THE COASTAL GARDENER:

Mid-September marks the beginning of what should be the most active time in our Orange County gardens. Mild temperatures over the next three months or so make gardening tasks pleasant. Additionally, warm soils combined with cooler air temperatures make this an ideal time to focus on cleaning up the old garden while getting a new one under way.

Here are some seasonal chores to consider, specific to your local Orange County garden.

Sow seeds of cool season vegetables now: Beets, bok choy, broccoli, Brussels sprouts, cabbage, carrots, cauliflower, celery, chard, collards, endive, kale, kohlrabi, leeks, lettuce, onions, parsley, peas, radishes, spinach and turnips are just a few. Wait another month if starting from transplants.

If you are growing melons, squashes or determinate tomatoes, pinch off the new growing tips and any new flowers. This will direct the plants’ energy to the fruits that have already set. New flowers on these plants at this time of the year wouldn’t ripen properly anyway, so don’t let the plant waste its energy.

Plant sweet pea seeds. Create a mixture of short-day varieties like “Winter Elegance” and main season selections. A blend like this will provide beautiful, fragrant flowers for the garden or the vase as early as Christmas and all the way through spring.

Plant perennials, ground covers, shrubs and vines while the soil and air temperatures are still warm. Fall planting will give them several months of root growth and a big advantage over those planted in the spring.

Plant new bearded iris rhizomes right away. Bearded iris prefer to be planted almost to the top of the soil and in a full sun location. Existing bearded iris should have their leaf fans trimmed to about eight inches. Divide the clumps if you haven’t for the past three years or if flower production was reduced this year. Discard the old, leafless center sections, snap off the new rhizomes, with leaves attached, and re-plant them just below the soil surface.

Plant landscape trees while the soil is still warm to encourage the roots to get established before next summer arrives. Decide what you want from the tree, where it will be planted and for what purpose. If you want to cool the house or garden during the summer, a deciduous tree planted on the south side would be perfect. If you prefer to frame a view, a grouping of Silver Sheen Pittosporums may be perfect.

Feed lemons, oranges and other citrus for the last time this year and reduce irrigation as the weather cools. Don’t worry too much about pests like leaf miners, scale or whiteflies this late in the year. In another month, the cool night temperatures will take care of them for you.

Give azaleas and camellias a feeding of cottonseed meal or an organic acidic fertilizer to encourage the development of next spring’s flower buds. Increase the individual size of next spring’s camellia flowers by twisting off a portion of the small new flower buds. For the best show, leave one bud per cluster, spaced evenly along each stem.

In anticipation of a big fall rose bloom, this is the last month to feed roses. Continue to water them regularly, as the weather dictates.

Keep irrigating tuberous favorites like begonias and dahlias, but in a month, start withholding water and force them into dormancy. When the tops dry completely, dig up the fleshy roots and store them until it’s time to plant them again next spring.

Shop now for winter- and spring-blooming bulbs such as amaryllis, anemones, brodiaeas, crocus, daffodils, freesias, muscari, Dutch iris, ixias, leucojums, lycoris, narcissus, scilla, sparaxis, triteleia, tulips and watsonias.

Shopping early allows you to choose the biggest, plumpest bulbs in the bin. A few of these can be planted right away, but most should be stored for another month or two until the soil cools.

Don’t forget to buy some Paperwhite narcissus to have bloom for Thanksgiving and Christmas.

Trim hedges like boxwood and privet for the last time this year. Trimming these later in the year will leave scars all winter.

Perhaps most important to a healthy garden is continuing to manage and improve your soil. Add a healthy layer of organic mulch over the surface of any exposed soil and remember not to discourage valuable soil life by using synthetic fertilizers, harsh chemicals or excessive cultivating.

Continue building up your compost pile; or, if you don’t have one, start one now. Old flowers and plant clippings add a lot of bulk, along with grass clippings.

Soon, fallen leaves from deciduous trees can be included. Chop up items before adding them so they decompose faster.

Question: What is the best red seedless grape for my climate? I want it to be really flavorful with a crisp texture.

Jack

Newport Beach

Answer: The two grapes to consider are ‘flame’ and ‘ruby.’ My experience is that in the cooler coastal zones ‘ruby’ is a slightly better choice. It is seedless, dark red, sweet and crisp. It is also excellent for raisins.

ASK RON your toughest gardening questions, and the expert nursery staff at Roger’s Gardens will come up with an answer. Please include your name, phone number and city, and limit queries to 30 words or fewer. E-mail stumpthegardener@rogersgardens.com, or write to Plant Talk at Roger’s Gardens, 2301 San Joaquin Hills Road, Corona del Mar, CA 92625.

RON VANDERHOFF is the Nursery Manager at Roger’s Gardens, Corona del Mar