In October, time is ripe to plant ornamentals

It's almost time: The air is cooling, the days are growing shorter. Soon, we’ll wake up one morning and it will finally feel like fall — our best planting time.

Why fall? That's when the air is cooler, yet the soil retains its warmth. Warm soil + cool air = ideal planting conditions for nearly every ornamental plant. Here are the chores to take care of this month:

Harvest melons, pumpkins and winter squash once their stems dry out and start to pull away from the base. Leave a few inches of stem attached as a handle. Rinse, dry and store in a cool, dry, dark location.

Let tomatoes, eggplants and squashes continue producing, or remove them to make room for cool season crops.

Don't compost old vegetable plants. Instead, send them off in the greenwaste so they can be hot-composted to kill off pests and diseases.

Plant root vegetable seeds — such as carrots, turnips and radishes — directly into garden beds. Don't buy them as seedlings; they don't transplant well.

Start seeds for kale, cabbage, beans, cauliflower, spinach, lettuce and other leafy greens, either in the garden or in containers to transplant in a month or so.

If winter gardening doesn't excite you, give your garden a break. Rather than planting cool-season crops, plant cover crops to improve the soil. Legumes like hairy vetch add nitrogen; grains add organic matter. Buckwheat chokes out weeds, builds organic matter and suppresses nematodes. Choose the best cover crop seed for your garden. Order and plant the seeds now.

Swap out warm-season herbs, such as basil, for cool-season herbs, like dill and parsley.

Plant lemony perennial herbs for seasoning and cooking: lemon grass, lemon verbena, lemon thyme and lemon balm.

Harvest pineapple guava. These egg-shaped, olive-green fruits grow on evergreen shrubs that reach 12 feet by 12 feet and make wonderful natural hedges. The plant's botanical name is Acca sellowiana, and it is native to South America but grows across Southern California. You know the fruits are ripe when they "self-harvest" by falling off the branches. Simply pick them up, slice lengthwise and scoop out the soft, sweet innards. Yum!

Do you live within a citrus greening quarantine area? The Asian citrus psyllid spreads the bacteria that causes this fatal citrus tree disease, and it has now been found across Southern California, prompting a state-enforced quarantine from Pasadena to Redondo Beach, South Irvine to Redlands, and Camp Pendleton to Bonsall to Carlsbad. It is critically important NOT to move citrus fruits, leaves, wood or any other part of citrus plants anywhere inside or outside the quarantine area. Consume all fruits on-site. Don't move them off-site. Don't share fruits or plant parts. Do not compost fallen leaves, branches or any prunings. Instead, seal them in a plastic bag and place in a closed greenwaste can for collection. Find the quarantine map here.

Plant the last of the year's subtropical fruiting trees and shrubs, like banana, citrus, avocado, cherimoya or tropical guava. Unless you live within a few miles of the coast, plant now or wait until next spring.

Order bare root deciduous fruit trees (nectarine, Pluot, apple etc.) from your local independent nursery. They’ll arrive in the nurseries in January.

Are your citrus trees’ leaves curled and distorted? Do the leaves look marbled? That's classic leaf miner. The larvae's damage looks ugly but doesn't hurt the tree nor diminish production. Don't cut off those leaves; removing infected leaves causes the tree to make new leaves, which will also become infected with leaf miner. Sprays won't help. Just leave it alone.

In the shorter, cooler days of "second spring," watch for established plants like South African daisy (Arctotis) and Grevillea to erupt in bloom.

Once daytime temperatures cool, start planting trees, shrubs, vines and perennials. Focus on the "unthirsty" plants native to California, South Africa, Australia, the Mediterranean and western Chile.

Check your garden for emerging green spears of spring bulbs like Sparaxis, Homeria and species Gladiolus. If you have bulbs you’ve been meaning to plant — do it now. They may not flower next spring, but they’ll bloom the following spring.

Plant annual spring flowers this month and next: California poppies, native farewell-to-spring (Clarkia), native tidytips (Layia platyglossa), flowering sweet peas and many more. Keep the seeds damp until they sprout. Keep young plants damp until rains begin.

Cut back spring and summer blooming sages (Salvia) so they can resprout afresh and flower again.

Divide iris, including native iris and Pacific Coast hybrids. Carefully separate the rhizomes (they look like tiny, jointed potatoes) at the "joints." Use a sharp knife wiped clean with alcohol. Wipe the knife with alcohol again between plants so you don't spread pests or diseases from one plant to the next.

Early in the month, shorten branches of scented geraniums and Martha Washington geraniums by a couple of inches. Next month, cut the long branches to force the plant to grow new shoots at the base.

Feed roses with liquid fertilizer at midmonth. Inspect leaves for mold, rust or black spot. Remove infected leaves and put them in the greenwaste bin rather than into your compost pile.

Rake up leaves as they fall from fruit trees. Unlike with ornamental plant leaves, send these leaves to the greenwaste, where they’ll be composted at a high temperature to kill bacteria, molds, etc.

Before you plant anything new, be sure your garden has a solid infrastructure:

With the sun lower in the sky, plants need less water, so adjust your irrigation clock to water just as long, but less frequently. If you have a smart irrigation controller, check to make sure it is making the necessary adjustments. If your controller isn't "smart," set it to run less often, but don't alter the run time.

"Smart" irrigation controllers adjust your irrigation seasonally, zone by zone, depending on the type of plants each zone waters, your garden's location, type of soil, slope, sun, shade and so on.

When you plant natives and other Mediterranean climate plants, irrigate them with in-line drip irrigation. In-line drip has emitters embedded in the lines and delivers water directly to the soil, where it penetrates down to the roots. Natives do great with this kind of drip irrigation.

Don't use the type of drip that is individual emitters at the base of each plant. These kinds of systems are neither durable nor reliable.

How long should you water? There is no one answer to that question. Always water long enough to saturate the plant's deep roots. Use your fingers or a soil probe to feel how deep the water has gone. Adjust your watering schedule so water reaches the deep roots every time. For drought-tolerant plants, let the soil dry several inches down before deep watering again.

Renew your garden's mulch using organic mulch (made from leaves, bark, wood, etc.) for nonsucculent plants. Mulch succulents and cactuses with rock or decomposed granite. Whichever you use, keep the mulch at 3 to 4 inches thick.

Organic mulches act like a sponge to hold water, keep moisture in the soil and protect soil from erosion. As the mulch breaks down, it feeds the micro flora and fauna that help build healthy soils to support plants. Research shows that mulch can protect plants from soil pathogens, too.

While mulch should cover the soil surfaces in your garden, leave several bare spots for native, ground-dwelling bees — very important garden pollinators that rarely sting.

Sterman is a waterwise garden designer and writer and the host of "A Growing Passion" on KPBS television. More information is at agrowingpassion.com and waterwisegardener.com.