Endangered New Jersey: Starting Seeds to Beat That Last Frost

March is the month when I start looking at my seed packets and the vials of seeds that I saved from last year. But the frost-free date for New Jersey when things should be safe to put in the ground varies.

In my part of northeastern NJ it is April 21 - 30 - but that is also the listed dates for the Atlantic City area. In northwestern NJ, it is May 21 - 31 - and also in Shamong Township in the Pinelands. In other words, it varies. And it is unpredictable.

I keep a garden journal year to year and mark the last frost for my little eco-zone. Over the past 15 years, the last frost in my garden has gone from a late one on May 3 and an early April 10. That's a 3-week spread. My average would be around April 20

That variation is the reason that many Jersey gardeners start seeds indoors. I find saving seeds an optimistic practice. It means I plan to be around the following spring to be in the garden again.

And there are lots of reasons for starting your own seedlings for the garden.

To get ahead of spring and summer planting.
To learn and experiment with growing techniques.
To save money, compared with buying transplants.
To teach children how seeds germinate and plants grow.
To experience the emotional benefits of gardening during winter.
To prevent birds and other critters from eating seeds (like sunflowers) before they can grow.

Plants, such as tomatoes and peppers, need a longer season to mature so sowing seeds outdoors is not an option, and those young plants are not very happy outside even without frost when there are 40 degree nights. There are vegetables and flowers that can be grown successfully directly into the ground. My father always used St. Patrick's Day as the time to plant peas outside and start cleaning out the flower beds.

A pepper seed pack might say to sow indoors 8-10 weeks before the average last frost. Several years I have started seeds too early and the seedlings started to die before I ever got them in the ground.

I start my tomatoes, peppers, and eggplant about 6-8 weeks before that last frost guess date. I also start some annual flowers such as zinnias, marigolds and sunflowers can also be started indoors, but I will sow some outside if it warms up early in mid-April.

Plants that don’t transplant well include root crops like beets, carrots and radishes, beans and peas; and squash family plants like cucumbers, summer squash, winter squash and melons such as watermelon. While perennial flowers often can be started from seed, it typically takes a long time and isn’t worth the investment for most home gardeners.

Seeds can sprout in less than a week if there is sufficient warmth and light. Indoors, the secret is to keep up that light via the sun and perhaps some grow lights too.

I use seed trays that I fill with lightweight soil, peat pots, soil pellets, and some plain old pots with good garden soil, and I track which ones work the best year to year.

I also shuffle my trays in and out of the house trying to grab those warm days and bring them in at night and col days. It's work but I enjoy doing it.

The New Jersey USDA Plant Hardiness Map below shows the four different planting zones, 6a, 6b, 7a and 7b.