UNITED STATES—The difficult part will be removing the aging warm season vegetable plants while they are still trying to produce. That is one of the disadvantages of gardening in such an excellently mild climate. It would be easier if frost or cooling weather caused them to start deteriorating by now. Perhaps some are already getting tired. Regardless, their space is needed for new cool season vegetables.

Some of us like to amend the soil in between some of the lingering warm season vegetable plants, and add seedlings of cool season vegetable plants. Then, there is less of a rush to remove the warm season vegetables as they succumb to autumn weather. Some of us just wait for the warm season vegetables to finish, which is a delaying compromise for the new cool season vegetables.

Whatever the preferred technique is, it is now getting to be time to plug in seedlings of broccoli, cauliflower and cabbage. Kale seedlings may be added as much as a month later. Seedlings can be purchased from nurseries. Those of us who want particular varieties that are unavailable in nurseries might have sown preferred seed in flats a month or so ago, to be ready for planting now.

Beets, carrots and turnips, like all root vegetables, should be grown from seed sown directly into the garden. Roots get disfigured if grown in flats or cell packs, and then transplanted. Besides, so many individual plants are needed, that such quantities of cell packs would be expensive. Seed for turnip greens, although not grown for their roots, likewise gets sown out directly, and about now.

Seed for leafy lettuces, spinach and peas should have been sown already, but it is not too late. Kale can alternatively be grown from seed sown directly now, rather than from seedlings plugged in later. If preferred, larger heading lettuces can be grown from seedlings plugged within the next month or so. Cucumbers can be risky. If seed has not yet been sown, seedlings can still be plugged.

Whether grown from seedlings or seed, this is only the first phase of cool season vegetables. For some, later phases will prolong harvest.

Highlight: carrot

Bugs Bunny was an expert. He was always chewing on a carrot, Daucus carota, and rudely talking with his mouth full. Because carrots can be stored in refrigeration for a few months, Bugs Bunny could get one whenever he wanted to. However, in home gardens, they are cool season vegetables that are grown through spring and autumn, but not through summer or the middle part of winter.

Carrots are biennial. They complete their life cycle in two seasons. They are vegetative during their first season, as they produce their edible and elongated conical taproot. If not harvested, they bloom and go to seed in their second season. By then, their fat roots are tough and useless. Carrots are ready for harvest in three to four months after their seed are sown, depending on variety.

Carrots are famously bright orange. Yellow, white, red, purple and black varieties have been gaining popularity in the past many years. The longest carrots might be a foot and a half long, but most are less than half as long. Many are only about four inches long, or less. They may be as narrow as half an inch, or wider than two inches! Some carrots are more uniformly cylindrical than conical.

Horticulturist Tony Tomeo can be contacted at tonytomeo.com.