“Autumn is the hush before winter” says an insightful French proverb. We never know what kind of fall season we’ll experience until it unfolds. Warm, dry days can keep us outside enjoying the waning days of summer. Breathe it all in while you’re checking the fall garden chores off the list.
Frost
• The nights are cooling down. The question is to protect your plants or let them go.
• Cold temperatures certainly play a role in plant damage or death on both ornamental annuals and vegetables. But humidity (higher keeps plants warmer) and location (lower to the ground keeps plants warmer) are factors, too.
• Light frosts happen with temperatures around 32 degrees, down to about 28 degrees. Hard frosts occur below 28 degrees.
• Warm-season crops (tomatoes, peppers, eggplant, squash, beans, cucumbers, pumpkins, basil) need consistent 55-degree temperatures or higher to grow and ripen properly.
• Semi-hardy cool-season crops (beets, carrots, Swiss chard, lettuce, cauliflower, potatoes, parsley) grow in minimum daytime temperatures of 40 degrees and higher. They cannot withstand hard frost without some kind of covering or protection.
• Hardy cool-season crops (cabbage, broccoli, onions, radishes, spinach, turnips, peas) grow in 40-degree daytime temperatures and can handle some frosty nights without protection.
• Long term, both hardy and semi-hardy cool-season vegetables will need cold frames or covered tunnels to keep them growing through the fall.
• Have some lightweight sheets or floating row covers on hand to cover when lower temperatures are predicted. Plastic transfers cold to the plant, so use only on top of sheets (for extra warmth or rain/snow protection). Covers must extend over the entire plant and be secured to the ground to keep heat trapped inside. Be sure to remove covers the next day when it warms up. More
• If not covering, harvest tomatoes prior to frost — look for mature green tomatoes (dull, light green in color) or ones that are beginning to develop color. Wrap each in newspapers until ripe or place on a rack in a room with 65-70 degree temperatures. Light is not necessary for ripening, although some light will help with the color intensity. Keep them off a sunny window seal to ripen; they’ll get too hot and turn mushy.
• Summer and winter squash are both warm-season crops and will not survive fall frosts. Summer squash includes zucchini, patty-pan or scallop, yellow straight or crookneck and taste best when harvested when they are immature with undeveloped seeds inside. They need to be harvested often and only last about a week in the refrigerator. Winter squash includes butternut, buttercup, hubbard, acorn, kabocha and many pumpkin varieties. The opposite of summer squash, they are harvested when fully mature, and the fruit has developed a hard skin. This helps them store for many weeks in a cool, dry, dark place. A great indicator is to harvest winter squash and pumpkins when a fingernail cannot easily puncture the rind. Leave a two-inch piece of stem attached to the fruit.
Read more from Denver gardener Betty Cahill at gardenpunchlist.blogspot.com
