March 14, 2009

1 - Don't let seeds dry when they are germinating!

Yard and Garden March 14, 2009


How critical is it to give native plant seeds a lot of water to get them to germinate? I planted some seeds of native wildflowers, watered them once, and only a few came up.


The time during which a seed is germinating is a critical period for moisture. If the seed begins to germinate and dries out, it will die. Some plants can survive on a single irrigation if the soil holds enough moisture and natural rainfall comes when needed. In very sandy soils that do not hold much water, the seeds can dry quickly and die. A clay soil will hold more moisture and give the seedling a better chance to establish.

Some seeds native to desert regions have a "chemical rain gauge" in the seed coat or fruit covering around the seed. This chemical prevents germination while it is present, but is washed away if there is adequate moisture. The quantity of moisture to wash this chemical away is the amount of moisture that is sufficient to allow the seed to germinate and grow. Some seeds may have more of this inhibitor so that they require more moisture, and some have less so that they can germinate more quickly. Those that germinate quickly are counting on another precipitation or irrigation event to sustain them; those that have more inhibitor are prepared to grow if there is no new precipitation event in the near future. This chemical inhibition of germination is an insurance policy to insure that at least a few of the seeds will germinate at the right time.

Our common garden flowers and vegetables often do not have these inhibitors. They were bred out so that we could plant the seed and have uniform germination. Wildflower seeds may still exhibit germination spread over time because they may have these inhibitors. Knowing this helps you understand that consistent irrigation is necessary for many of the flowers and vegetables we plant. This even applies to many of our lawn grasses. Water your plants enough to keep the soil moist, but not soggy. This should result in uniform seed sprouting and a good stand of vegetable or flower plants in your garden.

There are other forms of dormancy that spread seed germination over time, but the chemical inhibitor found in some wildflower and plants native to dry environments is one that points out the need for adequate moisture during seed germination.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at, or at the Desert Blooms Facebook page.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!