As I write this, the dandelions are beautifully puffing white and going to seed.
This is the perfect time to spread corn gluten meal to prevent those seeds from
germinating and becoming new dandelions in your yard.

What is Corn Gluten?

Processed from corn, corn gluten meal comes in the form of small granules that
you can spread over your yard with a hand-held spreader or a fertilizer spreader.
It prevents weed seeds from sprouting and is most useful when
applied in the spring before weed seeds germinate. You can also apply it in the
fall for some effect in the spring. You can usually find it in the spring
and fall at garden centres and organic grocery stores. If you have extra (often a
bag will be enough for two applications), store it in a sealed container so that
mice canʼt get at it.

According to Jim Ross of the Prairie Turfgrass Research Centre at Olds College
in Olds, Alberta, corn gluten works well to prevent new weeds if the weeds that
are already there are eradicated. (This means digging them out!) Ross says that
96% of new dandelions come from the spring seeds that disperse. Those seeds
sprout within 2 to 3 weeks, making it most effective when applied at the
time that dandelions go white and fluffy.

Corn gluten also acts as a mild fertilizer
so it will stimulate the growth of your grass, which may require more mowing.
Caution: If you overseed new grass seed on your lawn, or are planting other
seeds, do not put corn gluten in these seeded areas as it will prevent your seeds
from sprouting. Please wait until about a month after your seeds have sprouted to apply.
And you may be tempted to spread corn gluten in the park – donʼt do it! Some
people are really allergic to corn and itʼs best not to expose them to it.