Garnet Sweet Potato

A dark red-skinned sweet potato with vivid orange, moist flesh that becomes very creamy and sweet when baked. Commonly mislabeled as a yam in American grocery stores, Garnet is actually a soft-fleshed sweet potato variety. Plants produce vigorous vines that can be used as ornamental ground cover in the landscape. The high beta-carotene content gives the flesh its intense orange color and boosts nutritional value.

Grow slips from a Garnet sweet potato about eight to ten weeks before the last expected frost. Suspend the tuber in a jar of water in a warm, bright location, or nestle it halfway into moist potting mix. Sprouts appear in two to four weeks. When slips reach six inches tall with several leaves, twist them off and root in water for one week before transplanting. Each tuber can produce 10 to 15 slips. Plant outdoors only when soil temperatures have been above 65 degrees for at least a week.

The Season Plate

Your Garnet Sweet Potato Year

Composed for Zone 7 · typical seasons · frost passes Apr 2, returns Nov 1

Sow Garnet Sweet Potato May – Jun, pick Sep – Oct. Set your climate below and every date on this plate re-times itself.

Sowing window

May – Jun

re-timed to your frost dates

Plant out

after Apr 2

once frost risk has passed

First picking

around Sep 2

≈ 110 days from sowing · 1.5-3.5 kg per plant

Composed for —ColdTemperateMildWarmUse my locationUsed once to set your season · only the zone is kept

Week-by-week Garnet Sweet Potato reminders watering, feeding and pruning, timed to your dates

In the app

Frost alerts for your garden a warning before a cold night costs you the crop

In the app

Succession sowing dates so the picking never gaps mid-season

In the app

Keep my dates — free for 7 daysWe nudge you as each window opens · cancel anytime

Garnet sweet potatoes require warm growing conditions with soil temperatures above 65 degrees Fahrenheit. Plant slips outdoors after the last frost in raised mounded rows 8 to 12 inches high and 36 inches apart for excellent drainage and warmth. Space slips 12 to 18 inches apart, burying the lower portion so only the top few leaves remain exposed.

These vigorous growers produce dark red-purple vines that spread aggressively, making them effective living mulch. Water consistently during the first three weeks while roots establish, then taper off as vines run. Sweet potatoes are surprisingly drought-tolerant once established. Avoid excessive nitrogen which pushes vine growth at the expense of tuber formation. A single application of potassium-rich fertilizer at midseason supports root development.

Garnet takes about 110 days to mature, slightly longer than Beauregard, so northern growers should use season-extension techniques. Black plastic mulch pre-warms the soil and maintains heat throughout the season. Row covers provide frost protection during cool nights. Monitor soil temperature rather than calendar dates to determine planting time, as premature planting leads to poor establishment.

Garnet sweet potatoes pair well with corn and pole beans where the vines serve as ground cover beneath taller crops. The dense vine coverage shades out weeds effectively. Plant aromatic herbs like thyme and sage nearby to confuse pest insects. Avoid growing near squash and melons that compete for ground space. Sweet potatoes should not follow nightshades in crop rotation to prevent shared disease issues.

The Society Table

Corn belongs beside it.

Old growers' knowledge, checked against Garnet Sweet Potato's real companion table below — test any plant you're growing.

Grows well in the company of · 2

CornGreen Beans

Keep apart · 0

no recorded foes

Plant Garnet Sweet Potato with good neighboursThe planner flags conflicts before they're in the ground

Garnet sweet potatoes thrive in loose, sandy, well-drained soil with a pH of 5.8 to 6.2. Build raised beds or mounded rows to improve drainage and warm the root zone. Avoid heavy clay which causes misshapen tubers and promotes rot. Do not over-fertilize, especially with nitrogen, which produces lush vines but few tubers. Apply a low-nitrogen fertilizer like 5-10-10 at planting. Side-dress with potassium-rich amendments at midseason.

Ideal Temperature

Hardiness Zone Compatibility

Garnet sweet potatoes are ready about 110 days after planting, or when vines begin to yellow. Use a garden fork to carefully loosen soil, working from the edges inward to avoid damaging tubers. The dark red skin bruises easily when fresh, so handle with care. Lay freshly dug tubers on the soil surface to air-dry for a few hours. Do not wash until ready to use. Harvest before frost as cold-damaged tubers rot quickly in storage.

Storage & Preservation

Cure Garnet sweet potatoes immediately after harvest in a warm, humid environment at 80 to 85 degrees with 85 to 90 percent humidity for 10 to 14 days. This heals wounds, develops flavor, and extends storage life. After curing, store at 55 to 60 degrees in a dark, ventilated area. Properly cured roots keep four to six months. Bake, mash, and freeze in portions for up to six months. Dehydrated sweet potato slices make excellent shelf-stable snacks.

Troubleshooting Common Problems

The most common issue in northern gardens is insufficient heat units, producing small or few tubers. Use black plastic mulch and row covers to maximize warmth. Cracking occurs from uneven watering, particularly heavy rain following dry conditions. Failure to cure results in bland, starchy roots with poor keeping quality. Garnet vines grow extremely vigorously and can overwhelm small garden spaces.

Growing Tips

1. Grow your own slips to save money and ensure disease-free starts. Suspend a healthy organic Garnet sweet potato in a jar of water using toothpicks, with the bottom third submerged. Place in a warm, bright location and change water every 2-3 days. Each tuber produces 8-12 slips in 4-6 weeks.
2. Build raised mounds or ridges of loose, well-drained soil at least 25 cm high for planting. Sweet potatoes develop misshapen, undersized tubers in heavy or compacted soil. Mix in coarse sand and compost to create the ideal loose, friable texture that allows tubers to expand freely.
3. Use black plastic mulch to warm soil before planting and maintain heat throughout the season. In cooler zones (5-7), this technique can add the equivalent of 2-3 weeks to your growing season by raising soil temperatures 3-5°C above ambient — critical for a crop that needs 100-120 frost-free days.
4. Do not over-fertilize, especially with nitrogen. Excess nitrogen produces enormous, lush vines but small, spindly tubers. Apply a single side-dressing of low-nitrogen fertilizer (5-10-10) about 4 weeks after transplanting and then stop feeding entirely.
5. Lift and redirect spreading vines back toward the center of the bed every 1-2 weeks. Vines that root at nodes along the surface produce small tubers at each rooting point instead of concentrating energy into the main root cluster, significantly reducing your usable harvest.
6. Harvest on a dry, sunny day after vines have begun to yellow naturally, usually 100-120 days after transplanting. Use a garden fork inserted 30 cm from the plant center and lever tubers up gently — never pull vines to extract tubers as this snaps them and causes storage rot.
7. Curing is not optional — it is the single most important step for flavor and storage life. Freshly dug sweet potatoes taste starchy and bland. Curing at 27-32°C (80-90°F) with 85-90% humidity for 10-14 days converts starch to sugar, heals skin wounds, and enables storage for up to 12 months.
8. Never refrigerate sweet potatoes. Cold temperatures below 10°C (50°F) cause chilling injury that converts sugars back to starch, creates an unpleasant hard core in the center, and dramatically shortens storage life. Store cured tubers at 13-15°C (55-60°F) in a dark, ventilated location.