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Propagation of deciduous fruit trees and vines by seed,layering and hardwood cuttings
Commercial propagation cannot withstand failure. As such, many fruit trees are grafted, primarily because this method of propagation provides a consistently high rate of success and fast multiplication for new varieties. Grafting is also an alternative where rootstock properties provide an advantage over own rooted trees (ie dwarfism or tolerance to moisture stress, different soils or disease). Regardless of the reasons, many fruit trees can be easily propagated from cuttings. Grown on their own roots these easily provide additional trees that are the equal of their grafted counterparts. Alternatively, many fruit trees can be grown from seed and either provide a worthwhile tree quite quickly or at least a rootstock for grafting. Germination of fruit tree seed The time taken for many seedling trees to reach a bearing age is comparable to the time taken for bare root trees to start cropping consistently (3-4 years). As seed is generally free and the chances of decent fruit are good, it is a risk that often pays off. Seedling trees that prove inferior can be grafted over to good cultivars and, due to the large rootstock, can begin bearing in the following season. Stratification Most deciduous fruit tree seeds require a period of cold stratification to break dormancy (Table 1). This is most easily achieved by placing the cleaned seed in water for 1-3 days. The hydrated seeds are then soaked in a 1:9 parts household bleach:water solution for 10 minutes to kill diseases. The sterilised seeds are rinsed clean with cooled preboiled water and placed into a plastic bag. Some damp paper, peat moss or vermiculite can be added to the seeds during stratification. However, it is unnecessary and the addition of other materials makes it more difficult to observe seeds for germination or infection. As long as seed is checked often and a few drops of water are seen in the bag, seed is unlikely to dry out and infected seed can be quickly removed or retreated. Seed are normally stored in the refrigerator at ~4oC and often begin germination while under cold storage. They should be checked once a week to remove diseased seed and determine if they are germinating. Table 1: Stratification and time to bearing for trees
*2-4 weeks 25oC moist stratification prior to cold treatment
Planting If seeds have not germinated by early spring and have rested for a sufficient time, they may be planted out into a seed bed (10 cm spacing with 15 cm between rows) or pots. It is often recommended that the seed coats be cracked or removed for heavily armoured seeds like prunus species. Without access to good fungicides this creates more trouble than it is worth in a home situation. It is better to plant three seeds per station or pre-germinate seeds than spend the time removing seed coats. Tree seeds need comparatively little moisture to germinate and over-watering is a major cause of failure due to fungal infection. Seedling aftercare Given optimum conditions pome and stone fruit seedlings grow very fast and can reach 2 meters and 1 cm thickness by late summer. However, in the home garden it is difficult to achieve this rate of growth unless seedlings are grown in the ground or in larger pots and fed liberally with nitrogen. Caring for the taproot and root structure of young seedlings is very important and the selection of pots is critical for good continuous growth. The best pots for initial planting are larger tree tubes (70 mm square) followed by a 150 mm tube. Milk cartons are also very good. Of course, good soil should be used in all instances and slow release fertiliser is very beneficial.
Apple and Pear Apple and pear trees are highly hybridised cross-pollinated plants. As such, only about one in four trees will give fruit comparable to the parents. Trees also undergo an undignified thorny juvenile stage. Seedlings are very vigorous and trees grown on their own root can reach over 20m in height on good soils. Consequently, it is not recommended to grow apples or pears from seedlings unless they are to be grown for rootstocks on poor soils where the additional vigour and drought tolerance is needed. Cherries Cherries are either self or cross-pollinated and will give acceptable but generally average sized fruit, about 1 in 10 trees will give very large fruit (<3 cm diameter). Seedlings are very vigorous. Cherries are big trees and while there are dwarfing rootstocks available (ie colt) they only reduce size by about 25%. It is better to employ a ‘Spanish bush’ pruning system to keep cherries to an acceptable height. Loquat Loquat produce variable fruit from seed. Having said this, very little selection has been undertaken in Australia to cultivate good quality varieties and purchased trees are, more often than not, sold for ornamental purposes rather than the quality of their fruit. While seedlings are very vigorous, it is more productive to conduct a survey of local trees and select one that has good fruiting characteristics for grafting onto seedlings. Gingko Ginkgo are dioecious (male and female on separate plants) and begin bearing from their 40th+ year. Seedlings are very slow growing and average 10 cm their first year. Seeds are very susceptible to fungal infection and are best pre-sprouted prior to potting up into a sterilised soil mixture. Grafting from known trees is recommended. Gingko sold at the nursery are invariably male plants as the butyric acid produced by the female fruits is considered a nuisance in ornamental cultivation. Peaches, nectarines and apricots Peaches, nectarines and apricots are self-pollinated and generally give excellent fruit. Seedlings are very vigorous. Fay Elberta (midseason) and Golden Queen (late season) peaches are commonly seed grown for rootstock and produce consistent good quality fruit. Persimmon Persimmon are self or cross-pollinated or they may be parthenocarpic (produce fruit in the absence of pollination and are seedless). They produce excellent fruit from seed and begin bearing in their 5-6 year. This is not bad as bare rooted trees are very slow to begin bearing. About 10% of seeds have no dormancy and germinate within a couple weeks outside the fruit. Without warm growing conditions these usually fail during the winter. Seedlings are slow growing and average 20 cm their first year. Persimmon seed must be planted with its pointy end up. If this is not done the seedling has great difficulty extracting its cotyledons from the seed coat and it invariably fails. They also require quite high temperatures (+25oC) to germinate compared to other deciduous fruit. Astringency is dominant, so if an astringent cultivar is involved in the pollination then all seedlings will be astringent. Seed are becoming increasingly difficult to find as nurseries are only selling 100% female non-astringent varieties and without pollen in the population there are no seeds. Do genetic variability a favour and plant some male trees. Plums Plums (European or Japanese) are cross-pollinated and fruit can be quite variable as myrobalan plums often contribute to pollination and are the cause of quite small fruit. Seedlings are very vigorous. Quince Quince produce good fruit from seed. Seedlings are very vigorous and quince is a valuable dwarfing rootstock for loquat, or quince compatible pear varieties. Most quince cultivars strike easily from cuttings so seed is seldom grown. Mulberry Mulberry cross-pollinate very easily and may produce variable but always good fruit from seed. Seed are extracted by macerating the fruit and soaking in water for a few days before the pulp is floated off, a food processor may also help. Seed should be stratified immediately after extraction as it rapidly looses viability. Seed is often grown as a rootstock.
Hardwood cuttings Many fruit trees can be easily grown from dormant hardwood cuttings. Commercial rootstocks are selected for their ability to strike this way and can be easily propagated from the suckers produced on orchard trees. Taking Cuttings Hardwood cuttings are taken after leaf drop from early autumn to late winter. Cuttings comprise at least 12 cm long sections of current season wood. The bottom of the cutting should be cut at a node and, to prevent excessive desiccation, the top cut should be sealed with melted wax. The cuttings are taken, bundled together, labelled and left in a cool dark place for a day. Cuttings are wounded by slicing the bark with a knife and dipped in liquid (3-5 ppm) or powder (5-8 ppm) rooting hormone. The top of thebundles are wrapped in glad wrap to cut down moisture loss and the root ends set into a heated bed at 15-25oC to callus over for 2-4 weeks. Beds are filled with a standard cutting mix (perlite/sand/peat etc.), which is on the dry side. The tops must remain cool enough at this stage to prevent bud break (ie less than 10oC). Once they are well callused or root initials are observed the heating is reduced slowly over a couple of weeks to harden them off and they can be left to root when temperatures rise in the spring or they can be set out in the field. Field grown cuttings must not be left to dry out over winter and should be watered regularly. It must be noted that heat bed callusing is not essential for most species however, it greatly increases the strike rate. Increasing your success Some of the more difficult cuttings can become easy with preplanning. The best cuttings are those that are taken from the junction of 1 year old and two year old wood as this area contains a large number of dormant buds and these supply hormones essential to the rooting process. Precallusing and etiolation (blanching) is also very effective and can be done easily by damaging the bark during summer and then binding it with black electricians tape in a process very similar to aerial layering but without the packing material. Rooting hormone can also be applied during this operation to help callus form. A the primary cause of cutting failure in spring is when the top of the cutting breaks bud and draws moisture out of the cutting before the root system has had sufficient time to grow and supply the top with moisture. This may be overcome by using a cold frame kept at a high humidity during the critical period in early spring when the buds are breaking. Another technique is to bury cuttings upside down so that the root end receives early spring warmth first and can callus sufficiently before the cuttings are dug up and the tops then exposed to the spring warmth to break bud. Apricots, Nectarines, Plums and Peaches These trees range from easy to difficult and it is impossible to draw conclusions across the board except to say that more cultivars than not strike well. For instance Redhaven peach will strike at rates of more than 90% whereas Elberta peach are around 20%. Santa Rosa plum are very good at more than 90% whereas shiro (another Japanese plum) is around 50%. While these percentages would be frowned on in commercial production they are adequate for home propagation. Better results are had if cuttings are taken shortly after leaf drop in autumn. Apple, Cherry, Loquat and Pear Mature fruiting varieties of cherry, apple, pear and loquat are very difficult to strike from hardwood cuttings. Rootstock apple, cherry and quince that develop root primordia can strike easily. Cherries strike better if taken shortly after leaf drop in autumn. Apple strike better when taken in late winter or very early spring. Aerial layering is a better option with cherry and apple and the formation of root primordia from this process greatly increases the chance of striking. Quince Quince (excepting Mammoth cv) strike easily from cuttings taken anytime after leaf drop. Gingko and Persimmon Gingko and persimmon are almost impossible to strike from cuttings. However, gingko are not impossible from soft wood cuttings. Mulberry Mulberries strike very easily. However, their buds are very susceptible to frost damage and cuttings must be kept above freezing once removed from the trees. Two to four weeks before bud break in late winter is best. Grapes and figs Figs strike very easily. Grapes also strike very easily from 3 node cuttings. However, both of these plants are notorious for breaking bud well in advance of their root system and are liable to dry out. A little care in this area will ensure very consistent results from cuttings. They may be taken anytime after leaf fall.
Rootstock suckers (An example) It is always good advice to remove rootstock suckers from fruit trees as they can eventually overpower the graft. But why waste them, these suckers provide valuable material for propagation as they are very vigorous, root and graft easily and can provide material for hardwood cuttings. Employing a mix of the techniques mentioned above gardeners can easily grow large trees that are ready for field planting within a year. The life of a rootstock sucker In a healthy tree, most suckers arise in the spring as latent buds on the rootstock burst. Being part of the original tree they grow rapidly and can easily reach 2 cm in diameter and 3 meters in height by the following autumn. Suckers can also burst periodically throughout the growing season and these can be retained until the following year if they don’t have enough time to make a good growth before winter. During the growing season well-managed trees have two periods of growth. These periods coincide with the cooler temperatures experienced in spring and late summer/early autumn. It is these periods of growth that are important to managing suckers as they coincide with spring/early summer grafting and late season forcing of the root system. Techniques Grafting Spring and early summer grafting when the bark is slipping may be accomplished using any familiar method. But the whip and tongue graft(WTG) with dormant scions collected in late winter is superior, as a scion with well spaced buds will give a good start to scaffold branches. The WTG may also be done at leaf bud break for second season suckers that were left over winter. Hardwood cuttings should be taken prior to bud break if WTG is to be used. Mounding or Aerial layering Suckers may arise from below ground and often form a rootsystem or root initials without any help. But they may also arise from the trunk. No matter the origin of the sucker the techniques are the same and are aimed at forcing the formation of roots by mounding or aerial layering. The easiest way to do this on a root sucker is to place a pot, with the bottom cut out, over the sucker. If the sucker arrises from the trunk a heavy gauge plastic bag (i.e. a Ziploc bag) is used with the corner cut out so the branch can be threaded through while still young. The trunk is purposefully damaged with a fingernail or slashed with a knife to encourage it to callus and it is covered with good moisture retentive compost or coir (milled coconut fibre). It is critical that the compost stays moist for the summer as this encourages the formation of callus and root initials.
A root sucker showing the root system developing after being girdled and layered with sawdust and compost In mid summer after the graft has taken the sucker is checked for the formation of root initials. Some rootstocks like ‘M’ series apples and ‘colt’ cherries root easily during this time. However, others (ie plums) need a little more encouragement. If no roots are observed by midsummer, the sucker must be girdled with wire (rooting hormone at this stage is beneficial, but is not essential). The wire should be firmly applied but not put on too tightly. The branch will recommence growth in late summer and as it expands, the wire will slowly strangle it. This forces the sucker to put out roots. It is critical that the compost be well watered during this stage, as the sucker has to increasingly rely on a very small root system for support. If the sucker displays excessive wilting (ie wilting has not recovered overnight) it may be necessary to remove the wire or prune it back. But if it looses its leaves and goes into dormancy a little early then this is normal. When the sucker has lost its leaves and is dormant it may be removed from the parent plant. Heavily prune the sucker to shape before removing it. If the stem was girdled with wire, the branch will usually snap very easily at this point.
A wire demonstrating girdling of a sucker, the developing root system and root primordia
Hardwood cuttings It is necessary to heavily prune suckers to balance the small root system with the top of the tree. Consequently, there is often a large amount of cutting material left over from the sucker’s ungrafted branches. Rootstocks are selected for their rooting ability and there is no need to waste the off-cuts as they will root and make good trees. The cuttings are taken and treated as detailed above. Garbage bags half filled with damp coir are excellent for callusing cuttings on a heat mat as they can be sealed to prevent the cutting drying out. It is important to leave a small hole in the top to allow condensation to escape. Once callused the whole bag can be sealed loosely and moved to a cool shady area until spring. Alternatively, a tall polystyrene broccoli box filled with coir and a glass cover is perfect for small cuttings. The box is left in a cold shady spot until the cuttings break leaf in spring.
The finished bare root tree Starting an orchard on the cheap Street trees and garden escapes are an overlooked resource for sourcing rootstock or even scion material if the fruit is good enough. They are also good for grafting good varieties into. Two very good trees for this purpose are the ornamental double flowered peach and the myrobalan or cherry plum. Both trees strike very easily from hardwood cuttings and the peach make a good rootstock for almonds, peaches and nectarines while the cherry plum makes a good rootstock for most plums and apricots.
A typical example of a cherry plum street tree with an overgrown rootstock. This is a cherry plum cv “nigra” on top of another cherry plum seedling rootstock. Both the purple leaved cultivar and the seedling are good for cuttings. Seedlings are often found growing under established trees and can make a quick contribution to the collection when dormant. They may also be grafted in situ and then collected in winter. The possibilities are endless!
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A well written article Karl,
A well written article Karl, and some very useful techniques that would apply well to other areas of plant propogation.
Thanks! Jan
"Be a light ...not a
"Be a light ...not a judge"
Wow ... Karl Thankyou for that ...I have taken notes in my garden journal.Great work.
Thanks for making the effort
Karl, this is a terrific article. Thanks so much for putting in the time and effort it took. It will be an invaluable reference for so many including moi.
What a wonderful resource
"You're a garden bully!"- Gimpy Cat
I'll definitely be using this info in the future. Outstanding!
Propogating deciduous fruit trees etc
This is a great article around Australian plants and reflects Australian seasons, it is great to have Australian specific planting information as so much gardening information on the internet is based on the Northern Hemisphere.
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