Growing annuals like zinnias, marigolds, and tomatoes from seed is easy and economical. The exact time to start seeds varies with the plant and with your location. In general, it’s about six weeks before the date of the average last frost in your area. Seed catalogs and packages usually list the number of weeks needed when starting seeds indoors.

Use a potting mix specially formulated to start seeds; you can find such mixes at almost any garden center or hardware store. The mixes are sterile, provide the drainage that seedlings need, and are sometimes enriched with fertilizer. Fill peat pots or other seed-starting containers with the mix and thoroughly moisten it. Then sow your seeds of choice following the directions on the packet.
Place the containers on a tray in a very sunny window or under a grow light. Never allow them to dry out. As soon as the seedlings develop four leaves, use scissors to thin out your seedlings, leaving just the healthiest looking ones.

After all danger of frost has passed, place the trays of seedlings outdoors in a sheltered place for several days, gradually lengthening the time they are exposed to the sun and wind to prevent scorching the leaves, before transplanting them into the garden.

A little TLC for your perennials
Herbaceous perennials and grasses, a group of diverse and reliable plants that return to the garden year after year, can greatly benefit from a little extra attention in the spring. Here are some tasks that will help your plants get off to a healthy start.

  • Remove winter mulch from around the crowns of perennials.
  • Cut back any parts of the plant that were left up for winter interest, such as flower stalks and seed heads.
  • For evergreen perennials, remove any dead leaves.
  • When new growth is about three to four inches tall, dividing and transplanting may be done. For spring-flowering plants, wait till they are finished blooming.
  • Begin placing stakes to support the growth of tall or fragile perennials.

Pruning early-blooming shrubs
Shrubs that bloom early in the year, such as forsythia, form their flower buds the previous year. In the rush of the spring season, there are always so many chores to do it’s easy to forget that these early flowering shrubs need pruning immediately after bloom. If you wait too long before getting around to it, you’ll cut off next year’s flower buds. And if you don’t prune at all, these strong growers will quickly turn into giant tangles.

As soon as the last flowers fade, use a pruning saw to cut off one-fourth to one-third of the biggest, oldest stems at ground level. Use pruning shears to shorten all of the stems to two or three feet from the ground. If you wish to greatly limit the shrub’s size, you can cut the branches as far back as six inches from the ground. By the end of the growing season, new branches will have formed. These will arch gracefully from the center and will be covered with new flower buds for next year’s spring show

Original Source: http://www.ahs.org/gardening_q_and_a/spring_gardening_tips.htm