Handbook of Plant and Crop Physiology

GERMINATION AND EMERGENCE 109

1. The list is limited to genera and species in temperate North America grown primarily for ornamental purposes. The following r

eferences were used for the compilation of the table: 35–40.

2. If seeds require light for germination, maintain adequate moisture around the seeds during the germination period by a mist s

ystem, by careful watering with a fine spray, by use of a plas-

tic cover over seed trays, or by watering from the bottom. Otherwise, cover the seed to a depth at least twice its size with ve

rmiculite or sowing medium to ensure that adequate moisture

is provided. Very small seeds are usually sown on top of the germinating medium and are not covered.

Caution

: plastic covers cause heat buildup, which if allowed to reach high levels,

could be detrimental to seeds.

3. Low temperature, such as that in a refrigerator, increases the longevity of most species of seed. Unless otherwise indicated,

store dry in the original sealed packet or in a tightly closed

plastic bag or sealed container. Silica gel or other hygroscopic substances may be added to resealed packages or container to k

eep humidity low.

4. Fall sowing of woody perennial seeds in outdoor beds, or in flats or containers kept outdoors during the winter, will satisfy

their chilling (cold stratification) requirement to germinate the

following spring. This practice may also replace a need for warm stratification or for scarification. Alternatviely, germinatio

n can be scheduled to occur at any time after chilling seeds in

a refrigerator.

5. Seeds with complex dormancy may require both warm and cold stratification in sequence. If sufficient heat is gained by unstra

tified seeds after a late summer or fall seeding to satisfy the

warm requirement, germination will occur the following spring. Otherwise, germination will occur the second spring.

6. Seeds must usually be removed from fleshy fruits. Mechanical devices such as a fruit press can be used to macerate the fruit.

Seeds can then be separated by flotation, screening, fer-

mentation, or other means. Nonviable seeds are light and usually float in water; viable seeds are heavier and sink.

Ulmus americanaU. parvifolia

ElmUlmaceae

Viburnum acerifoliumV. dentatumV. lantanaV. lentagoV. opulus

ViburnumCaprifoliaceae

DTDT DSDSDSDSDS

Mar.–JuneSept.–Oct.July–Oct.July–Oct.July–Oct.July–Oct.July–Oct.

15 years at



3 

C

and 3–4%moisturecontent

3 

years dry at1–5

C

3–910–12None5–9^5

2–32–3^312 2–4^3

Sow seeds with wings

attached.

Macerate fruits in water to

remove pulp.

See note 5.