Luis and Sandy are right! "Consider" the average frost date, but that's just a prediction. Rely on solid gardening principles by getting to know the climate tolerances of your veggie varieties. (See below for my guide. Get feedback from local gardeners in your neighborhood, a local gardening club, and the local county agricultural extension's advice for your specific area.
Realize a couple of things about the "average last frost date."
1) It's generally from the years of data collected at the official weather station in your area, WHICH MAY OR MAY NOT represent the conditions in your garden.
2) As an average of many years, it's inaccurate for any one year- other than to give you a broad guess.
Proof?
As I look up your city, the 'official' station that has collected data is at the airport.
In the data collected for the last 20 years-
1) the earliest 'Last frost' recorded was in 2020, on March 8th, nearly one month EARLIER than your average last frost date. You lost one full month of gardening if you waited until the average last frost date.
2) the latest 'Last frost' recorded was the very next year in 2021, on April 23, THREE
WEEKS AFTER your average last frost date. You'd be replanting your frost-killed tender transplants if you had set them out without frost protection this year. Seeds sown on the last frost date may have been ok in the ground.
So, using your average last frost date as only a guide, get to know your veggie crops and plant them in the season they like. Here is a guide:
GROUP A - HARDY. PLANT AS SOON AS SOIL DRIES OUT IN THE SPRING. These tolerate frost.
ASPARAGUS
RHUBARB - Perennial
BROCCOLI -
CABBAGE -
KOHLRABI -
ONIONS - for sets or transplants,
PEAS - Likes cool weather- later plantings may not produce if weather gets hot
RADISH - Likes cool weather
SPINACH - likes cool weather,
TURNIP - likes cool weather
GROUP B - SEMI-HARDY. PLANT A WEEK OR TWO AFTER "A" GROUP. These can tolerate some frost.
BEET -
CARROT -
CAULIFLOWER
LETTUCE - likes cool weather, late plantings may become bitter and "bolt," or set seed. PARSLEY -
PARSNIP -
POTATO -
SWISS CHARD – likes cool weather,
GROUP C - TENDER. PLANT ON AVERAGE DATE OF LAST SPRING FROST. These seedlings or transplants cannot tolerate frost.
Frost & Seeds Note: Seeds of tender plants can generally be sown 5 -7 days earlier – as the soil will offer a few degrees of frost protection for seeds not yet above the ground. However, if seeds are already above ground when a frost occurs, or the frost is cold enough to penetrate in the ground, you may lose the crop and need to reseed. Also, cold, wet soil can inhibit sprouting and encourage rotting of seeds. Consider the cost of your seed, your planting effort, and the weather conditions before "pushing" the season.
SNAP (GREEN) BEAN –
CELERY
SWEET CORN -
CUCUMBER - sow seeds indoors 2 weeks earlier in peat pots to get an earlier start.
SUMMER SQUASH (& Zucchini) sow seeds indoors 2 weeks earlier in peat pots for early start
VERY TENDER group. PLANT WHEN THE SOIL IS WARM, ABOUT TWO WEEKS AFTER "C" or, two weeks AFTER your average last frost date. These plants listed below love warm conditions and will not thrive until it warms up, and may not sprout or mature any earlier, even if planted earlier. Buy plants, or start Tomato and Pepper seed indoors 6 – 8 weeks early, and 2 -3 weeks early in peat pots for cantaloupe, squash and watermelon. If grown indoors, harden transplants off by setting outside in sheltered location in daytime, bringing pot in at night, until weather warms.
CANTALOUPE –
EGGPLANT -
PEPPER - Loves hot weather! Plant them last. No kidding here- plant these last of all.
WINTER SQUASH (& pumpkin) –
TOMATO - Use hot caps, milk jugs, frost covers, wall-of-waters, etc. if planted earlier
WATERMELON –
Use frost protection anytime the weather predicts a drop below 38-40 if you have tender veggies in the garden.
Good luck with the garden planning! washed gallon milk or water jugs, hot caps, wall-of-waters, or frost blankets (floating row covers) can protect from several degrees of frost.
