Ask a Master Gardener: Difference between coated and plain seed

  • Published: Wednesday, April 15, 2020

Readers can pose questions or get more information by calling 417-874-2963 and talking to one of the trained volunteers staffing the Master Gardener Hotline at the University of Missouri Extension Center in Greene County located inside the Botanical Center, 2400 S. Scenic Ave., Springfield, MO 65807.

Q. What is the difference if a seed is called “pelleted” or “coated” or just a plain seed? L.M., Ozark

Answer by Master Gardener Mark Bernskoetter.

A pelleted seed is a normal seed which has been covered with some sort of produce that will provide some benefit.

Originally, pelleted seeds were developed for farms and other big, commercial growers who use machines to sow seeds. The pelletizing was to make the shape of the seed easier for the machines to handle — encasing seeds gave them more uniform shape and size so they would not jam mechanical seeders or flow through too quickly, providing more even distribution of seed over each row and acre.

Pelleted seeds are easier for the home gardener as well. Most seeds are pretty tiny to deal with, tedious to separate and spread evenly in your growing area. The pelleted seed is easier to grasp and they tend to not cling to each other at all. With their typical round shape, they easily roll off your fingers when you are sowing.

When using a pelleted seed, check the seed package label for how many days it should take to germinate. Be sure to keep the soil evenly moist, but not soggy for that many days after sowing. This helps the pellet material to break down so the seed can sprout more easily.

Pelleted seed is often only good for the year it is intended to be grown. Check the package label for what year it is supposed to be sown. The pelletizing process shortens the viability of the seed. If you try to save some pelleted seed for next year, it will often have a poor germination rate.

Some gardeners confuse pelletizing with coating of a seed. Most seed you will purchase in stores and online is coated with something intended to help it grow more reliably.

The most common coatings of a seed is a fungicide, which promotes better germination and inhibits the growth of fungus as the seed is germinating, reducing the incidence of rot and disease, like the process known as damping off (when a new seedling suddenly rots off at ground level).

Sometimes seeds are coated with a coloring, usually to make them less attractive to birds that may pick them out of the soil before the seed ever has a chance to sprout.

Another coating common to some seeds you may purchase (like corn) is insecticide to help the seed resist some of its common pests.

Seed science has developed to the point where some have tested temperature-sensitive polymers that break down at certain temperatures. This would keep the seed fully coated until the soil temperature reached a certain level, then the polymer breaks down and moisture can get to the seed so that it geminates.

Writer: Kelly McGowan

Media Contact

Kelly McGowan
417/881-8909

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