Growing a Sustainable Garden:
What Does a Seed Need?
Whether you're starting seeds indoors to transplant or planting them
directly in your garden, there are two simple things a seed needs to
successfully germinate and sprout. These are:
- warm soil temperatures, and
- moisture.
Light is not necessary! Remember, the seeds are beneath the soil surface.
Sustained, warm soil temperatures are critical. Both percentage of germination
and number of days to emergence are greatly affected by temperature changes.
Most vegetable seeds need a constant soil temperature between 68 and 86
degrees to germinate and sprout, with 77 degrees being optimal.
Percentage of Normal Vegetable Seedlings
Produced at Different Temperatures*
Numbers in ( ) are the days to seedling emergence. Number in red
is the optimal daytime soil temperature for maximum production
in the shortest time.
| Crops |
32ºF |
41ºF |
50ºF |
59ºF |
68ºF |
77ºF |
86ºF |
95ºF |
104ºF |
| Asparagus |
0 |
0 |
61(53) |
80(24) |
88(15) |
95(10) |
79(12) |
37(19) |
0 |
| Beans, lima |
0 |
0 |
1 |
52(31) |
82(18) |
90(7) |
88(7) |
2 |
0 |
| Beans, snap |
0 |
0 |
1 |
97(16) |
90(11) |
97(8) |
47(6) |
39(6) |
0 |
| Beets |
0 |
53(42) |
72(17) |
88(10) |
90(6) |
97(5) |
89(5) |
35(5) |
0 |
| Cabbage |
0 |
27 |
78(15) |
93(9) |
0(6) |
99(5) |
0(4) |
0 |
0 |
| Carrots |
0 |
48(51) |
93(17) |
95(10) |
96(7) |
96(6) |
95(6) |
74(9) |
0 |
| Cauliflower |
0 |
0 |
58(20) |
60(10) |
0(6) |
63(5) |
45(5) |
0 |
0 |
| Celery |
0 |
72(41) |
70(16) |
40(12) |
97(7) |
65 |
0 |
0 |
0 |
| Cucumber |
0 |
0 |
0 |
95(13) |
99(6) |
99(4) |
99(3) |
99(3) |
49 |
| Eggplant |
0 |
0 |
0 |
0 |
21(13) |
53(8) |
60(5) |
0 |
0 |
| Lettuce |
98(49) |
98(15) |
98(7) |
99(4) |
99(3) |
99(2) |
12(3) |
0 |
0 |
| Muskmelon |
0 |
0 |
0 |
0 |
38(8) |
94(4) |
90(3) |
0 |
0 |
| Okra |
0 |
0 |
0 |
74(27) |
89(17) |
92(13) |
88(7) |
85(6) |
35(7) |
| Onions |
90(136) |
98(31) |
98(13) |
98(7) |
99(5) |
97(4) |
91(4) |
73(13) |
2 |
| Parsley |
0 |
0 |
63(29) |
0(17) |
69(14) |
64(13) |
50(12) |
0 |
0 |
| Parsnips |
82(172) |
87(57) |
79(27) |
85(19) |
89(14) |
77(15) |
51(32) |
1 |
0 |
| Peas |
0 |
89(36) |
94(14) |
93(9) |
93(8) |
94(6) |
86(6) |
0 |
0 |
| Peppers |
0 |
0 |
1 |
70(25) |
96(13) |
98(8) |
95(8) |
70(9) |
0 |
| Radish |
0 |
42(29) |
76(11) |
97(6) |
95(4) |
97(4) |
95(3) |
0 |
0 |
| Spinach |
83(63) |
96(23) |
91(12) |
82(7) |
52(6) |
28(5) |
32(6) |
0 |
0 |
| Sweet Corn |
0 |
0 |
47(22) |
97(12) |
97(7) |
98(4) |
91(4) |
88(3) |
10 |
| Tomatoes |
0 |
0 |
82(43) |
98(14) |
98(8) |
97(6) |
83(6) |
46(9) |
0 |
| Turnips |
1 |
14 |
79(5) |
98(3) |
99(2) |
100(1) |
99(1) |
99(1) |
88(3) |
| Watermelon |
0 |
0 |
0 |
17 |
94(12) |
90(5) |
92(4) |
96(3) |
0 |
* The above data was taken from a report published in the mid-1980's.
Author, affiliation, and publisher are not known.
Source:http://tomclothier.hort.net/page11.html
Planting Seeds Directly into the Garden
If you plant seeds directly into the garden you'll get the
best results using
soil beds like the ones we've described
previously. They are level, slightly raised, and ridged
all around, which among other things improves drainage and allows the soil
to warm up faster.
A rule of thumb for planting depth is 2 ˝ times the width of the seed.
Many people plant seeds and cuttings deeper than needed and increase
the effort necessary for new plants to reach life-giving sunlight.
In the soil, space your plants according to their size at maturity.
Planting too close together is not only wasteful of seeds, but also
much more work in the long run because you have to thin out the
excess plants. In addition, your plants have to compete for scarce
light, water, and nutrients. And tearing out the neighbors
disturbs the roots of those plants which are left.
Here’s how to plant small seeds (such as carrots and lettuce) to
maximize your yield while minimizing work and waste:
- Determine how many plants you want to grow, and how many seeds you have.
You might want 600 to 800 carrots, but 25 lettuce plants may be more
than you can use unless you plan on selling some. A one ounce seed packet
contains 19,000 carrot seeds or 16,000 lettuce seeds, so you may not want
to plant the whole package!
- Figure how much space you’ll need for the plants you want. Eight hundred carrots
planted only 1” apart will more than fill both rows in a 30-long bed.
- Mix your seeds with clean sand in a ratio of 1 part seed to 100 parts sand.
A 1/4 cup measure is 24 teaspoons, so just a 1/4 teaspoon of carrot seed
and a 1/4 cup measure of sand is just about right to plant approximately
750 carrot seeds in one soil bed.
- Scratch a straight shallow furrow down the sides of your soil-bed near the ridges.
- Carefully distribute your seed/sand mix evenly for the entire pre-determined planting distance.
- Cover the seed/sand mix with 1/8th” of clean sand. Do NOT use the existing dirt, especially if it is clay soil.
- Water gently to avoid moving the seed. Rolling sprouting seed can easily kill it.
Once your seeds have sprouted, make sure that they have warm temperatures,
maximum light, and good drainage to prevent damping off and other problems.
Begin immediately to apply the
Mittleider Weekly Feed Mix as a side
dressing 4” from your plant stems, and water it in thoroughly.
Do this once each week until 3 weeks before maturity.
To assure good seed germination and strong seedlings in the shortest possible time,
be sure to either wait until your garden soil temperatures are in the optimum range
(use a thermometer!) or start your seeds indoors in flats where you can control
temperature and moisture. We'll discuss indoor seed starting next week.
Jim Kennard
Jim Kennard
is President of the
Food For Everyone
Foundation, a non-profit organization with the
mission of "Teaching the world to grow food one
family at a time". You'll find many free vegetable
gardening resources, including a gardening ebook,
greenhouse plans, automated watering plans, and
a free chapter from each of the great gardening
books and software CD's Jim offers, at the
website:
www.foodforeveryone.org
