When Can I Plant this Spring?

• Mar 16, 2026
• by Rebecca Auchter

If you're excited to get outside and get your hands dirty, there's plenty of plants that are ready to go in the ground right now!  Any perennial plants (this includes trees, shrubs or herbaceous perennials) that are labeled for our hardiness zone can be planted any time the ground isn't frozen.  Here in the Pittsburgh, PA, region we are in USDA hardiness zone 6b and city gardners can plant zone 7a selections with very good success given an extra bit of winter protection.  USDA hardiness zones are determined by the "average annual extreme minimum temperature" for a given location.  For hardiness zone 6b, this is -5 degrees F. 

This is where it gets a little slippery with the terms annual and perennial plants.  We mistakenly call many plants "annuals" because they are not hardy to zone 6b and we can only grow them here in the summer.  However, they are just fine to live outside all year a little further south.  A great example is Lantana.  We call this an "annual" and plant it alongside our petunias that flower for a few months and then go in the compost heap in September or October.  However, Lantana is absolutely a perennial, flowering plant or shrub when it lives in USDA hardiness zone 8 or warmer climates.  Our vegetable-garden-favorite tomatoes are even perennial plants that can live for many years in their native tropical environment!  And then there are plants that are truly annuals.  They have a lifecycle that sprouts from a seed, flowers, then produces and drops seed before it naturally dies all in the same season.  A good example of this is crabgrass.  It is a prolific seed producer and will come back year after year in the same location but each plant's natural lifespan is a single growing season.  The point is this:  if the plant is hardy to zone 6b you can plant it right now!

For those plants that we grow as annuals, whether or not they may be perennials somewhere warmer, you'll need to wait until the risk of a heavy frost is gone for the season.  The rule of thumb in our area is Mother's Day or sometime in early May.  Many gardeners like to get a head start and get their plants in the ground in mid-April to capitalize on a few extra growing days.  Beware, however, that you'll need to cover the plants when there is a threat of frost.  If you're up for a few weeks of hassle, you can certainly get those tender "annuals" in during April.  Stop by the Lawrenceville Garden Center to check out our wide selection of annual and perennial plants!