The best time to sow chard falls between 2 to 4 weeks before your last spring frost for most gardeners across the United States. Knowing when to plant swiss chard in your zone helps you get the longest harvest season from each planting you put in the ground this year.
Your swiss chard planting time depends on soil temps more than air temps based on my years of growing this leafy green crop. Seeds sit in cold wet soil and rot if you plant them too early in spring before the ground warms up. I wait until my soil reaches at least 40 degrees F (4 degrees C) before I put any chard seeds in the ground now.
Swiss chard germinates best when your soil temp sits between 55 and 75 degrees F (13 to 24 degrees C) at planting depth. Seeds sprout in about 5 to 7 days at these warm temps which is fast for a leafy green. Cold soil slows things down and your seeds may take two weeks or more to come up if the ground is still cool from winter.
Wisconsin Extension suggests you plant chard about one month before your last frost date and continue through midsummer. This gives you a wide window to get seeds in the ground over several months. You can make several small plantings over this time frame to keep fresh young leaves coming all season long from your garden.
I tried spring and fall plantings side by side in my garden three years back to see which timing worked best. The spring plants gave me leaves all summer but got bitter during the hot July and August weeks when temps stayed above 85 degrees. My fall planting came up in late August and gave me the sweetest leaves I have ever grown right up until hard frost hit in November.
For a fall harvest, count back 10 weeks from your first expected frost date and sow your seeds then. This gives your plants enough time to grow big before cold weather slows them down for the season. Fall chard tastes sweeter than spring chard because cool nights help the plants make more sugars in their leaves for a better flavor.
Your hardiness zone changes when you can plant your chard seeds each year. Gardeners in zones 3 to 5 should wait until late April or May for spring planting. Those in zones 7 to 9 can plant as early as February or March when the soil warms up enough to work safely.
Check your soil temp with a cheap probe thermometer before you plant each year to take the guessing out of timing. I bought one for less than ten dollars at my local garden store and it has saved me from many failed plantings. Stick it three inches deep in your garden bed first thing in the morning to get an accurate reading.
You can extend your harvest by making new plantings every 3 to 4 weeks from spring through late summer. This gives you young tender plants coming ready to pick as older plants slow down or bolt in heat. Stagger your plantings and you will have fresh chard leaves from spring all the way through fall frost.
Look up your local frost dates online if you do not know them off the top of your head. Your county extension office can help you find this info for free. Once you know your frost dates, count backward and forward to find your ideal planting windows for both spring and fall crops of chard in your garden this year.
Read the full article: How to Grow Swiss Chard Successfully
