Frost seeding helps improve pastures

By Gary Sliworsky
OMAFRA Rep.

There is a large risk with frost seeding but you can afford to attempt it 3-4 times for the same price as conventional seeding. Your patience and need of forage will determine if it is a good option. In general we assume that legumes will be effective 50-60% of the time and grasses about 20-30%. Some springs you will see no response and others will be excellent.
Legumes such as trefoil, clovers and alfalfa work best when frost seeding as their seeds are round and dense so they roll into the ground as it opens and closes during the freeze and thaw cycles. They germinate at lower temperatures than grasses and thus make use of all the available moisture in the spring to germinate and establish. Grasses can be frost seeded but tend to sit on top of the ground and wait until the temperatures warm. This often leaves them sitting on dry ground or worse, germinating but lacking a constant water supply.
Alfalfa plants produce a chemical substance that will not allow new alfalfa seeds to germinate within a metre of an old plant. This means you can’t thicken alfalfa stands with alfalfa. The only exception is in the first production year as there are no ‘old’ plants yet. Red clover will give good growth during the first growing season but only for one season. Trefoil will not be evident during that season but will establish for future seasons.
Pastures benefit greatly from frost seeding. The introduced legumes provide a high quality feed and, most importantly, fix nitrogen which they ‘share’ as their roots rot over time. This improves existing grasses as well. You will have to decide how tolerant you are of a bloat risk as only trefoil can provide a bloat free pasture.
When timing frost seeding consider that you want the ground to freeze and thaw a couple of times after broadcasting the seed. A prolonged warm period may encourage seed to germinate only to be killed with cold temperatures if they return.

Dates to remember
Mar. 27 - Rainy River Cattlemen’s Spring Sale, Stratton Sales Yard