Seeds are in a dormant state until the right conditions occur which triggers the end of dormancy. There are a number of critical factors that determine when a seed will germinate including moisture, oxygen and the right soil temperature. Some seeds also require a period of cold, known as cold stratification. This mimics the normal winter a seed would usually experience before germinating once temperatures warm up in spring.
We recommend gardeners purchase a soil temperature thermometer to check soil temperature before sowing seeds. These are available from most nurseries or online.
Celsius |
Fahrenheit |
Stratification? |
|
| African daisy (Arctotis stoechadifolia) | 18 – 21 | 65 – 70 | No |
| African daisy (Osteospermum spp.) | 21 – 24 | 70 – 75 | No |
| Alyssum (Lobularia maritima) | 12 – 23 | 55 – 75 | No |
| Amethist flower (Browallia spp.) | 18 – 21 | 65 – 70 | No |
| Aster (Aster spp.) | 18 – 23 | 65 – 75 | No |
| Baby’s breath (Gypsophila spp.) | 15 – 18 | 60 – 65 | No |
| Balloon flower (Platycodon grandiflorus) | 16 – 20 | 60 – 68 | No |
| Bear’s breeches (Acanthus mollis) | 18 – 21 | 65 – 70 | No |
| Bee balm (Monarda didyma) | 16 – 21 | 60 – 70 | No |
| Begonia (Begonia spp.) | 18 – 21 | 65 – 70 | No |
| Bellflower (Campanula spp.) | 21 – 23 | 70 – 75 | Yes |
| Bells-of-Ireland (Moluccella laevis) | 13 – 18 | 55 – 64 | Yes |
| Black-eyed Susan (Rudbeckia hirta) | 18 – 21 | 65 – 70 | Yes |
| Bleeding heart (Dicentra spectabilis) | 4 – 12 | 40 – 55 | Yes |
| Boltonia (Boltonia spp.) | 18 – 21 | 65 – 70 | No |
| Borage (Borago officinalis) | 18 – 29 | 65 – 85 | No |
| Bugle flower (Ajuga spp.) | 10 – 15 | 50 – 60 | No |
| Bugloss (Anchusa capensis) | 18 – 21 | 65 – 70 | No |
| Butter daisy (Melampodium paludosum) |
18 – 21 | 65 – 70 | No |
| Butterfly flower (Schizanthus spp.) | 18 – 22 | 65 – 71 | No |
| Butterfly weed (Asclepias tuberosa) | 18 – 24 | 65 – 75 | Yes |
| Calendula (Calendula officinalis) | 18 – 21 | 65 – 70 | No |
| Californian poppy (Eschscholzia californica) | 12 – 21 | 55 – 70 | No |
| Candytuft (Iberis spp.) | 23 – 29 | 75 – 85 | No |
| Canterbury bells (Campanula medium) | 18 – 21 | 65 – 70 | Yes |
| Cape jewels (Nemesia strumosa) | 13 – 18 | 55 – 65 | No |
| Carnation (Dianthus spp.) | 15 – 21 | 60 – 70 | No |
| Catnip/catmint (Nepeta spp.) | 18 – 21 | 65 – 70 | No |
| Chamomile (Matricaria chamomilla) | 18 – 21 | 65 – 70 | Yes |
| Chilean bellflower (Nolana paradoxa) | 20 – 22 | 68 – 72 | No |
| Chinese aster (Callistephus chinensis) | 20 – 23 | 68 – 73 | No |
| Chinese forget-me-not (Cynoglossum amabile) | 18 – 20 | 65 – 68 | No |
| Chinese lantern (Physalis alkekengi) | 16 – 21 | 60 – 70 | No |
| Chrysanthemum (Chrysanthemum spp.) | 18 – 23 | 65 – 75 | No |
| Clematis (Clematis spp.) | 20 – 22 | 68 – 73 | Yes |
| Cliquefoil (Potentilla spp.) | 19-21 | 67-70 | No |
| Cohosh (Cimicifuga spp.) | 18 – 21 | 65 – 70 | No |
| Columbine (Aquilegia spp.) | 10 – 12 | 50 – 55 | Yes |
| Common rockrose (Helianthemum nummularium) | 21 – 24 | 70 – 75 | No |
| Common sneezeweed (Helenium autumnale) | 19 – 22 | 65 – 73 | No |
| Coral bell (Heuchera spp.) | 18 – 21 | 65 – 70 | No |
| Corncockle (Agrostemma githago) | 15 – 21 | 60 – 70 | No |
| Cornflower (Centaurea cyanus) | 15 – 21 | 60 – 70 | No |
| Cosmos (Cosmos bipinnatus) | 21 – 25 | 70 – 77 | No |
| Cup and saucer vine (Cobaea scandens) | 21 – 23 | 70 – 75 | No |
| Cupflower (Nierembergia spp.) | 21 – 23 | 70 – 75 | No |
| Cupid’s bow (Achimenes spp.) | 21 – 23 | 70 – 75 | No |
| Cupid’s dart (Catananche caerulea) | 20 – 23 | 68 – 75 | No |
| Cyclamen (Cyclamen spp.) | 18 – 20 | 65 – 68 | No |
| Dahlberg daisy (Dyssodia tenuiloba) | 18 – 21 | 65 – 70 | No |
| Dahlia (Dahlia spp.) | 21 – 23 | 70 – 75 | No |
| Delphinium (Delphinium elatum) | 15 – 20 | 59 – 68 | Yes |
| Echinacea (Echinacea spp.) | 18 – 21 | 65 – 70 | Yes |
| Edeiweiss (Leontopodium alpinum) | 18 – 21 | 65 – 70 | Yes |
| English daisy (Bellis perennis) | 18 – 21 | 65 – 70 | No |
| Evening primrose (Oenothera spp.) | 21 – 26 | 70 – 80 | No |
| Everlasting (Helichrysum bracteatum) | 21 – 24 | 70 – 75 | No |
| False sunflower (Heliopsis spp.) | 21 – 23 | 70 – 73 | No |
| Fan flower (Scaevola aemula) | 20 – 22 | 68 – 71 | No |
| Firecracker flower (Crossandra infundibuliformis) | 21 – 27 | 70 – 80 | No |
| Flax (Linum usitatissimum) | 18 – 21 | 65 – 70 | No |
| Fleabane (Erigeron spp.) | 18 – 21 | 65 – 70 | No |
| Floss flower (Ageratum houstonianum) | 24 – 29 | 75 – 85 | No |
| Forget-me-not (Myosotis spp.) | 18 – 21 | 65 – 70 | No |
| Foxglove (Digitalis spp.) | 15 – 18 | 60 – 65 | No |
| Garden heliotrope (Heliotropium spp.) | 18 – 21 | 65 – 70 | No |
| Gay feather (Liatris spp.) | 18 – 21 | 65 – 70 | Yes |
| Gazania (Gazania spp.) | 15 – 18 | 60 – 65 | No |
| Gerbera (Gerbera spp.) | 21 – 23 | 70 – 73 | No |
| Geum (Geum spp.) | 18 – 21 | 65 – 70 | No |
| Globeflower (Trollius spp.) | 18 – 21 | 65 – 70 | Yes |
| Glory of the snow (Chionodoxa spp.) | 10 – 15 | 50 – 59 | Yes |
| Gloxinia (Sinningia speciosa) | 19 – 21 | 66 – 70 | No |
| Goldencup (Hunnemannia fumariifolia) | 19 – 21 | 66 – 70 | No |
| Goldenrod (Solidago spp.) | 20 – 22 | 68 – 71 | Yes |
| Goldentuft (Aurinia saxatilis) | 15 – 21 | 59 – 70 | No |
| Hellebore (Helleborus spp.) | 18 – 21 | 65 – 70 | Yes |
| Hibiscus (Hibiscus spp.) | 21 – 26 | 70 – 75 | No |
| Hollyhock (Alcea rosea) | 15 – 21 | 60 – 70 | Yes |
| Iceland poppy (Papaver nudicaule) | 18 – 24 | 65 – 75 | Yes |
| Impatiens (Impatiens spp.) | 21 – 23 | 70 – 73 | No |
| Jacob’s ladder (Polemonium spp.) | 18 – 21 | 65 – 70 | No |
| Laceflower (Trachymene coerulea) | 18 – 21 | 65 – 70 | No |
| Ladys purse (Calceolaria spp.) | 21 – 23 | 70 – 73 | No |
| Larkspur (Consolida ambigua) | 10 – 12 | 50 – 55 | Yes |
| Lavender (Lavandula spp.) | 18 – 21 | 65 – 70 | No |
| Leopard plant (Ligularia spp.) | 18 – 21 | 65 – 70 | No |
| Linaria (Linaria spp.) | 12 – 18 | 55 – 65 | Yes |
| Lisianthus (Eustoma grandiflorum) | 22 – 23 | 72 – 73 | No |
| Livingstone daisy (Dorotheanthus bellidiformis) |
18 – 24 | 65 – 78 | No |
| Lobelia (Lobelia spp.) | 18 – 23 | 65 – 73 | No |
| Love-lies-bleeding (Amaranthus caudatus) | 20 – 28 | 68 – 82 | No |
| Lupine (Lupinus spp.) | 12 – 21 | 55 – 70 | Yes |
| Madagascar periwinkle (Catharanthus roseus) |
24 – 27 | 75 – 80 | No |
| Marigold (Tagetes spp.) | 21 – 23 | 70 – 73 | No |
| Marshmallow plant (Althaea officinalis) | 15 – 21 | 60 – 70 | Yes |
| Mexican creeping zinnia (Sanvitali procumbens) | 18 – 21 | 65 – 70 | No |
| Mignonette (Reseda odorata) | 12 – 14 | 53 – 57 | No |
| Monkey flowers (Mimulus spp.) | 15 – 21 | 60 – 70 | No |
| Monk’s hood (Aconitum spp.) | 12 – 15 | 55 – 60 | Yes |
| Morning glory (Convolvulus spp.) |
20 – 21 | 68 – 70 | No |
| Nasturtium (Tropaeolum majus) | 15 – 18 | 60 – 65 | No |
| Nemesia (Nemesia spp.) | 12 – 18 | 55 – 65 | No |
| Nemophila (Nemophila spp.) | 12 – 15 | 55 – 60 | No |
| Nigella (Nigella damascena) | 15 – 18 | 60 – 65 | No |
| Obedient plant (Physostegia virginiana) | 18 – 21 | 65 – 70 | No |
| Pansy (Viola tricolor var. hortensis) | 15 – 23 | 60 – 73 | No |
| Pearly everlasting (Anaphalis margaritacea) | 18 – 21 | 65 – 70 | No |
| Persian violet (Exacum affine) | 21 – 24 | 70 – 78 | No |
| Petunia (Petunia spp.) | 18 – 23 | 65 – 73 | No |
| Phlox (Phlox spp.) | 15 – 18 | 60 – 65 | No |
| Poppy (Papaver spp.) | 15 – 20 | 60 – 68 | Yes |
| Portulaca (Portulaca spp.) | 21 – 26 | 70 – 80 | No |
| Pride of Madeira (Echium candicans) | 15 – 20 | 60 – 68 | No |
| Primrose (Primula spp.) | 15 – 18 | 60 – 65 | Yes |
| Purple rock cress (Aubrieta deltoidea) | 18 – 21 | 65 – 70 | No |
| Queen Anne’s lace (Daucus carota) | 16 – 18 | 60 – 65 | No |
| Rock cress (Arabis spp.) | 18 – 21 | 65 – 70 | No |
| Rudbeckia (Rudbeckia spp.) | 21 – 23 | 70 – 73 | No |
| Salvia (Salvia officinalis) | 21 – 23 | 70 – 73 | No |
| Satin flower (Clarkia amoena) | 21 – 23 | 70 – 73 | No |
| Shooting star (Dodecatheon meadia) | 18 – 21 | 65 – 70 | Yes |
| Sea holly (Eryngium spp.) | 18 – 23 | 65 – 73 | Yes |
| Shasta daisy (Leucanthemum x superbum) | 18 – 21 | 65 – 70 | No |
| Snapdragon (Antirrhinum majus) | 18 – 23 | 65 – 73 | Yes |
| Snow-in-summer (Cerastium tomentosum) | 18 – 21 | 65 – 70 | No |
| Speedwell (Veronica spp.) | 18 – 24 | 65 – 75 | No |
| Spider flower (Cleome spinosa) | 21 – 23 | 70 – 73 | Yes |
| Statice (Limonium sinuatum) | 15 – 20 | 60 – 68 | No |
| Stock (Matthiola incana) | 15 – 18 | 60 – 65 | No |
| Stoke’s aster (Stokesia laevis) | 21 – 24 | 70 – 75 | No |
| Sunflower (Helianthus spp.) | 21 – 23 | 70 – 73 | No |
| Swan river daisy (Brachyscome iberidifolia) | 21 – 24 | 70 – 78 | No |
| Sweet pea (Lathyrus odoratus) | 12 – 18 | 55 – 65 | No |
| Trumpet flower (Incarvillea spp.) | 18 – 21 | 65 – 70 | No |
| Tweedia (Oxypetalum coeruleum) | 18 – 21 | 65 – 70 | No |
| Twinspur (Diascia spp.) | 15 – 18 | 60 – 65 | No |
| Verbena (Verbena spp.) | 18 – 23 | 65 – 73 | No |
| Viola (Viola spp.) | 18 – 23 | 65 – 73 | No |
| Virginian stock (Malcolmia maritima) | 18 – 23 | 65 – 73 | No |
| Wallflower (Erysimum cheiri, syn. Cheiranthus cheiri) | 15 – 18 | 60 – 65 | No |
| Wild indigo (Baptisia spp.) | 18 – 21 | 65 – 70 | No |
| Wishbone flower (Torenia fournieri) | 21 – 23 | 70 – 75 | No |
| Xeranthemum (Xeranthemum annuum) | 24-35 | 75 – 95 | No |
| Yarrow (Achillea spp.) | 18 – 21 | 65 – 70 | Yes |
| Yellow lotus (Nelumbo lutea) | 21 – 24 | 70 – 78 | No |
| Zinnia (Zinnia spp.) | 21 – 23 | 70 – 73 | No |
Optimal soil temperature for flower germination PDF
Julia is a writer and landscape consultant from Wollongong with a love of horticulture. She had been an avid gardener for over 30 years, collects rare variegated plants and is a home orchardist. Julia is passionate about learning and sharing her knowledge of plant propagation and plant toxicology. Whether it’s giving advice on landscape projects or sharing tips on growing, Julia enjoys helping people make their gardens flourish.
