Heirloom

Garnet Giant

Brassica juncea

Wikimedia Commons

Harvest

21d

Days to harvest

📅

Sun

Full sun to partial shade

☀️

Zones

8–11

USDA hardiness

🗺️

Height

12-18 inches

📏

Planting Timeline

Zone:

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Direct Sow

Harvest

Direct Sow

Harvest

Showing dates for Garnet Giant in USDA Zone 7

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Zone Map

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Garnet Giant · Zones 8–11

What grows well in Zone 7? →

Growing Details

Difficulty

Easy

Spacing6-12 inches

SoilWell-drained, fertile soil with moderate organic matter

WaterHigh — consistent moisture needed

SeasonWarm season annual

FlavorMild, delicate flavor with tender leaves suitable for fresh salads and preparations.

ColorDeep purple with green undertones

Zone-by-Zone Planting Calendar

Zone	Indoor Start	Transplant	Direct Sow	Harvest
Zone 3	—	—	May – June	May – October
Zone 4	—	—	April – June	May – October
Zone 5	—	—	April – May	May – November
Zone 6	—	—	April – May	April – November
Zone 7	—	—	March – May	April – November
Zone 8	—	—	March – April	March – December
Zone 9	—	—	February – March	February – December
Zone 10	—	—	January – March	February – December
Zone 1	—	—	June – July	June – September
Zone 2	—	—	May – July	June – September
Zone 11	—	—	January – February	January – December
Zone 12	—	—	January – February	January – December
Zone 13	—	—	January – February	January – December

Succession Planting

Garnet Giant reaches harvest in about 21 days from direct sow, which makes it one of the easier crops to succession-plant. Put in a new 3–4 foot row every 14 days starting when soil temperature hits 50°F in early spring, and keep sowing until daytime highs are consistently above 85°F — past that threshold the leaves toughen and the heat-sharpened flavor stops being pleasant. In zones 8–11, pick back up with a fall run starting in late August or early September, sowing every 14 days through October.

Don't try to bridge the summer gap by moving to a shadier spot. Heat stress on Brassica juncea is driven by soil and air temperature, not light levels — plants in 90°F weather bolt and turn bitter regardless of how much shade they're getting. Stop sowing in June, let the bed rest, and come back to it in fall.

Complete Growing Guide

Broad purple leaves with gently scalloped margins. Color appears early on young leaves, especially in spring and fall. Mild flavor. Somewhat quick to bolt. Plant densely so leaves remain a proper size for baby leaf and petioles elongate for easy harvest. Also available in organic seed. According to Johnny's Selected Seeds, Garnet Giant is 21 baby; 45 full size to maturity, annual, open pollinated. Notable features: Cold Tolerant, Hydroponic Performer.

Light: Full sun (6 or more hours of direct sunlight a day), Partial Shade (Direct sunlight only part of the day, 2-6 hours). Soil: High Organic Matter. Soil pH: Neutral (6.0-8.0). Drainage: Good Drainage, Moist. Height: 1 ft. 0 in. - 1 ft. 6 in.. Spread: 1 ft. 0 in. - 1 ft. 6 in.. Spacing: Less than 12 inches. Growth rate: Rapid. Maintenance: Medium. Regions: Coastal, Mountains, Piedmont.

Harvesting

Garnet Giant reaches harvest at 21 baby; 45 full size from sowing per Johnny's Selected Seeds. As an annual, harvest continues until frost ends the season.

Long pods with round, brown seeds. The fruits will dry and split when ripe. The seeds are harvested for use in condiments and oil.

Color: Brown/Copper. Type: Siliqua.

Garden value: Edible

Edibility: The leaves, seeds, flowers, and stems of this mustard variety are edible raw or cooked. Harvested leaves can be stored in the fridge for 3-5 days.

Storage & Preservation

Harvest Garnet Giant at peak tenderness around day 21 and refrigerate immediately in a perforated plastic bag at 32–40°F with 95% humidity. Fresh leaves will keep for 5–7 days before wilting noticeably. For longer storage, freeze blanched leaves in ice cube trays with a little water—this preserves color and works well for cooking applications, though texture won't suit fresh salads afterward. Fermentation is viable; pack shredded leaves with salt (2–3% by weight) in a jar, weight down, and let sit 3–5 days at cool room temperature for a tangy condiment. Drying is less practical for this tender variety, as the delicate burgundy leaves lose appeal quickly. A useful tip: harvest in early morning when leaves are crisp and hydrated, which extends shelf life by a day or two compared to afternoon picking.

History & Origin

Garnet Giant is open-pollinated, meaning seed saved from healthy plants will produce true-to-type offspring. Listed in the Johnny's Selected Seeds catalog.

Origin: Russia to central Asia

Advantages

+Stunning purple foliage appears early, especially in cool seasons
+Mild flavor appeals to diverse palates and pairs with many dishes
+Quick 21-day maturity enables frequent succession planting
+Scalloped leaves and elongated petioles facilitate easy, attractive harvesting
+Dense planting keeps leaves properly sized for baby leaf market

Considerations

-Somewhat quick to bolt limits harvest window in warm weather
-Requires dense spacing for optimal leaf size and appearance
-Purple coloration may fade in intense summer heat

Companion Plants

Marigolds are worth planting near Garnet Giant — not as a vague "pest repellent," but because French marigolds (Tagetes patula) planted densely are a documented cultural tool against soil nematodes. NC State Extension specifically recommends a solid planting of French marigolds to draw down nematode populations before returning susceptible crops to a bed. Radishes are useful for a different reason: they germinate in 5–7 days and mark the row while the mustard greens are still getting started, and their pungent root compounds can throw off aphids and flea beetles looking for a brassica to land on. Chives and garlic work similarly — sulfur compounds in the foliage make the surrounding 12–18 inches less hospitable to soft-bodied pests.

Fennel is the one to leave out of the picture entirely. It releases allelopathic compounds from both roots and foliage that stunt nearby plants, and brassicas pick up that inhibition faster than most. Broccoli is a different kind of problem — not chemistry, just competition. Two heavy-feeding brassicas at the same 12-inch root depth in the same bed will both come up short on nutrients. Give Garnet Giant its own section of the bed.

Plant Together

Marigolds

Repels nematodes and various garden pests through scent

Basil

Repels aphids and whiteflies, may improve lettuce flavor

Chives

Deters aphids and other soft-bodied insects that damage lettuce

Carrots

Deep roots don't compete with shallow lettuce roots, maximizes space usage

Radishes

Quick harvest frees space, helps break up soil for lettuce roots

Nasturtiums

Acts as trap crop for aphids and cucumber beetles

Spinach

Similar growing requirements and harvest timing, efficient space usage

Garlic

Natural pest deterrent, repels aphids and slugs

Keep Apart

Broccoli

Large plants create excessive shade, stunting lettuce growth

Fennel

Allelopathic properties inhibit growth of most garden plants including lettuce

Sunflowers

Tall plants create too much shade and compete heavily for nutrients

Nutrition Facts

Protein

0.742g(1%)

Carbs

3.37g(1%)

Fat

0.0738g(0%)

Vitamin K

20.5mcg(17%)

Iron

0.0332mg(0%)

Calcium

14.2mg(1%)

Potassium

139mg(3%)

Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #2346388)

Pests & Disease Resistance

Common Pests

Aphids, slugs, snails, flea beetles

Diseases

Downy mildew, lettuce mosaic virus, botrytis (gray mold)

Troubleshooting Garnet Giant

What you'll see, why it happens, and what to do about it.

Seedlings collapse at soil level within the first 7–10 days after sowing — stem looks pinched or water-soaked at the base

Likely Causes

Damping off — a fungal complex (commonly Pythium or Rhizoctonia) that thrives in cold, wet, poorly drained soil
Overwatering or soil that stays saturated after germination

What to Do

1.Pull the dead seedlings and check the soil: if you see fuzzy whitish mold on the surface, the bed is staying too wet — ease off irrigation and improve drainage before resowing
2.Direct sow into fresh, well-drained mix rather than reusing soil from a bed where you've had this problem before
3.If you're starting in trays, bottom-water only and let the surface dry slightly between waterings

Leaves develop small, irregular holes — sometimes a shotgun-scatter pattern — especially on younger foliage in spring and fall

Likely Causes

Flea beetles (Phyllotreta spp.) — tiny, jumping black beetles that feed aggressively on brassica leaves
Slugs or snails — similar damage but usually concentrated near soil level and accompanied by slime trails

What to Do

1.Cover the bed with row cover immediately after sowing — flea beetles find plants by sight and smell, and exclusion is more effective than spraying
2.For slugs, scatter iron phosphate bait (Sluggo) around the base of plants at dusk; reapply after heavy rain
3.Keep the bed clear of debris and standing water, which give slugs daytime cover

Frequently Asked Questions

How long does Garnet Giant lettuce take to harvest?▼

Garnet Giant lettuce is ready to harvest in approximately 21 days from planting. For baby leaf harvesting, you can begin picking outer leaves even sooner. Timing varies slightly depending on temperature and light conditions, with faster growth in warmer weather.

Is Garnet Giant lettuce good for beginners?▼

Yes, Garnet Giant is an excellent choice for beginners. It's classified as an easy-to-grow variety with minimal care requirements. The main consideration is that it bolts relatively quickly in heat, so planting in spring or fall and providing some afternoon shade in summer helps extend the harvest window.

Can you grow Garnet Giant lettuce in containers?▼

Absolutely. Garnet Giant grows well in containers as long as they have adequate drainage. For optimal baby leaf production, plant densely in shallow containers (6-8 inches deep). Containers allow better control of soil moisture and can be positioned to receive partial shade during hot months, which helps prevent early bolting.

What does Garnet Giant lettuce taste like?▼

Garnet Giant has a mild, delicate flavor that makes it ideal for salads and fresh preparations. The broad purple leaves are tender and the slightly elongated petioles add textural interest. Unlike more bitter varieties, its gentle taste appeals to diverse palates.

When should I plant Garnet Giant lettuce?▼

Plant Garnet Giant in spring as soon as soil can be worked, or in late summer for a fall crop. It thrives in cool seasons and color development is especially vibrant in spring and fall. Avoid planting during peak summer heat, as high temperatures encourage bolting and reduce quality.

Why should I plant Garnet Giant densely?▼

Dense planting serves multiple purposes: it keeps leaves at a proper size for baby leaf harvesting, allows petioles to elongate for easier picking, and creates a fuller, more attractive appearance. Thinning to proper spacing results in larger individual leaves if you prefer full-size plants instead.