Many species are dioecious in nature, meaning that male and female flowers occur on different plants, and fruits form only on female plants. Growing these species from seed is an ideal way of ensuring that a mixture of male and female plants is obtained; if possible, grow on at least 4 or 5 plants to give yourself a good chance of having at least one male. Excess male plants can always be weeded out once it becomes clear what sex the plants are.
Details given for seeds in the tables below have a code for the recommended seed treatment prior to sowing:
Recommended seed treatments
Stratification of seeds involves mixing the seed with a moist medium and keeping warm and/or cold for a certain time before sowing. We recommend mixing seeds with moist (not wet) silver sand, using 4 parts or more sand to one of seeds; the mix should be placed in a plastic bag which can be sealed and re-opened. Label the bag well! Warm stratification means keeping the seed/sand mix at about room temperature, 60-70°F or 15-21°C; cold means keeping the mix at about 40°F (5°C) – a domestic fridge is ideal for small quantities. When cold stratifying over winter, seed/sand mixes can be placed outside in a rodent/bird-proof container (eg. a plastic dustbin). Whenever stratifying seed, check every week or two to see if germination is starting. When it does you will see white roots start to emerge from seeds, and if this happens then the seeds should be sown immediately. If this isn’t possible, keep the mix at a temperature just above freezing until you can sow.
Scarification of seeds involves softening the hard seed coat in some way to allow water to be imbibed into the seed. The simplest way of achieving this is to give the seeds a hot water soak, putting them into water at about 190°F (88°C) and allowing them to stand for several hours while the water cools. Alternatively, the seeds can be physically rubbed, eg. between two sheets of fine sandpaper – take care not to rub too much.
Dewaxing – some seeds are covered in a layer of wax (notably Myrica species) which stops the seeds imbibing water and germinating. This must be removed before stratification or sowing – the best way to do this is to rub the seeds between two sheets of coarse sandpaper (do it for periods of a few seconds at a time, then check the seeds – you only want to get rid of the wax and not damage the seeds!)
Seeds which take a long time to germinate are best sown in seed trays or pots, and covered with sand rather than compost. Very small seeds should be sown on the surface of the compost and the tray/pot kept moist by enclosing it in a plastic bag. Finally, don’t give up if seeds don’t germinate, or only a few germinate, in the first year – many seeds spread out their germination over more than one year. If the seeds are large enough, you can check their viability by cutting one in half – the seed embryo inside should be white and solid, and not soft or watery.
After the description of each species, codes are given for the recommended treatment to promote good germination. (Note that using these treatments does not guarantee germination. Seed lots vary in their requirements and these are a general guide only.) The codes used are:
- ND Not dormant, sow in spring.
- SI Not dormant, but must be sown immediately.
- SC Scarify and sow in spring.
- CS Cold stratify. Followed by a number of weeks, eg CS 13 = cold stratify 13 weeks (3 months).
- WS Warm stratify. Followed by a number of weeks, eg WS 6 = warm stratify 6 weeks.
Warm stratification can sometimes be followed by cold stratification, eg. WS 13 + CS 13 means 13 weeks warm first then 13 weeks cold stratification.
Example: Assuming an intended sowing date of April 1st, then 4 weeks of stratification should start on 4th March, 6 weeks on 17th February, 8 weeks on 3rd February, 13 weeks on 1st January, 16 weeks on 10th December, 20 weeks on 12th November, 26 weeks on 1st October, etc. If you have trouble counting the weeks backwards there is a handy date calculator at http://www.timeanddate.com/date/dateadd.html
Species | Stratification details |
Abies amabilis | CS4 |
Abies balsamea | CS4 |
Abies grandis | CS4 |
Abies nobilis | CS4 |
Acanthopanax senticosus | CS26+WS13 |
Acanthus mollis | ND |
Acca sellowiana | ND |
Acer saccharum | CS13 |
Achillea millefolium | ND |
Actinidia arguta | CS13 |
Actinidia chinensis | CS4 |
Actinidia kolomikta | WS13+CS13 |
Agastache foeniculum | ND |
Agastache rugosa | ND |
Akebia quinata | CS4 |
Alchemilla mollis | CS4 |
Akebia trifoliata | CS4 |
Alliaria petiolata | ND |
Allium babingtonii | ND |
Allium moly | WS4+CS4 |
Allium neapolitanum | ND |
Allium carinatum pulchellum | ND |
Allium schoenoprasum | ND |
Allium tuberosum | ND |
Allium senescens | ND |
Allium sphaerocephalum | ND |
Allium ramosum | ND |
Allium fistulosum | ND |
Allium ursinum | CS13-17 |
Alnus cordata | CS8 |
Alnus glutinosa | CS8 |
Alnus incana | CS8 |
Alnus rubra | CS8 |
Alnus sinuata | CS8 |
Alnus viridis | CS8 |
Althaea officinalis | ND |
Amelanchier alnifolia | WS4+CS16 |
Amelanchier canadensis | CS20 |
Amelanchier lamarckii | WS4+CS16 |
Amorpha fruticosa | CS2 |
Angelica dahurica | ND |
Angelica archangelica | WS4+CS4 |
Anthriscus sylvestris | ND |
Anthyllis vulneraria | SC+CS8 |
Aquilegia vulgaris | CS13 |
Aralia chinensis | CS13 |
Arbutus unedo | ND |
Arctostaphylos uva-ursi | SC |
Aronia melanocarpa | CS13 |
Artemisia dracunculus | ND |
Artemisia vulgaris | ND |
Asclepias syriaca | ND |
Asclepias speciosa | ND |
Asclepias tuberosa | ND |
Asimina triloba | CS13 |
Asperula odorata | CS13 |
Astragalus glycyphyllos | SC |
Astragalus mongholicus | |
Atriplex canescens | ND |
Atriplex halimus | ND |
Barbarea vulgaris | CS8 |
Berberis buxifolia | CS20 |
Berberis darwinii | CS17 |
Berberis lycium | CS8 |
Berberis vulgaris | CS8 |
Berberis wilsonii | CS8 |
Beta vulgaris maritima | ND |
Betula lenta | CS4 |
Betula papyrifera | CS4 |
Broussonetia papyrifera | ND |
Betula pendula | CS4 |
Betula pubescens | CS4 |
Calendula officinalis | ND |
Calluna vulgaris | CS20 |
Caltha palustris | WS4+CS6 |
Bunias orientalis | ND |
Buxus sempervirens | CS26 |
Calamintha nepeta | ND |
Camassia quamash | ND |
Calycanthus floridus | CS13 |
Campanula latifolia | ND |
Campanula rapunculoides | ND |
Campanula rapunculus | ND |
Capsicum pubescens Hidalgo | ND |
Caragana arborescens | SC |
Ceanothus sanguineus | SC |
Cedrus atlantica | CS4 |
Celtis australis | CS13 |
Centranthus ruber | ND |
Cephalotaxus fortunei | CS13 |
Cephalotaxus harr.drup. | CS13 |
Ceratonia siliqua | SC |
Cercidiphyllum japonicum | ND |
Cercis canadensis | SC+CS8 |
Cercis occidentalis | ND |
Cercis siliquastrum | SC+CS8 |
Chaenomeles cathayensis | CS13 |
Chaenomeles japonica | CS13 |
Chamaemelum nobile | ND |
Cichorium intybus var.intybus | ND |
Clematis vitalba | CS12 |
Chenopodium bonus-henricus | ND |
Chimonanthus praecox | WS13+CS13 |
Cladrastis lutea | SC |
Claytonia sibirica | ND |
Colutea arborescens | SC |
Cornus canadensis | WS13+CS13 |
Cornus capitata | CS8 |
Cornus kousa chinensis | CS14 |
Cornus mas | CS23 |
Cornus officinalis | CS23 |
Coronilla emerus | SC |
Coronilla varia | SC |
Crambe cordifolia | ND |
Crataegus arnoldiana | CS13 |
Crataegus durobrivensis | CS13 |
Crataegus ellwangeriana | CS13 |
Crataegus mollis | CS13 |
Crataegus monogyna | WS13+CS26 |
Crataegus oxycantha | WS13+CS26 |
Crataegus tanacetifolia | CS13 |
Cryptotaenia japonica f.viridis | ND |
Cupressus macrocarpa | CS4 |
Cynara cardunculus | ND |
Cynara scolymus | ND |
Cytisus scoparius | SC |
Decaisnea fargesii | CS16 |
Diospyros kaki | ND |
Diospyros lotus | CS4 |
Diospyros virginiana | CS13 |
Diplotaxis tenuifolia | ND |
Drimys winterii | ND |
Duchesnea indica | ND |
Echinacea purpurea | ND |
Elaeagnus angustifolia | ND |
Elaeagnus multiflora | CS8 |
Elaeagnus umbellata | WS4+CS10 |
Ephedra nevadensis | ND |
Eupatorium perforatum | ND |
Filipendula ulmaria | CS13 |
Foeniculum vulgare | ND |
Fragaria vesca | CS4 |
Galium album | CS8 |
Galega officinalis | ND |
Galium verum | ND |
Eryngium campestre | ND |
Gaultheria shallon | CS17 |
Genista tinctoria | SC |
Gentiana lutea | WS4+CS4 |
Gleditsia triacanthos | SC |
Glycyrrhiza echinata | SC |
Glycyrrhiza glabra | SC |
Halesia carolina | CS13 |
Hamamelis virginiana | CS34 |
Herniaria glabra | ND |
Helianthus maximiliani | ND |
Hemerocallis minor | ND |
Hemerocallis lilioasphodelus | ND |
Hippophae rhamnoides | CS17 |
Hosta sieboldiana elegans | ND |
Hippophae salicifolia | CS4-8 |
Hovenia dulcis | SC |
Hypericum androsaemum | ND |
Ilex aquifolium | WS12+CS40+WS12 |
Hypericum perforatum | ND |
Juncus inflexus | ND |
Hyssopus officinalis | ND |
Hypericum calycinum | CS4 |
Juniperus communis | WS13+CS13 |
Juniperus virginiana | CS8 |
Koelreuteria paniculata | WS13+CS26 |
Larix decidua | CS4 |
Laburnum anagyroides | SC |
Lamium purpureum | WS4+CS6 |
Lespedeza bicolor | SC |
Lathyrus maritimus | SC |
Lathyrus pratensis | SC |
Lavandula angustifolia | ND |
Lavandula latifolia | ND |
Levisticum officinale | ND |
Leonurus cardiaca | ND |
Lindera benzoin | CS14 |
Liquidambar styraciflua | CS4 |
Liriodendron tulipifera | CS26 |
Lotus corniculatus | SC |
Lotus pedunculatus | SC |
Lupinus arboreus | SC |
Lupinus albus Dieta | ND |
Lupinus perennis | SC |
Lycium barbarum | ND |
Maackia amurensis | SC |
Maclura pomifera | CS4 |
Mahonia aquifolium | CS17 |
Mahonia nervosa | CS17 |
Malva alcea | ND |
Malva moschata | ND |
Malva verticillata Crispa | ND |
Malva sylvestris | ND |
Marrubium vulgare | ND |
Medicago lupulina | ND |
Melilotus officinalis | ND |
Mahonia repens | CS17 |
Mentha aquatica | ND |
Melissa officinalis | ND |
Mentha longifolia | ND |
Mentha suaveolens | ND |
Mentha pulegium | ND |
Morus alba | CS16 |
Metasequoia glyptostroboides | CS4 |
Mentha piperita | ND |
Mentha spicata | ND |
Micromeria thymifolia | ND |
Monarda citriodora | ND |
Monarda didyma | ND |
Monarda fistulosa | ND |
Morus alba tatarica | CS13 |
Morus nigra | CS16 |
Myrica californica | dewax+CS4 |
Myrica cerifera | dewax+CS8 |
Myrica pensylvanica | dewax+CS13 |
Myrrhis Odorata | CS20 |
Myrtus communis | ND |
Nasturtium officinale | ND |
Origanum vulgare | ND |
Oenothera biennis | ND |
Origanum majorana | ND |
Oxyria digyna | ND |
Onobrychis viciifolia | SC |
Parthenocissus quinquefolia | CS12 |
Passiflora caerulea | CS4 |
Paulownia tomentosa | ND |
Phellodendron amurense | CS4 |
Ostrya carpinifolia | WS13+CS13 |
Parthenocissus tricuspidata | CS12 |
Parthenium integrifolium | ND |
Passiflora edulis | ND |
Phormium colensoi | ND |
Phormium tenax | ND |
Phragmites australis | ND |
Physalis alkekengi | ND |
Phytolacca americana | ND |
Pimpinella saxifaga | ND |
Pinus armandii | CS13 |
Pinus cembra | WS13+CS13 |
Pinus nigra austriaca | CS4 |
Pinus nigra corsicana | CS4 |
Pinus pinaster | CS4 |
Pinus pumila | CS18 |
Pinus radiata | CS4 |
Pinus sylvestris | CS4 |
Plantago coronopus Minutina | ND |
Plantago lanceolata | ND |
Pinus koraiensis | CS13 |
Pinus pinea | CS0-4 |
Platanus acerifolia | CS4 |
Polemonium caeruleum | ND |
Polemonium reptans | ND |
Polygonatum multiflorum | WS4+CS6 |
Polygonatum odoratum | ND |
Poncirus trifoliata | ND |
Prunella vulgaris | ND |
Prunus cerasifera | WS4+CS20 |
Prunus mahaleb | WS3+CS26 |
Prunus lusitanica | CS20 |
Prunus serotina | WS3+CS26 |
Pseudotsuga menziesii | CS4 |
Pyrus communis | CS16 |
Pulmonaria officinale | CS8 |
Pycnanthemum pilosum | ND |
Rheum officinale | ND |
Rheum australe | ND |
Rheum palmatum | ND |
Rhus glabra | WS13+CS13 |
Rhus typhina | WS2+CS13 |
Robinia pseudoacacia | SC |
Rosa rubiginosa | WS13+CS26 |
Rosa rugosa | CS17 |
Salvia officinalis | ND |
Rosmarinus officinalis | ND |
Rumex acetosa Large leaved | ND |
Rumex sangineus var.sanguineus | ND |
Ruta graveolens | ND |
Ruscus aculeatus | CS8 |
Sambucus nigra | WS13+CS26 |
Sanguinaria canadensis | CS8 |
Sanicula europaea | CS8 |
Sanguisorba minor | ND |
Sanguisorba officinalis | ND |
Scirpus lacustris | ND |
Secale montanum x | ND |
Sambucus racemosa | WS13+CS26 |
Saponaria officinalis | WS4+CS4 |
Sassafras albidum | CS16 |
Schisandra chinensis | CS13 |
Sedum telephium | ND |
Sedum rupestre | ND |
Sequioa sempervirens | CS4 |
Sequioadendron giganteum | CS4 |
Sedum kamtschaticum | ND |
Shepherdia argentea | CS13 |
Silene vulgaris | ND |
Smilacina racemosa | WS8+CS8 |
Shepherdia canadensis | WS4+CS12 |
Smyrnium olusatrum | ND |
Solanum abutiloides | |
Sophora japonica | SC |
Solidago virgaurea | CS13 |
Sorbus aria | CS16 |
Sorbus aucuparia | CS16 |
Sorbus domestica | CS17 |
Sorbus intermedia | CS16 |
Sorbus torminalis | CS17 |
Spartium junceum | SC |
Staphylea pinnata | WS22+CS13 |
Symphytum officinale | ND |
Tanacetum vulgare | ND |
Tanacetum parthenium | ND |
Taxus baccata | WS20+CS50 |
Taxodium distichum | CS4 |
Thuja occidentalis | CS4 |
Thuja plicata | CS4 |
Thymus serpyllum | ND |
Tilia cordata | WS13+CS26 |
Thymus vulgaris | ND |
Tilia platyphyllos | WS26+CS26 |
Tilia tomentosa | WS26+CS26 |
Toona sinensis | CS8 |
Trifolium dubium | ND |
Trifolium hybridum | ND |
Trifolium pratense | ND |
Trifolium repens | ND |
Ulex europaeus | SC |
Tsuga heterophylla | CS4 |
Ulmus pumila | ND |
Ulmus glabra | ND |
Vaccinium myrtillus | CS16 |
Valeriana officinalis | ND |
Viburnum opulus | WS17+CS9 |
Viburnum trilobum | WS17+CS13 |
Viola odorata | ND |
Vicia sativa spp nigra | ND |
Vitex agnus-castus | ND |
Vicia sylvatica | ND |
Viola tricolor | ND |
Wisteria sinensis | SC |
Yucca baccata | SC |
Zanthoxylum alatum | CS17 |
Zanthoxylum schinifolium | CS13 |
Zizyphus jujube | Snip down central suture with secateurs+ND |