Now is a good time to add beneficial nematodes to your lawn to kill those grubs.  Grubs are Japanese beetle larva that eat the roots of your lawn until they mature.  this can be yet another reason why your lawn might turn brown in the summer.  your can also get insecticides at your local nursery, but be careful to read the directions CAREFULLY so not to harm pets or children that might cross or play on the lawn (nematodes on the other hand are not harmful to pets and children).

Remove all the spent flowers before they set seed except on Columbine.   This will make the plants put more energy into producing more flowers instead of developing seeds.  Columbine only flowers once however and those seeds can be used to spread Columbine to other parts of the garden.

Remember to mark any of those spring bulbs that you might want to divide or more in the fall.  Dividing bulbs is a great way to increase the flowers in your garden as well as keeping them healthy.  A good rule of thumb is to divide plants at the end of every third year. You can usually divide a single plant into three thus tripling your garden in three years.   A good thing to keep in mind when  designing your flower beds.

To help keep down those weeds try using mulch such as small wood chips, shredded leaves or even grass clippings.