Potato
Solanum tuberosum
Solanaceae · nightshade family
- Matures
- 90–120 days
- Harvest
- Once · Annual
- Sun
- 6–8+ hrs
- Spacing
- 12 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
- 12 in
- Between rows
- 30 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 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
Direct-sowWell-suited
TransplantNot 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 tubers
- Ideal soil temp
- 50–60°F
- Set depth
- 4–6 in
Sprouts between 45–80°F; happiest around 50–60°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.
Pests7
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.
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.
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.
Potato Tuberworm
- What it is
- Potato tuberworm larvae are dull white to pinkish and do not grow longer than 1/2 inch. They have dark heads.
- What you'll see
- In tomatoes, tuberworms burrow into fruit and into terminal stems, causing them to die. In potatoes, they tunnel into tubers, stalks, and leaves.
- What to do
- Damage to tomatoes, eggplant, or peppers can be avoided by not planting these crops near infested potato crops or following a potato crop in a garden. Destroy infested tubers or store them at temperatures below 52°F to prevent tuberworm development.
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.
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.
Diseases7
Bacterial Ring Rot of Potatoes
- What you'll see
- In some potato varieties bunchy or rosetted terminal leaves may appear on young plants. Terminals appear darker green than the rest of the plant.
- What to do
- Use only certified seed tubers, rotate out of potatoes for at least 1 year, and follow strict sanitation procedures when cutting seed. Periodically disinfect cutting tools in a 1% solution of calcium hypochlorite.
Bacterial Soft Rot and Blackleg of Potatoes
- What you'll see
- Symptoms of soft rot include rotted tissues that are wet, cream to tan in color, and soft. Rot begins on the tuber surface and progresses inward.
- What to do
- Avoid planting in extremely wet soil, provide good drainage, and do not overirrigate. Use high quality, pathogen-free tubers for seed and avoid excessive hilling when planting.
Common Scab of Potato
- What you'll see
- Common scab lesions are usually circular and 6 - 8 mm in diameter, but they can be smaller in early stages of development and larger if they coalesce. Lesions typically possess a raised margin and slightly depressed center.
- What to do
- Common scab is largely cosmetic; affected tubers are edible. The disease is favored by neutral to basic soil; sulfur may be worked into the soil to make it slightly acidic and thus reduce disease.
Early Blight on Potatoes
- What you'll see
- Early blight is primarily a disease of stressed or senescing plants. Symptoms appear first on the oldest foliage.
- What to do
- Early blight can be minimized by maintaining optimum growing conditions, including proper fertilization, irrigation, and management of other pests. Grow later maturing, longer season varieties.
Mosaic Viruses of Potato
- What you'll see
- Many viruses are difficult to distinguish from one another based on symptoms alone. In addition, for each particular disease, symptoms will vary greatly depending on stage of plant at time of infection and other factors.
- What to do
- Control weeds as some may serve as alternate hosts for virus. Reflective mulches or row covers may help prevent infection by aphid-transmitted viruses.
Potato Leafroll
- What you'll see
- Potato leafroll virus Plants with leafroll infections typically are stunted and may appear erect. Leaves roll upward at the margins, have a stiff leathery texture, may be chlorotic, and die prematurely.
- What to do
- Although leafroll is transmitted by aphids, control of aphids once present will not prevent disease. Use of reflective mulches to repel aphids may help.
Verticillium Wilt on Potatoes
- What you'll see
- Verticillium wilt becomes evident when lower leaves on the vine turn yellow and wither. Symptoms progress upward until the entire plant yellows and wilts.
- What to do
- Verticillium wilt is caused by a soilborne fungus. Avoid soil previously planted with tomatoes, peppers, eggplant, or cucurbits.
Sources
Every figure above is backed by these.
- UC Master Gardeners, San Mateo–SF Countiesbacks plantingWindow, startMethod · Foggy & Sunny calendars, Potato row: plant Feb-Aug (foggy), Feb-Jul (sunny). Start method: Foggy & Sunny calendars, Potato row: seed pieces planted in place.
- Golden Gate Gardening (Pam Peirce)backs plantingWindow, sunlight, lifecycle, harvestStyle · Foggier/Sunnier planting-times charts, Potato tubers: Apr-Sep (foggy), Feb-Sep (sunny); GGG potato entry: full sun. Habit and harvest: annual, once — 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): potatoes.
- UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, inRowSpacing, rowSpacing, startMethod · Vegetable Planting Summary, Potatoes row: 90-120 days, 12 in in-row spacing. Between-row spacing 30 in (Potatoes row). Start method: Vegetable Planting Summary, Potatoes row: method D (usually direct-sown).
- University of Maryland Extensionbacks germination · UMD Extension: seed-potato soil floor 'at least 45°F'; 'in excess of 80°F will inhibit tuber development' (max).
- Utah State University Extensionbacks germination · USU Extension: soils 50–60°F encourage rapid sprouting and emergence (optimal).
- USDA GRIN Taxonomybacks botany
- Colorado State University Extension (Master Gardener)backs plantingDepth · Table 1 Cool Season, Potatoes row: seed-piece planting depth 4-6 in.
- NC State Extension — Plant Toolboxbacks growthHabit · Solanum tuberosum entry: Height '1 ft. 0 in. - 2 ft. 0 in.' (12-24 in), Habit/Form 'Erect, Spreading' — leafy top-growth stands upright on its own (may flop late), so upright. (Missouri Botanical Garden Plant Finder likewise caps potato at 1.0-1.5 ft, confirming the low foliage height.)
- UC Master Gardeners, Santa Clara Countybacks startMethod · Start method: Planting chart: Potatoes carry a 'Plant pieces' row only, From seed to transplant Not applicable.