Planting a vegetable garden has a variety of challenges. But how disappointing when the seeds are planted and nothing comes up! Here are primary reasons for poor seed germination.
1.
Planting depth – small seeded vegetables like carrots and onions can
easily be planted too deep. If planted too close to the surface, the seed can easily be washed away during
heavy rains. Consult the seed packet for proper planting depths.
2. Temperature
– some seed need the soil temperature to warm up before they will adequately
germinate, while other cool season vegetables like onions, germinate best in a
cool soil.
3.
Water - too little and seeds will not germinate or will dry up after
germination. With too much water, seeds and seedlings can die from lack
of oxygen or be overcome by
fungi. Even under normal moisture conditions, different
species of fungi and bacteria can cause seeds to rot. Seeds and
seedlings should always be kept moist, but the soil should not remain soaking
wet.
4. Soil pH - each
vegetable seed as well as other plants will have its range in which it will germinate best.
5.
Herbicide residues - may still be active in the soils causing poor
germination. A high fertilizer content
in the soil could also hamper germination.
6. Insects will often feed on seeds and young seedlings.
7. And finally, the seed itself! Poor seed germination can particularly be a problem in humid climates. Relative humidity influences the
moisture content of the seed. The higher the moisture content, the lower the germination
rate will be, especially, after one year.
As a general rule,
vegetable and flower seeds can be kept for one year without appreciable
decrease in germination. Storage, however, may be extended to 10 or more years
under proper conditions; seed moisture and temperature are the most important
factors. The drier the seeds, the longer they will store.
In humid climates such as Hawaii, storing vegetable
seeds in a dry, sealed glass container should keep most seeds viable for a
year. For longer storage, place seeds in a moisture-proof container and store
in the refrigerator.
Longevity of
vegetable seeds will also vary depending on the species. For example, collards, cucumber, endive,
radish and water cress produce some of the hard seeds, rated as lasting 5
years. Next come beets, cabbage, cauliflower, eggplant, kale, mustard, squash,
swiss chard, tomato, turnip, watermelon, rated at a 4 year longevity; asparagus,
beans, carrot, celery,
chinese cabbage, New Zealand spinach, pea, and spinach, at 3 years;
leek, sweet corn, okra and pepper are
rated at 2 years; and finally, the last group is rated at a mere
1 year longevity - lettuce, parsley, parsnip and onion.
Photo: Purdue University
