Spring
Install stepping stones in large beds to access plants in the back later in the season without stepping on plants. Spread manure and or a season long fertilizer such as Osmacote around plants before putting mulch down. Trim forsythia after it blooms. A good rule of thumb for fertilizing your yard: Easter, Memorial Day, Fourth of July, Labor Day and Columbus Day.
Summer
Raise mower setting and water in the morning to reduce evaporation and prevent disease. Apply fertilizer and grub control now. Make sure you water well if you fertilize your lawn. Add pots with annuals in your landscape for color. Large pots do not dry out as quickly. Buy perennials all season, plants are featured during their flowering time.
Autumn
Fall is the perfect time to aerate your lawn. Leaves left on the lawn over the winter will damage your turf. Lower your mower settings for the final mowing and apply a winter fertilizer.
Winter
Stay inside and read garden magazines, plan for spring and order seeds. Make sure not to throw piles of snow on bushes to eliminate damage. Trees should be pruned in winter, except for flowering trees which should be pruned after they bloom.