Now seems like a good time to talk about autumn in the Southern California garden, and fall planting. As the weather cools, all sorts of things can be planted. Some must be--such as bulbs and spring flowers--and some can be: trees, shrubs and ground covers, which will get off to a better start planted in the fall than if you were to wait for the traditional spring start date.
Sunset magazine's former garden editor, Joe Williamson, swears that this fall planting season begins precisely on Tuesday. He has told me that you can see cool-weather-loving bluegrass lawns perk up overnight, a sure sign that the stressful days of summer are over.
I haven't noticed this overnight change myself, but I always put a big, red circle around Sept. 15 because Joe is one of the more observant gardeners in the state. I have noticed that somewhere in mid-September we historically get the hottest weather of the year--due about now--but that after this miserable week, it begins to feel like autumn. More to the point, I have noticed that if I don't get started in mid-September, I never get everything in the ground in time because there is so much to do, and not that many weekends to do it in.
Ground Too Cool
I figure 10, counting this one, because after Nov. 15 the ground is too cool for plants to accomplish much growth; they just sit there passing the time until mid-February when they sense spring coming and begin growing again.
There are two groups of plants that can be put in during the fall. The first is those plants that are both permanent and evergreen, which includes most of the trees, shrubs, and ground covers we grow in Southern California. In truth, these can be planted at almost any time, or season, but fall is a special opportunity.
Because the soil stays warm even as the days cool, plants can make considerable growth, especially below ground at the roots. Apparently, fall is the favored time for root growth, even though you may not see much going on topside.
Winter's rains help with the watering of new plants, and when spring arrives those planted in the fall are quite at home in the garden and more than ready to join in the growth spurt. More important, they have the root system to support this built-in burst of enthusiasm.
The planting of most bulbs, spring flowers and those vegetables grouped in a category called "cool-season" is another story. These \o7 must\f7 be planted in the fall because they only grow during cool weather and flower or produce in spring. They, too, should be in the ground by Nov. 15. (There is one exception: Tulips should be purchased now, but because they require more cold than California can provide, they first must go in the refrigerator for about two months, and then be planted after Nov. 15.)
Many of the flowers and vegetables can certainly be planted later, but the sooner they are planted the sooner they will produce or flower. Wait until winter or spring, and their season will be short and you will find them still in bloom when it is time to plant summer's flowers and vegetables.
Get Started Soon
So the important thing--the reason for that big, red circle--is to get started. Since this summer has been mild and the possibility of a late hot spell looks less and less likely, I'd suggest jumping the gun and starting this weekend.
Since you have a few extra days, take time to prepare the soil by digging in a few bags of soil amendment before replanting. First to be planted should be the cole crops--broccoli, Brussels sprouts, cabbage and cauliflower--and three flowers that do best with an extra early start: calendulas, Iceland poppies and sweet peas. Daffodils and most of the South African bulbs, including babiana and freesias, also like an early start.