sowing guides

Seed sowing guides. When to plant seeds, what depth and how long will it take for seedlings to emerge?

Flower Seeds That Need Light to Germinate

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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

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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

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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

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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

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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?

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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

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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 – 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

Soil Temperature For Vegetable & Herb Seed Germination

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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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