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Department of Plant and Soil Science

Indoor Seed Sowing Dates                                                                                                                   
Dr. Leonard Perry
Extension Professor                                                                                         
 
Starting seedlings of annual flowers and vegetables indoors has several advantages:
--the fun of watching your own plants grow from seed, getting a jump on spring
--the ability to grow more unusual and different varieties than you often find in retail outlets
--saving money
--using washed and recycled containers from year's prior, helping the environment
--the ability, especially in northern climates, of getting a jump on the season, extending it by several weeks by planting more mature plants than sowing seeds directly
--starting seedlings that are difficulty to sow direct and have survive, especially slow-growing ones
 
Culture:
--Use a sowing mix for starting seeds, not garden soil.  Those that don’t transplant well should be sown in peat pots (indicated in table).
--Sow at a depth of about twice the diameter of the seed; very small seeds can be sprinkled on the surface and allowed to settle in when the container is gently tapped on the sides.
--Keep gently watered, as with a water breaker ("rose") on a watering can.  Don't allow to dry out, and don't keep too wet.  Be sure to use lukewarm water, especially in the north.
--Sow in individual cells, or in rows in a flat.  This way if a disease starts it wont spread too far before you can remove the affected plants and soil.  The main disease to watch for is "damping-off", often caused by seedlings staying too wet.  Seedlings rot at the base, toppling over quickly.
--Keep in bright light.  You may grow under fluorescent lamps for much of the seedling and young plant growth.  Use alternating cool and warm white tubes, in a couple of light fixtures side by side over flats.  Keep 4 to 6 inches above tops of plants.  Hanging fixtures on chains makes it easy to raise them as plants grow.  Keep lights on 14 to 16 hours a day, such as on a timer.  New thinner energy-efficient tubes are effective and save energy. 
--Most seedlings light bottom heat, as from seedling heating mats. 
--Once seedlings start developing leaves, lightly fertilize them, such as with 1/2 strength liquid fertilizer.  Be aware that many organic liquid fish or seaweed fertilizer may have an undesirable odor indoors.
 
 
Dates:
--The following weeks are approximate from time of sowing to planting outside, not merely germination times which is what is usually seen in catalogs and on seed packets.   Generally those taking more weeks to produce a plant require more days to germinate.  So if 6 weeks, and you want to plant outside the end of May, sow mid-April. Weeks may vary slightly depending on variety/cultivar, conditions, and location.
--Two weeks are often given for packs, the first being the minimum to sow indoors and have a plant suitable for planting outside, the second to have a plant almost or in bloom under ideal conditions (high light, warmth, as in a hobby greenhouse or sunroom).  If you will grow mainly under lights, or under average home conditions, it may be best to aim for the fewer weeks.  Seedlings grown too long indoors with improper balance of heat and light (too warm, too little light) often get spindly.
--Weeks are for sowing in a cell-pack.  If sowing in these or flats, to transplant into a 4-inch pot for growing further prior to planting outside, add 2 weeks.
--Generally these times are for growing seedlings around 65F air temperature. If growing colder add a week, if growing warmer subtract a week.  So if 8 weeks is listed, figure 9 weeks if growing at 55-60F, or 7 weeks if growing at 65-70F. 
--Light or darkness is sometime seen as needed for seeds to germinate, however generally sowing at the proper depth will give the correct light.
--Many vegetables often just sown outdoors are so marked (o).
--Ease refers to Easy, Moderately easy, or Difficult to grow from seeds.
--Temperature (temp.) is ideal from growing seedlings once germinated, W (warm, 65-75F) or C (cool, 55-65F).  If none given, aim for around 65-68F air temperature. Plants usually will grow at less than the ideal, just perhaps slower.
--Some seeds and plants may be poisonous to various degrees, harmful to toxic, if ingested with several so noted.  If unknown, don't ingest and keep from children.
--Most listed flowers are annuals or biennials.  For more perennials and their sowing needs see perrysperennials.info.

 

 

weeks

 

Flower

pack

pot

ease

temp.

needs, comments

Agastache

10

12

E

 

 

Ageratum

6-9

11

E

 

 

Agrostemma

8

10

E

 

poisonous

Alonsoa

10

12

M

 

 

Alternanthera

8

10

E

 

 

Alyssum (annual), sweet (Lobularia)

4-6

8

E

C

 

Amaranthus

3-4

6

E

 

 

Ammobium

10

12

E

 

 

Anagalis

10

12

M

 

 

Angelonia

8

10

E

 

 

Aquilegia, Columbine

8-12

14

E

 

prechill seeds prior to sowing, poisonous

Arctotis

6

8

E

 

 

Aster (annual)

6

8

E

 

alternating day/night temperatures help

Balsam (impatiens)

6

8

E

 

 

Begonia, wax

10-22

24

M

 

 

Bells of Ireland (Moluchella)

8

10

M

C

prechill, alternating day/night temperatures help

Berlandiera

7

9

M

 

 

Bidens

7

9

E

 

 

Brachyscome

6

8

M

 

Blooms 80 days from sowing

Browallia

6-12

14

M

 

 

Calandrina

7

9

M

 

 

Calendula

4

6

E

C

 

Callistephus (China aster)

6

8

E

 

 

Campanula

6-18

20

M

 

 

Canna

10

12

E

W

soak seeds overnight before sowing

Canterbury Bells

10

12

E

 

 

Carnation

10

12

E

C

 

Carpanthea

7-8

10

E

 

 

Castor Bean

2

4

E

W

often sown outdoors when warm, poisonous

Celosia

4-8

10

E

W

 

Centaurea (Bachelor’s button)

4

6

E

C

Sow in peat pots or direct seed

Cerinthe

10

12

E

 

 

Chaenarrhinum

14

16

E

 

 

Cladanthus

6

8

E

 

 

Clarkia

7

9

E

 

Sow in peat pots or direct seed

Cleome

4-8

10

E

W

 

Clianthus

10

12

D

 

 

Coleus (Solenostemon)

6-10

12

E

W

 

Convolvulus

4

6

E

 

poisonous, prior soaking aids

Coreopsis

6-7

9

E

 

 

Cornflower

4

6

E

 

 

Cosmidium

4

6

E

 

 

Cosmos

4

6

E

 

Easy to direct sow outdoors

Crepis

9

11

E

 

 

Cuphea

10

12

E

W

 

Cynoglossum (Chinese forget me not)

6

8

E

 

 

Dahlia

4-9

11

E

C

 

Dianthus

6-10

12

E

C

 

Diascia

8

10

E

 

 

Dicondra

6-10

12

E

 

 

Digitalis

8

10

E

C

poisonous

Dimorphotheca

4-8

10

E

 

seeds not long-lived

Dolichos

3

5

E

W

 

Dusty Miller

8-10

12

E

 

 

Echium

6

8

E

 

poisonous

Eschscholzia

7

9

M

 

Sow in peat pots or direct seed

Eustoma, Lisianthus

14-18

20

D

 

 

Felicia

7

9

M

C

 

Fuchsia

10

12

M

W

 

Gaillardia

4-8

10

E

 

 

Gaura

8-10

12

E

 

 

Gazania

10

12

E

C

 

Geranium (Pelargonium)

10

12

E

 

 

Gilia

7

9

M

 

 

Godetia

6

8

M

 

 

Gomphrena

6-7

9

E

W

 

Gypsophila

8

10

E

C

 

Helenium

10

12

E

 

alternating day/night temperatures help

Helianthus

2

4

E

 

 

Helichrysum

6-8

10

E

 

 

Heliotrope

10

12

M

 

 

Hesperis

4

6

E

 

 

Hollyhock

6

8

E

 

 

Ice Plant

8

10

M

 

 

Impatiens

8-10

12

E

 

 

Ipomopsis

8

10

M

 

 

Kochia

4

6

E

W

May sow in peat pots

Larkspur (Consolida)

6-8

10

E

C

Poisonous, sow in peat pots

Laurentia

7

9

M

 

 

Lavatera

6-8

10

E

 

 

Legousia

7

9

M

 

 

Leonotus

8

10

E

 

 

Limnanthes

10

12

E

 

 

Limonium

8-12

14

E

 

 

Linanthus

7

9

E

 

 

Linaria

10

12

E

 

alternating day/night temperatures help

Linum

8

10

E

 

poisonous

Lobelia

9-10

12

E

C

Poisonous, germinates slowly

Lupinus

8

10

E

 

soak seeds overnight before sowing, poisonous

Lychnis

8

10

E

 

 

Malcolmia

7

9

M

 

 

Malva

8

10

E

 

poisonous

Marigold, French

6

8

E

 

Easy to direct seed

Marigold, African/American

8

10

E

 

 

Melampodium

7-8

10

E

 

alternating day/night temperatures help

Millet, Ornamental

8

10

E

 

 

Mirabilis, Four O'Clock

4-6

8

E

 

poisonous

Morning Glory (Ipomoea)

2

4

E

W

poisonous

Myosotis

4

6

E

 

 

Nasturtium (Tropaeolum)

4

6

E

 

Sow in peat pot or direct seed

Nemesia

4-7

9

E

C

 

Nemophila

8

10

M

C

 

Nepeta

7

9

E

 

alternating day/night temperatures help

Nicotiana

6

8

E

 

poisonous

Nierembergia

10

12

M

 

 

Nigella

4-10

12

E

 

Sow in peat pots or direct seed

Nolana

10

12

M

 

 

Osteospermum

10

12

E

 

 

Oxypetalum

10

12

M

 

 

Pansy, Viola

14

16

E

C

 

Papaver (poppy)

6

8

M

 

Poisonous, direct seed as transplants poorly

Penstemon

7

9

M

 

alternating day/night temperatures help

Pentas

12

14

M

 

alternating day/night temperatures help

Pepper, Ornamental

6-10

12

E

 

 

Petunia

8-10

12

E

W

 

Phacelia

6

8

E

 

 

Phlox, annual

6-8

10

E

C

 

Portulaca

6

8

E

 

alternating day/night temperatures help

Reseda (Mignonette)

6

8

E

 

Sow in peat pots or direct seed

Rudbeckia

6-8

10

E

 

alternating day/night temperatures help

Salpiglossis

8-9

12

E

C

 

Salvia, scarlet

6-8

10

E

 

alternating day/night temperatures help

Salvia, mealycup

8-10

12

E

 

 

Sanvitalia

6

8

E

 

 

Scabiosa

4-8

10

E

C

 

Schizanthus

8-10

12

E

 

 

Silene

6

8

E

 

 

Snapdragon

6-10

12

E

C

 

Spaeralcea

8

10

D

 

 

Spilanthes

10

12

E

 

 

Steirodiscus

7

9

M

 

 

Stocks

6-8

10

E

C

 

Sunflower

2

4

E

 

 

Sweet Pea

4

6

E

 

sow in peat pots, poisonous, soak seeds prior

Sweet William

6

8

E

C

 

Talinum

6-10

12

E

 

 

Thunbergia

6-8

10

E

 

may sow in peat pots

Tithonia

6

8

E

 

 

Torenia

10-12

14

M

 

alternating day/night temperatures help

Tracelium

10

12

E

 

 

Trachymene

6-8

10

E

 

 

Verbascum

10

12

E

 

alternating day/night temperatures help

Verbena

10

12

M

W

 

Vinca, annual (Catharanthus)

10-12

14

E

W

poisonous

Wahlenbergia

7

9

E

 

 

Zinnia

4

6

E

W

Doubles may become single if transplanted

 

 

 

 

 

 

Vegetables, herbs

 

 

 

 

 

Artichoke

6-8

10

M

 

 

Basil

4-6

8

E

 

 

Beans (o)

2

4

E

W

sow in peat pots, outdoors when warm

Beets (o)

5

7

E

 

soak seeds overnight before sowing

Borage

2

4

E

 

sow in peat pots

Broccoli

5

7

E

 

 

Brussels Sprouts

5

7

E

 

 

Cabbage, Kale

5

7

E

C

 

Carrot (o)

5

7

E

 

sow outdoors

Cauliflower

5

7

E

 

 

Chives

5

7

E

E

 

Corn, Sweet (o)

2

4

E

 

sow outdoors when warm

Cucumber (o)

3

5

E

W

sow outdoors when warm

Dill (o)

7

9

E

 

 

Eggplant

7

9

E

W

 

Gourd, ornamental (o)

3

5

E

 

sow outdoors when warm

Lavender

10

12

E

 

 

Lettuce (o)

4

6

E

 

some vars. require light to germinate

Melons (o)

4

6

E

W

sow in peat pots, outdoors when warm

Onion

5

7

E

C

 

Oregano

5

7

E

 

 

Parsley (o)

8

10

E

 

 

Pea, sweet

2

4

E

 

generally not sown indoors

Pepper

7

9

E

 

 

Sage

4

6

E

 

 

Spinach

4

6

E

 

best sown outdoors

Squash (o)

2

4

E

 

sow in peat pots, outdoors when warm

Summer Savory

4

6

E

 

 

Sweet Marjoram

5

7

E

 

 

Swiss Chard

6

8

E

 

 

Thyme

5

7

E

 

 

Tomatoes

5-7

9

E

 

 


University of Vermont Extension and U.S. Department of Agriculture, cooperating, offer education and employment to everyone without regard to race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, and marital or familial status.  Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the United States Department of Agriculture. University of Vermont Extension, Burlington, Vermont.

Prepared 03/09

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