Late summer is prime time for vegetable harvest

A woman harvests zucchini in her vegetable garden.
Harvest vegetables as they ripen in the garden, Nan Sterman says. The more you pick, the more your plants will produce.
(Getty Images)

The high temperatures of August and early September probably aren’t the end of it. Expect heat until at least mid-October. These are the most important months to pay attention to whether, when and how much to water the different kinds of plants in your garden.

Personal care

• Garden in the early hours and late afternoon. Head to the shade before lunchtime. Once the sun is well past its highest point, it’s safe to head outdoors again.

• Wear a hat, long sleeves and sunscreen to protect your skin (don’t forget the tops of your feet and toes).

• Remember to use bug repellent, especially in the afternoon and evening.

• Stay hydrated: water, iced tea, juices, but no alcohol until your outdoor workday is done.


• This is prime harvest time. Tomatoes, eggplant, basil, peppers, squashes, cucumbers and much more. Enjoy!

• What’s a vegetable and what’s a fruit? Any part of the plant that has seeds is technically a fruit: tomato, pepper, eggplant, squash and so on. Any part that doesn’t have seeds is a vegetable: lettuce (leaves), carrots (roots), artichoke (buds), celery (stems) and so on.

• Harvest produce as it ripens. The more you pick, the longer the plants produce. The sooner you pick, the fewer critters get to them first.

• Check cucumbers and summer squash every day to avoid winding up with fruits the size of a baseball bat.

• Store tomatoes in a single layer on the countertop instead of in the refrigerator. Set them stem-end down to keep them fresh.

• Extra tomatoes? Wash, dry, then freeze them whole in zip-top bags. Or slather in olive oil, garlic and oregano, then dehydrate them to raisin-dry.

• When to harvest pumpkins, melons and winter squash? Check where the stems connect to the fruits. Pick once the stem turns the color of straw and starts to pull away from the fruit.

• Remove yellow and browning leaves from vegetable plants. Don’t panic when older leaves die. Leaves don’t last forever, especially not with annual plants.

• To prune or not to prune? Not. More leaves = more energy = more flowers = more fruits. Leaves are the plants’ energy centers. Their chlorophyll (the green pigment) is where photosynthesis — energy production — happens. So removing leaves reduces the plant’s ability to make fruits.

• However, too-dense branches create humid conditions that encourage powdery mildew. If you have issues with powdery mildew, selectively remove branches to increase air circulation in the center of the plants.

• Soft brown spots on the bottom ends of tomatoes, peppers or squash are blossom end rot. You may read that blossom end rot is a calcium problem, but our soils have more than enough calcium (that’s what makes our water “hard”). The problem arises when soil moisture is inconsistent. So solve the problem by evening out irrigation to keep the soil consistently damp all the time.

• Prepare for fall. Order cool-season vegetable seeds and fall cover-crop seeds now. Sow seeds starting in September.

Fruit trees

• Is it time to add more irrigation to your fruit trees? Spread the irrigation wide to water the critical surface roots. Use inline drip laid out in concentric circles that start about 10 inches out from the trunk of mature trees and six inches out from the trunk of young trees. Space the rest of the circles so there are 10 to 12 inches between them. The widest circle should be about one foot beyond the widest part of the canopy.

• Run the water for an hour or more each time so water penetrates deep to the roots. Wait until the soil feels almost dry before watering again.

• Mulch is critical for holding that moisture in the soil. Spread a 3-inch-thick layer of wood-based mulch across the entire planting bed, covering the drip irrigation.

• Feed all fruit trees with organic fertilizer formulated for each type of tree (stone fruits, citrus and avocado, etc.) Pull the mulch back and sprinkle granular fertilizer onto the soil around the drip lines and hand-water it in. Or wet the soil with liquid fertilizer. Then replace the mulch.

Avocado alert

• Let avocado leaves accumulate under the tree; leaves keep the soil moist and cool. As they break down, the nutrients recycle back into the tree.

• Don’t dig, plant or rake under avocado trees. Their shallow surface roots are easily damaged.

• Leave the lower branches to form “low skirts.” Their leaves protect the sensitive bark from sunburn.

• Paint the bark of young trees that haven’t yet developed dense branches. Use orchard paint or interior latex paint mixed 50/50 with water.

Deciduous fruits

• Prune peaches, plums, apples, etc., now to keep branches short and next year’s fruit within easy reach. After the leaves drop in winter, you’ll prune again to shape the tree.

• Collect and compost fallen fruits, damaged fruits, overripe and rotting fruits.

• Pit and freeze extra stone fruits, raw or cooked. Later, thaw them to use in pies, crumbles, compotes and more.

• Ferment stone fruits to make fruit wine, vinegar, kombucha and more.

• Sample grapes to determine when bunches are ready to harvest. No reason to use fancy tools — just do a taste test.


• Plan, don’t plant. The cool months of fall and winter are planting months. Those planted now will be very hard to keep alive.

• Watering established native shrubs and trees — as well as those from South Africa, Chile and Australia — is tricky. These plants all come from areas that have no summer rain, so water them just occasionally, if at all (once a month or less, depending on your location). If their leaves start to brown, do not water. Chances are, you already overwatered. Warm, wet soil encourages types of fungi that attack the plants’ roots. Wait until winter to see whether the plants survived.

• When you do water, use in-line drip irrigation and run it at night when the air and soil are coolest.

• Deep-soak newly planted natives no more than once every four weeks and spritz lightly between deep waterings. Let the soil drain in between. Waterlogged soil can kill these plants.

• Remove spent blooms on roses to encourage fall flowers. Fertilize with organic rose food (follow label directions). Water deeply periodically.

• Plumeria are at peak bloom, so shop for your favorites now.

• Water hanging baskets every few days, since they dry out quickly in our arid climate.


• Keep an eye out for scale — insects that look like oval brown spots on plant stems. Check the plant stems for juvenile scale, which are pale yellow, almost translucent and smaller than the adults. Scrape them off with your fingernails or dab with a cotton swab dipped in rubbing alcohol.

• Give houseplants a late-summer vacation by putting them outside under the shady branches of a tree or under protective eaves. Allow your garden predators to keep pests under control. The breeze will blow pests away, too.

• Not all plants sold as houseplants are actually suited to living indoors. Trees, succulents, herbs and more look sweet in your kitchen or living room, but they grow much better planted in the soil or in very large containers outside.


• Are you watering in accord with current restrictions? Check your water district’s website for how often and how long you can run overhead sprinklers. Most restrictions don’t apply to drip irrigation or hand watering.

• Droopy leaves in the morning are a signal that a plant needs water — droopy leaves in the afternoon are not.

• Turn on each zone in your irrigation system and walk the lines while it is running to check for any problems.

Check drip irrigation for breaks (sprays or geysers), leaks and clogged emitters. Flag problems so you can find them once the water is off.

Flush drip lines — turn on each zone, then open the flush valve for each bed, or open the end of the lowest elevation line in a bed. Let the water flush through for a few minutes before closing valves and lines.

If you haven’t converted to drip, check overhead spray for broken lines and heads, pushed-over or misdirected heads, etc.

• Collect water as it warms in your shower or sink. Use that water on plants that need a little more.

• In the vegetable garden:

Water soil, not leaves. Wet leaves are susceptible to diseases such as powdery mildew.

Water early in the morning. Check the soil before you water. The goal is to keep the soil evenly damp, but not wet.

Mulch with a 3-inch layer of straw (not hay) to slow water loss.

• For ornamental plants, determine water need on a bed-by-bed basis:

Run the water long enough to saturate the soil. Use your fingers or a soil probe to determine when the soil is wet several inches deep. Mark your calendar.

Leave the water off until the top two or three inches are dry. How many days did it take? That tells you how often that garden bed needs irrigation.

Next, in each bed, turn the water on and let it run. Check every 15 minutes to see how long it takes to rewet the soil. That tells you how long to run the irrigation for that bed every time you water.

Watch for runoff, which is a sign that soil is fully saturated. Turn off the water before there’s runoff.


Spiders eat many common pests.

Snakes and spiders might inspire nightmares, but they are very valuable garden critters.

• Spiders eat many common garden (and household) pests such as gnats, mosquitoes, aphids, wasps, leafhoppers, even june bugs.

• Gopher snakes eat gophers. Rattlesnakes eat rabbits, gophers and squirrels. King snakes eat rodents, too.

• Tiny bug bites around your ankles and legs during the day could be from Aedes mosquitoes. These tiny insects lay their eggs in small puddles of standing water indoors and out. Inspect your property weekly. Empty the dishes under your potted plants. Add mosquito fish to ponds. Screen, then securely close rain barrels to keep mosquitoes from breeding there. And remember to welcome the spiders that eat mosquitoes!

Nan Sterman is a garden designer and writer and host of “A Growing Passion” on KPBS television. For more information, visit and