Seaweed Extract is a plant hormone (aka plant growth regulator) product. The active ingredient is gibberellic acid. If you look at the "Guaranteed Analysis" on the product label, you'll see that very few -- if any -- of the advertised minerals on the label are present. This is because they are not in a form that is available for plant uptake, nor will any soil process break them down into a form usable by plants.
Gibberellic acid and the essential plant oils that contain it do break down relatively quickly in soils because they are utilized by many soil organisms and also react with soil chemistry. Consequently, I see no benefit to supplying it to plants in dormant stage.