufficiently developed to benefit from the spring rains. Some species produce quantities of seed coats which are empty and Deno speculates that this is also a survival mechanism – predators which exert themselves to open the seed coats and then find nothing there will lose interest in that particular seed. Some seed require cold then warmth then cold i.e. two winters. The survival mechanism here could be that if all the seed germinated the following year and conditions were bad – drought, fire etc, then the entire species could be destroyed. So requiring two winters appears to double the chances that the species will survive. Fascinating!
I now understand why if you cut a flower before it has seeded, taking care to leave buds on the stalk, the plant will flower again, and if cut, again. A survival mechanism requires the plant to keep trying to flower so that it will be pollinated and produce seed. Once it has produced seed it has achieved its mission. Not to say plants are indifferent to human desires. Another survival mechanism could be to look beautiful to humans (in addition to the pollinating insects) so that humans will favor them and propagate them.
