X

St. Lawrence County gardeners should take note of last frost date

Posted 3/28/16

By PAUL HETZLER Gardeners are a patient lot for the most part, taking note of each winter milestone that indicates spring will probably come again someday. There’s the arrival of the first nursery …

This item is available in full to subscribers.

Please log in to continue

Log in

St. Lawrence County gardeners should take note of last frost date

Posted

By PAUL HETZLER

Gardeners are a patient lot for the most part, taking note of each winter milestone that indicates spring will probably come again someday. There’s the arrival of the first nursery catalogs, and then a shipment of seeds shows up in your mailbox, and finally one morning the first robin song is in the air. But the time they have looked forward to more than any other, that blessed moment that signifies positive change and new growth—I’m speaking here of winning the lottery—has not yet arrived for most gardeners. Unfortunately, the time to begin planting seeds indoors is not quite here yet either.

Given that the planet has had a mild winter—the warmest on record, in fact—it’s easy to get antsy about getting some seeds going. While certain flowers like begonias and pansies need a twelve-week head start, many vegetables should be started indoors much later. Start your tomatoes, peppers and eggplants no more six weeks before last frost, while cukes, melons and squash need only three weeks in the house. Crops in the cabbage family can be planted eight weeks out because they are frost-tolerant and can be moved to the garden earlier.

A word about last frost—OK, a couple words. Depending on your elevation (where you live, not your height), there can be a 30-day difference in last frost dates across northern NY. You can look up first and last frost dates for your location at http://www.gardening.cornell.edu/weather/sprfrost.html

The other word is that the National Oceanic and Atmospheric Administration (NOAA) has recent data which indicate the El Niño effect, the phenomenon that gave us a warm fall and winter, is “collapsing” (their term), giving way to something called the La Niña effect. I don’t pretend to understand these contrarian twins, but according to NOAA, apparently La Niña portends a checkered spring with several late frosts likely for us. For the Midwest it means a hot dry summer—go figure.

No matter when you start indoor seeds, the same guidelines apply. You can use any container with good drainage and at least three inches deep. If they were used last year, sanitize them in a ten percent bleach solution. Soil should be—well, not soil. A so-called sterile potting mix containing peat moss, vermiculite and/ or perlite is free of disease spores contained in actual soil, and provides the drainage needed to avoid root rots.

Read those seed packets carefully—they are full of good information. Seeds are generally planted two to three times as deep as they are wide, and kept moist but not waterlogged. It is better not to cover the flats or containers with plastic. Most seeds germinate best when the soil is kept at about 75 degrees (cabbage family crops will germinate at cooler temps). After they come up, plants do well between 65 and 70 degrees.

Unless you have a greenhouse, artificial light is critical. Even a big south-facing window will not provide enough light for seedlings to develop properly. Plus a windowsill is far too cool to germinate seeds. To save money you can use a regular 2-bulb (tube) fluorescent light fixture with one 40W “cool” and one 40W “warm” bulb. Lights should be kept on between 12 and 16 hours a day. Adjust the fixture so the lights are about four inches away from the seedlings.

After the first set of true leaves develop, fertilize with a dilute (half- to one-third strength) fertilizer solution every two to three weeks. depending on the containers, you may need to transplant, but wait until after the second set of true leaves appear. Seedlings will need a hardening-off period before being moved to the garden. Take them on “outings” a few hours each day, in a spot sheltered from wind and full sun.

Paul Hetzler is a forester and a horticulture and natural resources educator with Cornell Cooperative Extension of St. Lawrence County.