Flower Seeds That Need Light to Germinate

Which flower seeds need light to germinate?

Growing at the wrong time of year could be fatal to sensitive seedlings, so mother nature ensures they don’t grow until the right conditions are met. Some seeds need a period of darkness before they emerge, while other seedlings need light to germinate. Seeds contain enough food in order to feed the embryonic plant during germination. Once the newly emerged seedling reaches the light, photosynthesis takes over.

As a rule, small seeds need light to germinate as the seed doesn’t contain enough nutrients to sustain the emerging seedling long. Therefore, it is critical that the seedling reaches a light source as soon as it emerges from the shell.

When sowing seeds on the surface, ensure the soil is already moist and press lightly to prevent the seeds from being blown away.

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Scarification, Stratification and Soaking Seeds

Pre-treating seeds

Many seeds require pre-treatment before they are sowed. The three most common treatments are scarification, stratification and soaking. These treatments mimic the type of exposure seeds would experience in the wild.

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Flower Seed Sowing Guide

Flower seed sowing guide

The guide below compliments our flower seed sowing guide, with additional information on height, sun exposure, bloom time and toxicity to cats, dogs and people.

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Herb and Vegetable Seed Sowing Guide

Herb and vegetable sowing guide

Seeds require the right conditions or they will fail to germinate or germinate at a greatly reduced rate. Several factors trigger germination including soil temperature, moisture, soaking, stratification or scarification. 

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Flower Seed Sowing Guide

Flower seed sowing guide

Seeds require the right conditions or they will fail to germinate. Germination is triggered by soil temperature, soil depth, moisture and some seeds require stratification which is a period of chilling prior to sowing. This table is a quick and easy guide to sowing flower seeds.

Some seeds require sunlight to germinate, which has been listed as ‘surface’. Sprinkle the seeds on the surface, but gently push them down so that they don’t disperse in the wind. When sowing seeds that require a light covering of soil, add some soil or potting mix to an old kitchen sieve and gently sprinkle over the seeds.

Related: Flower height, position and bloom time

Many seedlings are frost-tender, and should only be planted once the risk of frost has passed, which is generally past Easter in the Northern Hemisphere. For those of us in warmer climates such as Australia, we can sow seeds much earlier.

Stratification refers to a period of cold that breaks dormancy. Gardeners can either sow in autumn so they will undergo stratification in the environment, or place seeds in a refrigerator and sow in spring. For those of us in a warmer climate, it is best to stratify in the refrigerator and plant in spring.

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Which Seeds Need Light to Germinate?

Which seeds need light to germinate?

There are a number of factors that trigger seeds to germinate just at the right time to enhance their survival. All seeds need moisture and oxygen to germinate, and the preferred soil temperature varies from plant to plant. In addition, some seeds need cold stratification, scarification, darkness or light. If these factors are not in place, germination will not occur, or if it does, it will be lower than expected.

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Optimal Soil Temperature For Flower Seed Germination

Optimal soil temperature for flower seed germination

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 – 2165 – 70No
African daisy (Osteospermum spp.)21 – 2470 – 75No
Alyssum (Lobularia maritima)12 – 2355 – 75No
Amethist flower (Browallia spp.)18 – 2165 – 70No
Aster (Aster spp.)18 – 2365 – 75No
Baby’s breath (Gypsophila spp.)15 – 1860 – 65No
Balloon flower (Platycodon grandiflorus)16 – 2060 – 68No
Bear’s breeches (Acanthus mollis)18 – 2165 – 70No
Bee balm (Monarda didyma)16 – 2160 – 70No
Begonia (Begonia spp.)18 – 2165 – 70No
Bellflower (Campanula spp.)21 – 2370 – 75Yes
Bells-of-Ireland (Moluccella laevis)13 – 1855 – 64Yes
Black-eyed Susan (Rudbeckia hirta)18 – 2165 – 70Yes
Bleeding heart (Dicentra spectabilis)4 – 1240 – 55Yes
Boltonia (Boltonia spp.)18 – 2165 – 70No
Borage (Borago officinalis)18 – 2965 – 85No
Bugle flower (Ajuga spp.)10 – 1550 – 60No
Bugloss (Anchusa capensis)18 – 2165 – 70No
Butter daisy (Melampodium
paludosum
)
18 – 2165 – 70No
Butterfly flower (Schizanthus spp.)18 – 2265 – 71No
Butterfly weed (Asclepias tuberosa)18 – 2465 – 75Yes
Calendula (Calendula officinalis)18 – 2165 – 70No
Californian poppy (Eschscholzia californica)12 – 2155 – 70No
Candytuft (Iberis spp.)23 – 2975 – 85No
Canterbury bells (Campanula medium)18 – 2165 – 70Yes
Cape jewels (Nemesia strumosa)13 – 1855 – 65No
Carnation (Dianthus spp.)15 – 2160 – 70No
Catnip/catmint (Nepeta spp.)18 – 2165 – 70No
Chamomile (Matricaria chamomilla)18 – 2165 – 70Yes
Chilean bellflower (Nolana paradoxa)20 – 2268 – 72No
Chinese aster (Callistephus chinensis)20 – 2368 – 73No
Chinese forget-me-not (Cynoglossum amabile)18 – 2065 – 68No
Chinese lantern (Physalis alkekengi)16 – 2160 – 70No
Chrysanthemum (Chrysanthemum spp.)18 – 2365 – 75No
Clematis (Clematis spp.)20 – 2268 – 73Yes
Cliquefoil (Potentilla spp.)19-2167-70No
Cohosh (Cimicifuga spp.)18 – 2165 – 70No
Columbine (Aquilegia spp.)10 – 1250 – 55Yes
Common rockrose (Helianthemum nummularium)21 – 2470 – 75No
Common sneezeweed (Helenium autumnale)19 – 2265 – 73No
Coral bell (Heuchera spp.)18 – 2165 – 70No
Corncockle (Agrostemma githago)15 – 2160 – 70No
Cornflower (Centaurea cyanus)15 – 2160 – 70No
Cosmos (Cosmos bipinnatus)21 – 2570 – 77No
Cup and saucer vine (Cobaea scandens)21 – 2370 – 75No
Cupflower (Nierembergia spp.)21 – 2370 – 75No
Cupid’s bow (Achimenes spp.)21 – 2370 – 75No
Cupid’s dart (Catananche caerulea)20 – 2368 – 75No
Cyclamen (Cyclamen spp.)18 – 2065 – 68No
Dahlberg daisy (Dyssodia tenuiloba)18 – 2165 – 70No
Dahlia (Dahlia spp.)21 – 2370 – 75No
Delphinium (Delphinium elatum)15 – 2059 – 68Yes
Echinacea (Echinacea spp.)18 – 2165 – 70Yes
Edeiweiss (Leontopodium alpinum)18 – 2165 – 70Yes
English daisy (Bellis perennis)18 – 2165 – 70No
Evening primrose (Oenothera spp.)21 – 2670 – 80No
Everlasting (Helichrysum bracteatum)21 – 2470 – 75No
False sunflower (Heliopsis spp.)21 – 2370 – 73No
Fan flower (Scaevola aemula)20 – 2268 – 71No
Firecracker flower (Crossandra infundibuliformis)21 – 2770 – 80No
Flax (Linum usitatissimum)18 – 2165 – 70No
Fleabane (Erigeron spp.)18 – 2165 – 70No
Floss flower (Ageratum houstonianum)24 – 2975 – 85No
Forget-me-not (Myosotis spp.)18 – 2165 – 70No
Foxglove (Digitalis spp.)15 – 1860 – 65No
Garden heliotrope (Heliotropium spp.)18 – 2165 – 70No
Gay feather (Liatris spp.)18 – 2165 – 70Yes
Gazania (Gazania spp.)15 – 1860 – 65No
Gerbera (Gerbera spp.)21 – 2370 – 73No
Geum (Geum spp.)18 – 2165 – 70No
Globeflower (Trollius spp.)18 – 2165 – 70Yes
Glory of the snow (Chionodoxa spp.)10 – 1550 – 59Yes
Gloxinia (Sinningia speciosa)19 – 2166 – 70No
Goldencup (Hunnemannia fumariifolia)19 – 2166 – 70No
Goldenrod (Solidago spp.)20 – 2268 – 71Yes
Goldentuft (Aurinia saxatilis)15 – 2159 – 70No
Hellebore (Helleborus spp.)18 – 2165 – 70Yes
Hibiscus (Hibiscus spp.)21 – 2670 – 75No
Hollyhock (Alcea rosea)15 – 2160 – 70Yes
Iceland poppy (Papaver nudicaule)18 – 2465 – 75Yes
Impatiens (Impatiens spp.)21 – 2370 – 73No
Jacob’s ladder (Polemonium spp.)18 – 2165 – 70No
Laceflower (Trachymene coerulea)18 – 2165 – 70No
Ladys purse (Calceolaria spp.)21 – 2370 – 73No
Larkspur (Consolida ambigua)10 – 1250 – 55Yes
Lavender (Lavandula spp.)18 – 2165 – 70No
Leopard plant (Ligularia spp.)18 – 2165 – 70No
Linaria (Linaria spp.)12 – 1855 – 65Yes
Lisianthus (Eustoma grandiflorum)22 – 2372 – 73No
Livingstone daisy (Dorotheanthus
bellidiformis
)
18 – 2465 – 78No
Lobelia (Lobelia spp.)18 – 2365 – 73No
Love-lies-bleeding (Amaranthus caudatus)20 – 2868 – 82No
Lupine (Lupinus spp.)12 – 2155 – 70Yes
Madagascar periwinkle (Catharanthus
roseus
)
24 – 2775 – 80No
Marigold (Tagetes spp.)21 – 2370 – 73No
Marshmallow plant (Althaea officinalis)15 – 2160 – 70Yes
Mexican creeping zinnia (Sanvitali procumbens)18 – 2165 – 70No
Mignonette (Reseda odorata)12 – 1453 – 57No
Monkey flowers (Mimulus spp.)15 – 2160 – 70No
Monk’s hood (Aconitum spp.)12 – 1555 – 60Yes
Morning glory (Convolvulus spp.)
20 – 2168 – 70No
Nasturtium (Tropaeolum majus)15 – 1860 – 65No
Nemesia (Nemesia spp.)12 – 1855 – 65No
Nemophila (Nemophila spp.)12 – 1555 – 60No
Nigella (Nigella damascena)15 – 1860 – 65No
Obedient plant (Physostegia virginiana)18 – 2165 – 70No
Pansy (Viola tricolor var. hortensis)15 – 2360 – 73No
Pearly everlasting (Anaphalis margaritacea)18 – 2165 – 70No
Persian violet (Exacum affine)21 – 2470 – 78No
Petunia (Petunia spp.)18 – 2365 – 73No
Phlox (Phlox spp.)15 – 1860 – 65No
Poppy (Papaver spp.)15 – 2060 – 68Yes
Portulaca (Portulaca spp.)21 – 2670 – 80No
Pride of Madeira (Echium candicans)15 – 2060 – 68No
Primrose (Primula spp.)15 – 1860 – 65Yes
Purple rock cress (Aubrieta deltoidea)18 – 2165 – 70No
Queen Anne’s lace (Daucus carota)16 – 1860 – 65No
Rock cress (Arabis spp.)18 – 2165 – 70No
Rudbeckia (Rudbeckia spp.)21 – 2370 – 73No
Salvia (Salvia officinalis)21 – 2370 – 73No
Satin flower (Clarkia amoena)21 – 2370 – 73No
Shooting star (Dodecatheon meadia)18 – 2165 – 70Yes
Sea holly (Eryngium spp.)18 – 2365 – 73Yes
Shasta daisy (Leucanthemum x superbum)18 – 2165 – 70No
Snapdragon (Antirrhinum majus)18 – 2365 – 73Yes
Snow-in-summer (Cerastium tomentosum)18 – 2165 – 70No
Speedwell (Veronica spp.)18 – 2465 – 75No
Spider flower (Cleome spinosa)21 – 2370 – 73Yes
Statice (Limonium sinuatum)15 – 2060 – 68No
Stock (Matthiola incana)15 – 1860 – 65No
Stoke’s aster (Stokesia laevis)21 – 2470 – 75No
Sunflower (Helianthus spp.)21 – 2370 – 73No
Swan river daisy (Brachyscome iberidifolia)21 – 2470 – 78No
Sweet pea (Lathyrus odoratus)12 – 1855 – 65No
Trumpet flower (Incarvillea spp.)18 – 2165 – 70No
Tweedia (Oxypetalum coeruleum)18 – 2165 – 70No
Twinspur (Diascia spp.)15 – 1860 – 65No
Verbena (Verbena spp.)18 – 2365 – 73No
Viola (Viola spp.)18 – 2365 – 73No
Virginian stock (Malcolmia maritima)18 – 2365 – 73No
Wallflower (Erysimum cheiri, syn. Cheiranthus cheiri)15 – 1860 – 65No
Wild indigo (Baptisia spp.)18 – 2165 – 70No
Wishbone flower (Torenia fournieri)21 – 2370 – 75No
Xeranthemum (Xeranthemum annuum)24-3575 – 95No
Yarrow (Achillea spp.)18 – 2165 – 70Yes
Yellow lotus (Nelumbo lutea)21 – 2470 – 78No
Zinnia (Zinnia spp.)21 – 2370 – 73No

Optimal soil temperature for flower germination PDF

Soil Temperature For Vegetable & Herb Seed Germination

Optimal temperature for seed germination

Soil temperature is one of the most important factors in seed germination. Too cold or too hot and the seeds may not germinate. Seeds are dormant, and germination occurs when outside factors are optimal for the plant’s survival. When the time is right, the seed germinates. Knowing the preferred soil temperature for common vegetables and herbs will increase the germination rate.

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