Amy Williams

Amy Williams

Dear Garden Guru,

My husband and I planted a fall garden, but we aren’t sure how to tell when to harvest. We planted typically fall plants like broccoli, cabbage and greens as well as carrots and radishes. Can you give us some advice?


Unsure in Oak Forest

Dear Unsure,

Fall provides us with a season to grow a wide range of plants with differing harvest times, leaving many gardeners with the same questions you are facing.

Let’s begin with the most commonly grown flowering brassicas, broccoli and cauliflower. You will want to wait to harvest until a distinct “head” forms at the center of the plant. The broccoli head is composed of a cluster of flowers and should be harvested when the average measure from one side to the other (the diameter) reaches 4 to 8 inches. If you notice yellow flowers opening, be sure to harvest immediately. Note that the stalk and small tender leaves of the plant are also edible, and once the large head is harvested, you can expect to enjoy many smaller shoots off the broccoli stalk.

Cauliflower will form a firm, white, compact head and should be harvested at 6 to 8 inches In diameter. Cut on the main stem while leaving a few outer leaves on the base of the head, which serve to protect it. Though it is less prolific than broccoli, you may expect a secondary harvest of smaller shoots off the stalk. The leaves are also edible, similar to kale in flavor, and are a great addition to stir fry.

Cabbage will form a head in its center and should be harvested when the head is firm and about 6 to 8 inches in diameter. To harvest, make a clean cut just below the base of the head. It’s not widely known, but if you make your cut closer to the base of the cabbage, leaving a few of the outer leaves in tact, you will get a secondary harvest. This could yield several smaller heads of cabbage, similar to the size of Brussels sprouts!

Harvesting greens gives you a little more leeway. Greens can be harvested and eaten just about any time in their development. This includes leafy greens like collards, chard, kale and mustard greens as well as lettuces. If you started them from seeds, you should expect a harvest roughly two months after planting. I recommend harvesting early in the day, or in the evening when it’s not too hot, and also harvesting when you have enough that you can use them in an intended dish. Greens are the plants that keep on giving, so expect to harvest frequently and for an extended period of time. Kale and chard are a biennial, with a two-year life cycle. Though not widely considered a biennial, collards may behave the same in our mild winter climate.

Root vegetables can be tricky as it’s difficult to tell what exactly is happening below the surface. Here are a few clues to help you know when to harvest:

If you planted carrots, radishes and beets from seed, begin checking for readiness about two months after planting by checking the stems for dark green leaves, and a diameter similar to the size of a quarter. Because these vegetables grow partly above the soil, you’ll notice they tend to “pop up” when ready. This will give you a clear indication of the size and if it’s ready to be harvested. The leaves are also edible, so if you find yourself impatient, snip a few of the top leaves off and add them into a salad!

See you in the Garden!

Do you have questions for the Garden Guru? Email Amy at

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