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Starting seedlings

Posted 12/28/2015

Odd as it may sound, it will not be long before we will want to start vegetable seedlings for spring planting. This is critical for plants like tomatoes, peppers and eggplant, whose seeds must be planted indoors around the end of February. They cannot go outdoors until nighttime temperatures are consistently above 50°F. Too often, it goes from cool to sizzling hot in southern Nevada. When this happens, it can injure those plants before their fruits have had the chance to expand completely. If they are not planted until there are about three or four sets of true leaves, they are very likely to survive and produce the fruits we want to obtain.

Cool weather plants, like spinach, kale, or lettuce may go directly into the garden, but when temperatures are too chilly, they can be started in peat pots so they are established before going into the ground. "Chilly" would be anytime it is less than 40°F. Very few seeds can germinate under those conditions.

Those who usually buy transplants may not be familiar with starting seeds, but it is an excellent way to expand your horticultural palette. Usually nurseries have a relatively limited range of varieties, but with seeds, the options are enormous. Why grow a head of pale, flavorless iceberg lettuce when red heads are available? Some people would be delighted with leaves of the wildly spicy Asian red mustard, which is not something one usually sees. With the number of seed catalogs that are sent out every year, there is no reason not to try an unusual cultivar, or even an unfamiliar plant.

Starting seeds is not difficult, but it is relatively easy to make mistakes that lead to big disappointment.

An enormous error would be to use soil from the garden. This is true, not only for seeds, but for potted plants in general. While good garden soil is perfect for growing things outside, it is too dense for containers. It may also contain a type of pathogen that attacks seedlings exclusively. Seed starter mix, or planting mix is a much better choice.

It might be tempting to spread the mix in a tray and plant the seeds as if they were outdoors. While this can work, it is terribly difficult to separate the seedlings when it is time for planting them in the garden. Disturbed or torn roots do not perform their functions adequately, and may be avenues for pathogenic organisms to enter.

Peat coins or individual peat pots filled with mix are a good choice. Each of these holds a single seed and permits it to grow into a good-sized transplant. Plant the seed about as deep as it is wide. If it is too deep, it must spend much energy and resources to reach the light, weakening it.

These must be watered religiously as the peat dries quickly in our environment. It is not necessary to provide supplementary light until the tiny cotyledons have emerged. At that point, the seeds have been transformed into seedlings, and the spring miracle has begun again.

Dr. Angela O’Callaghan is the Social Horticulture Specialist for University of Nevada Cooperative Extension. Contact ocallaghana@unce.unr.edu or 702-257-5581.

The information given herein is supplied with the understanding that no discrimination is intended and no endorsement by Cooperative Extension is implied.

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