Zucchini
Cucurbita pepo subsp. pepo
Cucurbitaceae · gourd family
- Matures
- 50–60 days
- Harvest
- Continuous · Annual
- Sun
- 6–8+ hrs
- Spacing
- 24–48 in
Planting window
When to sow, by microclimate — foggier blocks run a different calendar than sunnier ones.
| Jan | Feb | Mar | Apr | May | Jun | |
|---|---|---|---|---|---|---|
| Foggy | ◐ | ◐ | ● | ● | ||
| Sunny | ◐ | ● | ● | ● |
| Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|
| Foggy | ◐ | ◐ | ||||
| Sunny | ◐ | ◐ |
Well-suitedMarginalNot suited
Sunlight
How well it does at each level of direct sun per day.
<2 hrsNot suited
2–4 hrsNot suited
4–6 hrsMarginal
6–8 hrsWell-suited
8+ hrsWell-suited
Well-suitedMarginalNot suited
Soil depth
Root room it needs — useful for sizing raised beds and containers.
6–10"Not suited
10–15"Not suited
15–18"Marginal
18–24"Well-suited
Well-suitedMarginalNot suited
Spacing
Room each plant needs — along the row and between rows — for sizing beds.
- In-row
- 24–48 in
- Between rows
- 48 in
Growth habit
The shape it makes in the bed and how tall it gets — what tells you whether to give it a trellis, a stake, or just room.
- Habit
- Upright
- Mature height
- 1–2.5 ft
Stands on its own; the tallest types appreciate a stake in wind.
How to start it
Sow it where it grows, or raise it under cover and set it out — and how far ahead to start the seedlings if it's the latter.
- Usually
- Direct-sow
- Start indoors
- 4 weeks ahead
Direct-sowWell-suited
TransplantWell-suited
Sown straight into the bed it will grow in.
Well-suitedMarginalNot suited
Getting started
How it goes in the ground — how deep to sow or set it, and the soil temperature it needs to wake up. The cold-soil floor is the real limiter for direct-sowing in a foggy SF spring.
- Started from
- From seed
- Ideal soil temp
- 85–95°F
- Sow depth
- 1–1.5 in
- Time to emerge
- 5–10 days
Germinates between 60–105°F; happiest around 85–95°F.
30°F110°F
IdealWorkable
Pests & diseases
What tends to trouble this crop — what it is, what you'll see, and what to do about it, least-toxic first.
Pests14
Aphids
- What it is
- Aphids have soft pear-shaped bodies with long legs and antennae and may be green, yellow, brown, red, or black depending on the species and the plants they feed on. A few species appear waxy or woolly due to the secretion of a waxy white or gray substance over their body surface.
- What you'll see
- Low to moderate numbers of leaf-feeding aphids aren't usually damaging in gardens or on trees. However, large populations can turn leaves yellow and stunt shoots; aphids can also produce large quantities of a sticky exudate known as honeydew, which often turns black with the growth of a sooty mold fungus.
- What to do
- Before planting vegetables, check surrounding areas for sources of aphids and remove these sources. On the other hand, these aphid-infested weeds can sometimes provide an early source of aphid natural enemies.
Armyworms
- What it is
- Armyworm larvae feed in groups, which distinguishes them from other vegetable pests such as corn earworms and loopers. Markings on newly hatched armyworms are usually hard to distinguish from those of other caterpillars; older larvae have distinct lengthwise stripes.
- What you'll see
- Armyworms may feed on the crowns of seedlings. On larger plants, armyworm caterpillars skeletonize leaves.
- What to do
- Handpick. Virus diseases, parasites (Hyposoter and Trichogramma), and general predators may be effective on caterpillars.
Cucumber Beetles
- What it is
- Adult beetles are shiny with black heads, long antennae, and about 1/4 inch long. Adults may be striped or spotted, depending upon species.
- What you'll see
- Adults feed on the leaves of many vegetables as well as on soft fruit. Shoots and blossoms may also be consumed.
- What to do
- Management of cucumber beetles is difficult. The best strategy for most vegetable gardens may be to place protective cloth over emerging plants and remove it when plants are old enough to tolerate damage.
Cutworms
- What it is
- Cutworms are dull brown caterpillars ranging in length from 1 to 2 inches when fully grown. They curl into a C-shape when disturbed.
- What you'll see
- Cutworms feed on blossoms and leaves of many ornamental plants and attack most garden crops. They clip off seedling stems near or just below the soil level.
- What to do
- Cutworms are pests mainly in the spring. Destroy crop residues; keep garden weed-free in winter.
Earwigs
- What it is
- The adult earwig is readily identified by a pair of prominent appendages that resemble forceps at the tail end of its body. Used for defense, the forceps are somewhat curved in the male but straighter in the female.
- What you'll see
- European earwigs feed on a variety of dead and living organisms, including insects, mites, and growing shoots of plants. They are voracious feeders on soft-bodied insects such as aphids and insect eggs and can exert significant biological control under some circumstances.
- What to do
- Management of earwigs requires an integrated program that takes advantage of their habitat preferences. Initiate a regular trapping program.
Flea Beetles
- What it is
- Their small size, enlarged back legs, characteristic shot-hole damage, and habit of jumping when disturbed make flea beetles easy to identify. There are numerous flea beetle species.
- What you'll see
- Adults feed mostly on leaves, leaving tiny pits or small holes at their feeding sites. Flea beetles feeding together can cover leaves with bleached, pitted areas or ragged holes.
- What to do
- Remove debris in the fall to remove any overwintering beetles. Reflective mulches applied very soon after planting and before plants become infected can be helpful.
Leafhoppers
- What it is
- Leaf stippling (bleached specks) is commonly the most obvious indication that leafhoppers or certain other arthropods that suck plant juices are present. Because discolored spots or overall bleaching of leaves are also caused by lace bugs, plant bugs and other true bugs, spider mites, and thrips, examine the underside of leaves for the arthropods themselves to distinguish the cause of damage.
- What you'll see
- Leafhopper feeding causes leaves to develop pale specks (stippling). Leaves and shoot tips fed upon by an abundance of leafhoppers may turn yellow then brown and curl and die.
- What to do
- In most situations, leafhoppers are just an annoyance or curiosity and do not threaten plant survival. Leafhoppers have many natural enemies, including assassin bugs, brown lacewings, damsel bugs, green lacewings, lady beetles, minute pirate bugs, and spiders.
Loopers
- What it is
- Loopers are green caterpillars with several white stripes down their backs. They arch their backs as they crawl, this looping movement giving them their name.
- What you'll see
- Loopers eat irregular holes in leaves, most often older leaves. They may also bore holes in lettuce and cabbage heads or damage fruit.
- What to do
- Handpick. Apply Bacillus thuringiensis or spinosad; they are effective against loopers, especially when caterpillars are small.
Snails and Slugs
- What you'll see
- Snails and slugs feed on a variety of living plants and on decaying plant matter. They create irregular holes with smooth edges on leaves and flowers by scraping with their rasp-like tongues.
- What to do
- It will not be possible to eliminate some shelters, such as low ledges on fences, the undersides of wooden decks, and water meter boxes, so make a regular practice of trapping and removing snails and slugs from these areas. The survivors congregate in the remaining shelters, where you can more easily locate and remove them.
Spider Mites
- What it is
- To the naked eye, spider mites look like tiny, moving dots; however, you can see them easily with a 10X hand lens. Adult females, the largest forms, are less than 1/20 inch long.
- What you'll see
- Mites cause damage by sucking cell contents from leaves. A small number of mites usually isn’t reason for concern, but very high populations—levels high enough to show visible damage to leaves—can damage plants, especially herbaceous ones.
- What to do
- Cultural practices can have a significant impact on spider mites. Midseason washing of trees and vines with water to remove dust may help prevent serious late-season mite infestations.
Stink Bugs
- What it is
- Adult stink bugs are distinguished from other insects by the large triangle shape with a rounded rear end (scutellum) that occurs on top of the back, covering the rear of the thorax and front portion of the abdomen. In comparison with most insects, adults are wider relative to their length.
- What you'll see
- Adults suck and feed on plants with their strawlike mouthparts. Stink bugs attack a variety of fruits, nuts, and vegetables from beans to tomatoes and apples to stone fruits.
- What to do
- Handpick the bugs and their eggs from small plants. Parasites and general predators can contribute to the control of some stink bug species if natural enemies are not destroyed, such as by the application of persistent, broad-spectrum insecticides.
Thrips
- What it is
- Most adult thrips are elongate, slender, minute (less than 1/20 inch long), and have long fringes on the margins of both pairs of their long, narrow wings. Immatures (called larvae or nymphs) are oblong or slender and elongate and lack wings.
- What you'll see
- Thrips feeding on plants can damage fruit, leaves, and shoots and very noticeably affect plants’ cosmetic appearance. However, thrips rarely kill or threaten the survival of trees and shrubs.
- What to do
- Thrips species that feed on many different plant species often move into gardens and landscapes when plants in weedy areas or grasslands begin to dry in spring or summer. Avoid planting susceptible plants next to these areas, and control nearby weeds that are alternate hosts of pest thrips.
Vegetable Leafminers
- What it is
- Adult leafminers are small, active, black flies often with a prominent yellow triangle between the bases of the wings. The head behind the eyes is mostly black.
- What you'll see
- Leafminers attack many different vegetable and flower hosts, including cole crops, cucurbits, tomatoes, peas, beans, aster, begonia, dahlia, impatiens, lily, marigold, petunia, and verbena. Adult female leafminers puncture leaves and sometimes petals to feed on exuding sap.
- What to do
- Leafminers rarely require treatment in gardens. Clip off and remove older infested leaves.
Whiteflies
- What you'll see
- Whiteflies use their piercing, needlelike mouthparts to suck sap from phloem, the food-conducting tissues in plant stems and leaves. Large populations can cause leaves to turn yellow, appear dry, or fall off plants.
- What to do
- Whiteflies have many natural enemies, and outbreaks frequently occur when these natural enemies have been disturbed or destroyed by pesticides, dust buildup, or other factors. General predators include lacewings, bigeyed bugs, and minute pirate bugs.
Diseases5
Cucurbit Viruses
- What you'll see
- Potyviruses, Mosaic viruses, Cucumber aphidborne yellows, and Lettuce infectious yellows Symptoms of virus diseases include mottling of light green, yellow, or white areas on leaves, clearing of veins, thickening of leaves, and reduction in growth and yield. Fruit may be deformed.
- What to do
- Viruses are transmitted by insects, such as aphids, whiteflies, and cucumber beetles. Remove infected plants as soon as they are detected.
Downy Mildew on Cucurbits
- What it is
- Downy mildew growth may initially be confused with powdery mildew. However, the two diseases differ in several important ways.
- What you'll see
- Downy mildew attacks all cucurbits, although cucumber is the most commonly infected. It appears first as small, pale green to yellow, angular spots delimited by leaf veins that give the foliage a mottled appearance.
- What to do
- Spores of the downy mildew fungus are carried by air currents or by rain-splash or sprinklers. Avoid using overhead sprinklers.
Powdery Mildew on Cucurbits
- What you'll see
- Two species of fungi can cause powdery mildew on cucurbits: Sphaerotheca fuliginea and Erysiphe cichoracearum. S. fuliginea is the more common.
- What to do
- Control weeds and follow good sanitation practices. Avoid overhead sprinklers.
Root Rot on Cucurbits
- What you'll see
- Phytophthora spp. Root rot can occur on all cucurbits. Crown leaves turn yellow followed by a rapid collapse or wilt of the entire plant.
- What to do
- Root rot is usually more common on crops planted for a fall harvest and generally follows a period of cool or damp conditions. Plant in high, well-drained beds and avoid heavy clay soils.
Verticillium Wilt on Cucurbits
- What you'll see
- Verticillium wilt can affect all cucurbits. The first symptoms are wilting and yellowing of crown leaves, which eventually dry up.
- What to do
- Avoid planting where potatoes, peppers, eggplants, tomatoes, or cucurbits have previously been planted. Some resistant varieties are available.
Disorders1
Blossom End Rot
- What you'll see
- Blossom end rot affects tomatoes, peppers, and cucurbits. Plants with blossom end rot show small, light brown spots at the blossom end of immature fruit.
- What to do
- Blossom end rot results from a low level of calcium in the fruit and water balance in the plant. It is aggravated by high soil salt content or low soil moisture and is more common on sandier soils.
Sources
Every figure above is backed by these.
- UC Master Gardeners, San Mateo–SF Countiesbacks plantingWindow, startMethod · Foggy & Sunny calendars, "Squash, summer" row (zucchini is a summer squash): seed Mar-Jun in both microclimates. Start method: Foggy & Sunny calendars, Squash, summer row: (S) sow seed only.
- Golden Gate Gardening (Pam Peirce)backs plantingWindow, sunlight, lifecycle, harvestStyle · Foggier/Sunnier planting-times charts, "Squash, Summer": foggier Apr-Jun core (Mar/Jul maybe), sunnier Mar-Jul; edges softened to maybe where the SF calendar and Peirce disagree. GGG summer squash entry: full sun. Habit and harvest: annual, continuous (keeps yielding as you keep picking) — from this source's entry for this crop.
- UC Master Gardeners, Santa Clara County (Containers)backs soilDepth · Soil-depth-by-crop, deep-rooted (18-24 in) list names "zucchini" explicitly.
- UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, inRowSpacing, rowSpacing, startMethod · Vegetable Planting Summary, "Squash, summer" row (zucchini is a summer squash): 50-60 days, 24-48 in in-row spacing. Between-row spacing 48 in (Squash, summer row). Start method: Vegetable Planting Summary, Squash, summer row: method D/T — either, direct-sowing usual.
- UC Master Gardeners, Sacramento County (Germination)backs germination · GN 154 squash row: 60/85–95/105°F (soil temperature).
- Cornell University Home Gardeningbacks germination · Cornell Home Gardening, Summer squash guide (explicitly names zucchini) — Days to emergence: 5 to 10
- USDA GRIN Taxonomybacks botany
- Colorado State University Extension (Master Gardener)backs plantingDepth · Table 2 Warm Season, Squash Summer row: 1-1 1/2 in. (zucchini is a summer squash).
- Missouri Botanical Garden Plant Finderbacks growthHabit · Plant Finder, Cucurbita pepo (the species named as 'summer squash including crookneck, straightneck, scallop, vegetable marrow, cocozzelle and zucchini'): 'vine or bush form'; zucchini is grown as a bush -> classified upright. Listed Height 1.00-2.50 ft (12-30 in), Spread 2.00-3.00 ft. Stored height 12-30 in is the bush's own vertical extent.
- UC Master Gardeners, Santa Clara Countybacks startMethod · Start method: Planting chart: Zucchini carries both rows; From seed to transplant 4 weeks.