Growing Rare Fruit From Seed

John M. Riley

The information here was extracted with minor revisions from an article by John M. Riley that appeared in the 1981 CRFG Yearbook (vol. 13, 1981, pp.1-47). The full article contains important additional information on mechanisms of seed germination, propagation techniques, propagation media, container mixes and seed storage. See the back issue information for price and ordering information.

Seed Treatment Methods

Hot Water
This treatment consists of soaking the seed in hot water for a period of time. One procedure is to pour boiling water over the seed, using about four volumes of water to one volume of seed. The intent is a thermal shock which rapidly diminished to room temperature. Usually this is followed by moist cold storage. Most pathogens are destroyed at about 160° F (71° C). The treatment is a little tricky for home use, since most seed are killed at 178° F (81° C).
Sulfuric Acid Treatment
The acid attacks cellulose and is often recommended as a dramatic treatment for seed coat modification. For the home gardener, handling sulfuric acid may present some hazard.
Hydrogen Peroxide
This is commonly available in a 3% solution. It may be used in full strength for about 20 minute to disinfect seed and alter the seed coat. The peroxide may then be diluted in half with water and the seed soaked for up to 24 hours.
Sodium/Calcium Hypochlorite
This material is commonly available as ordinary laundry bleach. It effectively sterilizes and disinfects when used in a 10% solution. This can be prepared by added 1/4 cup bleach to 2 cups of water. Soak the seed for 20 minutes to sterilize and rinse thoroughly afterwards.
Alcohol and Other Solvents
Many volatile solvents, including grain alcohol have been mentioned as having an effect on seed germination. Quite possibly this results from softening waxy compounds in the seed coat which are not water soluble.
Gibberellin
Gibberellic acid promotes germination in many seeds. It also helps overcome the tendency for some seedling to become dwarfed and to grow slowly after the harsh treatment used to initiate germination. Seed may be soaked with concentration of 100 to 1,000 ppm for 24 hours.
Cytokinins
Natural growth hormones stimulate the germination of many kinds of seed by acting at the molecular level on biological processes. Many synthetic cytokinins are available from tissue culture supply houses, but since they must be kept at a low temperature to prevent decomposition, they are not available in garden supply centers. Soaking for three minutes in kinetin at concentration of 100 ppm has been recommended.
Ethylene
This gas occurs naturally in plants and has a number of biological effects, including the stimulation of seed germination. One of the chemicals available to gardener to generate ethylene is ethephon. Since gibberellins, cytokinins and ethylene are three dominant components in initiating germination, it is natural that they work best when applied together.
Potassium Nitrate
Many freshly harvested dormant seeds germinate better if soaked in a 0.2% potassium nitrate solution. Seeds should be soaked for no more than 24 hours and then rinsed well.
Thiourea
This has been used to stimulate germination of some dormant seeds, particularly those that do not germinate in darkness or at high temperatures. A water solution of 0.5 to 4% is recommended. Since thiourea is somewhat inhibitory to growth, the seeds should be soaked no longer than 24 hours and then rinsed well.
Vitamins
The most common vitamin supplement for plants is vitamin B1 (thiamine). Other vitamins of the B complex are also useful. Nicotinic acid (niacin) and ascorbic acid (vitamin C) have all been recommended.
Willow Tea
A tea made from willow bark contains a substance that enhances the actions of plant hormones and appears to stimulate germination. Soaking seed in willow tea for 24 to 48 hours is suggested.

Procedures

The table that follows summarizes specific information useful for growing rare fruit from seed. Rare fruits (mostly those tried in California) are listed by their botanical names. Common names can be connected to their botanical names through the CRFG Fruit List.

Storage Life, in months, (assuming proper treatment) is listed in column two. The storage type (next column) is categorized as follows:

WTM--WARM TROPICAL MOIST
Seed should be maintained above 70° F (21° C) and not allowed to dry out before planting.
TI--TROPICAL INTERMEDIATE
Seed should be dried to about 70% of harvest weight and stored a temperature of about 40° F (4° C).
TD--TEMPERATE DRY
Seed should be dried to below 50% of harvest weight and stored at room temperature or preferably 40° F (4° C).
CM--COOL MOIST
Store seed with sufficient moisture to prevent drying out at about 40° F (4° C).

Dormancy Breaker, column four, indicates any special treatment to break dormancy. In each case the seed can profit from a 24-hour soaking before planting.

SC--SCARIFICATION
Seeds are made permeable to water by sanding, filing or nicking the seed coat.
R--SEED COAT REMOVAL
Carefully crack or remove outer seed coating.
SK--PRESOAK
Soak seed 24 hours before planting.
MC--MOIST CHILLING
After soaking 24 hours, pack the seed with moist sterile material and store for 30 to 60 days at 40° F (4° C).
ST--STRATIFY
Soak seed 24 hours and store moist for one or more seasons in the natural environment. Do not let seed dry out.
WMS--WARM MOIST STORAGE
After soaking 24 hours, store above 70° F (21° C). Plant soon.
CW--ALTERNATE COLD/MOIST TREATMENT
Soak seed for 24 hours and subject to periods of 40° F (4° C). Cycle several times if necessary.

Germination Period, column five, lists the time lapse between seedbed planting and emergence. Time required to break dormancy is not included. Times vary with cultivation and seed condition.

Hardiness (deg. F and C), column six. Values are approximate and are mostly taken from books which include the tropics, Florida and California. In a given situation, plant size, previous environment, health and chill factor can alter the response to a given temperature. There may also be significant differences in variants of the same species. The hardiness values listed are probably optimistic by about 5° F (2° C) for tropical fruit tree seedlings or young plants.

General Comments. A number following a symbol indicates the days of treatment required. A plus (+) after a number means the value may be exceeded. A temperature in parenthesis following the germination period indicates the minimum temperature (°F, °C) required for germination. The information on germination time is approximate and based largely on John Riley's personal experience.
CHARACTERISTICS OF RARE FRUIT PROPAGATION FROM SEED
Botanical
name
Storage
life (mos.)
Storage
type
Dormancy
breaker
Germination
days
Hardiness
°F (°C)
Actinidia
     chinensis 12+ TD SC/CW 14-21 10 (-12)
     arguta 12+ TD SC/CW 14-21 -25 (-32)
     kolomikta 12+ TD SC/CW 14-21 -40 (-40)
Aegle
     marmelo 12+ TI SK/WMS 14-21 28 (-2)
Akebia
     quinata 24+ TD MC 14-21 25 (-4)
     trifoliata 24+ TD MC 14-21 25 (-4)
Amelanchier
     ainifoli 8 TD SC/MC 14-21 -50 (-45)
     canadensis 8 TD SC/MC 14-21 -30(-35)
     denticulatum 8 TD SC/MC 14-21 -10(-23)
Anacardium
     occidental 1 WTM SK 14-21 30 (-1)
Annona
     cherimola 24+ TD SK 14-21 26 (-3)
     purpurea 12+ TI SK 14-21 28 (-2)
     reticulata 12+ TI SK 14-21 28 (-2)
     squamosa 12+ TI SK 14-21 28 (-2)
Antidesma
     bunius 12+ TI SK 14-21 26 (-3)
     dallachyanum 12+ TI SK 14-21 26 (-3)
     platyphyllum 12+ TI SK 14-21 28 (-2)
Arbutus
     unedo 12-24 TD MC 30 15 (-10)
Artocarpus
     communis 1 WTM WMS 7-21 35 (3)
     integrifolia 1 WTM WMS 7-21 30 (-1)
     hypargyraeus 1 WTM WMS 7-21 30 (-1)
Asimina
     triloba 12+ CM SC/MC 30-90 -25 (-32)
Averrhoa
     bilimbi 6 TI SK 14-21 28 (-2)
     carambola 6 TI SK 14-21 28 (-2)
Billardia
     cymosa 24+ TD MC 14-21 0 (-12)
     scandens 24+ TD MC 14-21 0 (-12)
Blighia
     sapida 3 WTM WMS 7-21 30 (-1)
Carica
     goudotiana 24+ TD SK 14-30 28 (-2)
     monoica 24+ TD SK 14-30 28 (-2)
     papaya 24+ TD SK 14-30 30 (-1)
     pubescens 24+ TD SK 14-30 26 (-3)
     stipulata 24+ TD SK 14-30 28 (-2)
     toronchi 24+ TD SK 14-30 28 (-2)
Carissa
     carandas 12+ TI SK 16 24 (-5)
     edulis 12+ TI SK 16 26 (-3)
     macrocarpa 12+ TI SK 16 26 (-3)
Carya
     illinoiensis 36-48 TI MC 30 -10 (-23)
Casimiroa
     edulis 6 TI R/SK 14-21 24 (-5)
     tetrameria 6 TI R/SK 14-21 28 (-2)
Castanea
     dentata 8 CM MC 28 -10 (-23)
     pumila 8 CM MC 28 -10 (-23)
Ceratonia
     siliqua 60 TD SC 20-30 20 (-8)
Cereus
     peruvianus 36 TD light 3-14 26 (-3)
Chrysophyllum
     cainito 6 WTM WMS 14-21 28 (-2)
Citrus
     aurantifolia 12 TI SK 14-21 28 (-2)
     aurantium 12 TI SK 14-21 28 (-2)
     limon 12 TI SK 14-21 28 (-2)
     maxima 12 TI SK 14-21 28 (-2)
     mitis 12 TI SK 14-21 20 (-8)
     paradisi 12 TI SK 14-21 25 (-4)
     reticulata 12 TI SK 14-21 25 (-4)
     sinensis 12 TI SK 14-21 25 (-4)
Clausena
     lansium 12 TI SK 14-21 25 (-4)
Coccolaba
     uvifera 12 TD WMS 14-21 30 (-1)
Coffea
     arabica 6 CM WMS 14-21 28 (-2)
     liberica 6 CM WMS 14-21 28 (-2)
Cornus
     amonum 24+ TD CW 14-21 0 (-18)
     mas 24+ TD CW 14-21 0 (-18)
Corylus
     americana 12+ CM CW 10-30 -15 (-26)
     avellana 12+ CM CW 10-30 -15 (-26)
Crateagus
     aestivalis 24+ TD SC/MC 30-40 -15 (-26)
     pubescens 24+ TD SC/MC 30-40 -15 (-26)
Cudrania
     tricuspidata 36 TD SC/ST 14-21 -20 (-29)
Cydonia
     oblonga 8 CM MC 14-21 -15 (-26)
Cyphomandra
     betacea 24 TD SK 14-21 28 (-2)
Diospyros
     digyna 6 WTM SK/WMS 14-21 28 (-2)
     discolor 6 WTM SK/WMS 14-21 28 (-2)
     kaki 12+ TI SC/MC 14-21 0 (-18)
     virginiana 24-36 TD SC/MC 14-21 -10 (-23)
Dovyalis
     abyssinica 24+ TI SK 14-21 25 (-4)
     caffra 24+ TI SK 14-21 28 (-2)
     hebecarpa 24+ TI SK 14-21 28 (-2)
Elaeagnus
     multiflora 24+ TI SK/MC 14-21 -10 (-23)
     philippensis 12+ TI SK 14-21 25 (-4)
     pungaens 24+ TI SK/MC 14-21 0 (-18)
Eriobotrya
     japonica 8 days CM MC 14-21 12 (-11)
Eugenia
     aggregata 6 TI SK 14-21 20 (-8)
     brasilliensis 6 TI SK 14-21 28 (-2)
     luschnathiana 6 TI SK 14-21 28 (-2)
     uniflora 6 TI SK 14-21 28 (-2)
Euphoria
     longan 1 WTM WMS 16-30 24 (-4)
Feijoa
     sellowiana 24+ TI MC 14-21 14 (-10)
Feronia
     limonia 12 TI SK 14-21 28 (-2)
Ficus
     carica 24+ TI SK 14-21 25 (-4)
Flacourtia
     ramonchi 12+ TI SK 14-21 28 (-2)
Fortunella
     japonica 12 TI SK 14-21 10 (-12)
     margarita 12 TI SK 14-21 10 (-12)
Garcinia
     mangostana 1-2 WTM SK/WMS 14-21 40 (4)
     xanthochymus 2-4 WTM SK/WMS 14-21 28 (-2)
Gaultheria
     shallon 12 TD MC 30 0 (-18)
Gaylussacia
     frondosa 24+ TD CW 10-30 0 (-18)
     resinosa 24+ TD CW 10-30 0 (-18)
Gevuina
     avellana 6 CM WMS 14-21 10 (-12)
Harpyphyllum
     caffrum 24+ TI R 14-21 26 (-3)
Hibiscus
     sabariffa 36 TD SK 14-21 28 (-2)
Hovenia
     dulcis 24+ TD SC/MC 14-30 -10 (-23)
Inga
     paterno 6 TI SK 14-21 28 (-2)
Litchi
     chinensis 1 WTM WMS 16-30 28 (-2)
Macadamia
     integrifolia 24 TI SK 14-30 24 (-4)
     tetraphylla 24 TO SK 14-30 24 (-4)
Malphigia
     glabra 6 TI SK 14-21 28 (-2)
Mammea
     americana 2-4 WTM SK/WMS 14-21 28 (-2)
Mangiferum
     indica 2 WTM R/SK 14-21 28 (-2)
Manilkara
     zapota 24 TD SK 15-30 28 (-2)
Melicoccus
     bijugatus 3 TI SK 14-21 28 (-2)
Morus
     alba 24+ TI SC/ST 14-21 -20 (-29)
     nigra 24+ TI SC/ST 14-21 0 (-18)
     rubra 24+ TI SC/ST 14-21 -10 (-13)
Muntingia
     calibura 12+ TI SK/WMS 14-21 28 (-2)
Musa
     balbisiana 12 TI SK/WMS 14-21 28 (-2)
Myrciaria
     cauliflora 6 TI SK 14-21 24 (-4)
Myrtus
     communis 24+ TD MC 14-21 25 (-4)
Passiflora
     alata 3-6 TI SK 14-21 28 (-2)
     edulis 3-6 TI SK 14-21 25 (-4)
     laurifolia 3-6 TI SK 14-21 25 (-4)
     ligularis 3-6 TI SK 14-21 28 (-2)
     molissima 3-6 TI SK 14-21 25 (-4)
     quadrangularis 3-6 TI SK 14-21 32 (0)
Persea
     americana 4 WTM WMS 14-21 22-28 (-6, -2)
Pistachia
     vera 2-3 TI R/SK 14-21 10 (-12)
Pometia
     pinnata 6 WTM WMS 14-21 28 (-2)
Poncirus
     trifoliata 12-24 TI SK 14-21 0 (-18)
Pouteria
     campechiana 6 WTM WMS 14-21 30 (-1)
     sapota 6 WTM WMS 14-21 30 (-1)
     viride 6 WTM WMS 14-21 30 (-1)
Prunus
     salicifolia 24 TI SK 14-21 20 (-7)
Psidium
     cattleianum 12+ TI SK 14-21 25 (-4)
     guajava 12 TI SK 14-21 28 (-2)
Punica
     granatum 36 TI MC 14-30 12 (-11)
Rhodomyrtus
     tomentosa 12 TI SK 14-21 26 (-3)
Ribes
     hirtellum 48+ TD MC 30 -30 (-35
     nigrum 48+ TD MC 30 -30 (-35)
     rubrum 48+ TD MC 30 -30 (-35)
     sativum 48+ TD MC 30 -30 (-35)
     uva-crispa 48+ TD MC 30 -30 (-35)
Rollinia
     deliciosa -- TI SK 14-21 28 (-2)
Sambucus
     caerulea 24+ TI SC/MC 30 -20 (-28)
     canadensis 24+ TI SC/MC 30 -20 (-28)
     racemosa 24+ TI SC/MC 30 -20 (-28)
Sandoricum
     koetjape 36 TD SK 14-21 26 (-3)
Shepherdia
     argentea 42+ TD SC/MC 30-60 -20 (-28)
Simmondsia
     chinensis 12+ TD SK 5-7 (78&176; F, 26&176; C) 15 (-10)
Solanum
     quitoense 24 TD SK 14-21 28 (-2)
     topiru 24 TD SK 14-21 28 (-2)
Sorbus
     aucuparia 24 TD MC 10-30 -20 (-28)
     domestica 24 TD MC 10-30 -10 (-23)
     terminalis 24 TD MC 10-30 -10 (-23)
Synsepalum
     dulcificum 1 WTM WMS 7-21 30 (-1)
Syzygium
     aromaticum 2-6 TI SK 14-21 32 (0)
     cumini 2-6 TI SK 14-21 28 (-2)
     jamabos 2-6 TI SK 14-21 28 (-2)
     malaccense 2-6 TI SK 14-21 28 (-2)
     paniculatum 2-6 TI SK 14-21 28 (-2)
Tamarindus
     indica 6 TI SK 14-21 28 (-2)
Theobroma
     cacao 1 WTM SK 7-14 (80&176; F, 27&176; C) 30 (-1)
Ugni
     molinae 24+ TI SK 14-21 10 (-12)
Vaccinium
     angustifolium 120 TI MC 30 -20 (-28)
     ashei 120 TI MC 30 -10 (-23)
     corymbosum 120 TI MC 30 -20 (-28)
Vitis
     labrusca 24+ CM MC 20-30 -20 (-28)
     rotundifolia 24+ CM MC 20-30 -5 (-21)
     vinifera 24+ CM MC 20-30 -5 (-21)
Ziziphus
     jujuba 12-24 TD R/SK 14-21 -20 (-28)
     mauritiana 12-24 TD R/SK 14-21 20 (-7)


© Copyright 1981,1997, California Rare Fruit Growers, Inc.
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