Tasmanian Chocolate Tomato

What is the Tasmanian Chocolate tomato?

Tasmanian Chocolate is a large, indeterminate heirloom tomato with deep brownish-red to mahogany skin, meaty flesh, and a rich, complex flavor profile that heirloom tomato enthusiasts rank among the best large-fruited varieties available. It originated in Tasmania, Australia, and has been grown in US home gardens since the 1990s.

At harvest, the fruit is 8–16 oz with distinctive chocolate-brown coloring and green-tinted shoulders that stay green-brown even at full ripeness. The flesh is dark red-pink, meaty, and produces less gel than many large heirlooms — making it excellent for slicing, sandwiches, and fresh eating.

Tasmanian Chocolate is classified as an indeterminate variety: it grows continuously until killed by frost, reaches 6–8 feet tall in ideal conditions, and requires substantial staking or caging. This guide covers how to grow it across US zones.

How Tasmanian Chocolate compares to similar varieties

Tasmanian Chocolate occupies a similar flavor profile to Cherokee Purple (see our Cherokee Purple tomato guide) but with a darker exterior and meatier interior. Compared to Brandywine, it matures faster and has a darker skin color.

For growers who want a large, low-acid heirloom with distinctive coloring, Tasmanian Chocolate and Black Krim are the closest competitors. Tasmanian Chocolate produces larger individual fruits and has a slightly more complex, less “smoky” flavor.

Starting from seed

When to start

Tasmanian Chocolate, like all large heirloom tomatoes, needs a long growing season. Start seeds indoors:

Start seeds 6–8 weeks before your last frost date. For Zones 3–4 with short summers, start 8 weeks ahead to give the plant maximum time to produce before the first fall frost.

Germination

Tasmanian Chocolate seeds germinate reliably at 70–85°F. Use a heat mat to maintain soil temperature — seed germination drops significantly below 65°F.

1. Fill seed cells with moistened seed-starting mix
2. Plant seeds 1/4 inch deep, 1 per cell
3. Cover tray with a plastic dome to maintain humidity
4. Germination: 5–10 days at 75–80°F
5. Remove dome and move under grow lights as soon as sprouts appear

After germination, grow seedlings under grow lights for 14–16 hours per day. Leggy seedlings (stretched stems) indicate insufficient light — lower the light source to within 2–4 inches of the plant tops.

Transplanting and early care

Hardening off

Two weeks before the transplant date, begin hardening off seedlings by setting them outside in a sheltered spot for increasing periods each day. See our guide to how to grow tomatoes from seeds for a detailed hardening schedule.

Soil preparation

Tasmanian Chocolate, like all large heirlooms, is a heavy feeder. Prepare beds with:

• 4–6 inches of compost worked into the top 12 inches of soil
• 2–3 tablespoons of balanced fertilizer (5-10-10 or similar) per planting hole
• Soil pH 6.0–6.8

Calcium is critical for large-fruited heirlooms. Calcium deficiency causes blossom end rot — a dark, sunken lesion on the bottom of the fruit. Add garden lime or gypsum to soil if calcium levels are low (your soil test will indicate this).

Transplanting

Transplant when:

• Soil temperature is 60°F or above
• Nighttime temperatures consistently above 50°F
• Seedlings are 6–10 inches tall with 2–3 sets of true leaves

Plant deep — bury the stem up to the lowest set of leaves. Tomatoes root from buried stem tissue, and a deeper root system supports the large plant better.

Space plants 24–36 inches apart. Because Tasmanian Chocolate is a large indeterminate with significant foliage, wider spacing (30–36 inches) reduces disease by improving airflow.

Support structures

Tasmanian Chocolate plants require substantial support — 5–6 foot stakes minimum, or a heavy-gauge tomato cage. Standard flimsy wire cages sold at hardware stores collapse under the weight of a mature plant.

Best support options:

• Wooden stake (1.5-inch square, 6 feet): most reliable; drive 12 inches into the ground for stability; tie plants every 8–10 inches as they grow using the Florida weave method
• Rebar cage (4-6 feet tall, 18-inch diameter): very sturdy; can be reused for years; overkill for smaller varieties but ideal for large heirlooms
• T-post with wire: commercial approach; 6-foot T-posts with horizontal cattle wire panels work for multiple plants in a row

Install support before or at transplanting — driving stakes near an established plant risks damaging roots.

Growing season care

Watering

Consistent watering is the single most important factor in preventing problems with large-fruited heirlooms.

• Weekly target: 1–2 inches of water, depending on temperature and soil type
• Method: drip irrigation or soaker hose at soil level; overhead watering promotes fungal disease
• Avoid: irregular watering causes blossom end rot and fruit cracking — the most common problems with large heirlooms

During fruit fill (when the tomatoes are sizing up), increase watering to 2 inches per week. Reduce slightly as fruits approach harvest.

Fertilizer

After transplanting:

• Weeks 2–4: no fertilizer needed; the plants are establishing roots
• First flowers appear: side-dress with a balanced fertilizer (5-10-10) or compost tea; switch to a low-nitrogen, higher-phosphorus fertilizer to support fruit set
• Every 3–4 weeks through season: continue side-dressing with compost or a balanced fertilizer

Avoid high-nitrogen fertilizer after first flowers appear — excess nitrogen pushes leafy growth at the expense of fruit production.

Pruning for large fruit

Tasmanian Chocolate produces its largest fruit when pruned to 2 main leaders (stems). This concentrates the plant’s energy into fewer, larger fruits.

How to prune:

• Remove all suckers (shoots emerging from the V between the main stem and a branch) except one — this becomes the second leader
• Allow the main stem and this chosen sucker to grow; remove all other suckers weekly
• Pinch out the growing tip of both leaders when they reach the top of your support structure (or 6 feet), 4 weeks before your first fall frost date

For higher total yield at slightly smaller fruit size, allow 3–4 leaders. A plant pruned to 4 leaders produces more tomatoes but individual fruit averages 8–10 oz rather than 12–16 oz.

For comprehensive tomato care, see our how to grow tomatoes guide. For growing in containers, see growing tomatoes in pots.

Recognizing ripeness in Tasmanian Chocolate

This is where Tasmanian Chocolate most often confuses first-time growers. The color ripeness cues are different from standard red tomatoes.

What to look for:

• The lower 2/3 of the fruit turns deep mahogany-red to dark chocolate-brown
• The upper shoulders remain greenish-brown (this is normal, even at full ripeness)
• The fruit yields to gentle thumb pressure — like a ripe peach
• The stem end may show a slight “give” at the attachment point

What not to wait for:

• Fully red color (won’t happen)
• Green shoulders to disappear (they stay green-brown in this variety)

If you wait for the color cues you’d use with Red Slicers or Early Girls, you’ll either pick Tasmanian Chocolate too early (when it’s still firm and less flavorful) or too late (when it’s begun to over-soften).

Pick fruit slightly before peak softness and ripen at room temperature for 1–2 days for the best flavor. Do not refrigerate — cold destroys the complex flavor compounds that make this variety worth growing.

Common pests and diseases

Tasmanian Chocolate is not notably more or less disease-resistant than other large heirloom tomatoes. Heirlooms as a group are more susceptible to certain diseases than F1 hybrid varieties bred for specific resistances.

Most common issues:

• Early blight and Septoria leaf spot: fungal diseases affecting lower leaves in mid-summer; remove affected leaves, mulch to prevent soil splash, water at ground level
• Blossom end rot: calcium deficiency caused by irregular watering; prevent by consistent deep watering and adding calcium to soil at planting
• Fruit cracking: caused by irregular watering or heavy rain after a dry period; mulch heavily and maintain consistent soil moisture
• Tomato hornworm: large green caterpillars that can strip foliage quickly; hand-pick and drop in soapy water; check undersides of leaves

For more pest details, see our tomato plants care guide.

Saving seeds from Tasmanian Chocolate

Because Tasmanian Chocolate is an open-pollinated heirloom (not an F1 hybrid), seeds saved from your harvest will grow plants true to type the following season.

Seed saving process:

1. Choose a fully ripe, unblemished fruit from a vigorous plant
2. Scoop seeds and gel into a glass of water
3. Let ferment at room temperature for 3 days (this removes germination inhibitors)
4. Rinse seeds in a fine-mesh strainer; remove floating seeds (non-viable)
5. Spread on a coffee filter or wax paper to dry for 1–2 weeks
6. Store in a labeled envelope in a cool, dry location; viable for 4–5 years

Saved seeds from isolated plants (no other tomato varieties within 50 feet) have the highest genetic fidelity. Cross-pollination between varieties is uncommon but possible.

Where to buy Tasmanian Chocolate seeds

Tasmanian Chocolate is not commonly available at big-box garden centers — it’s primarily stocked by specialty heirloom seed suppliers. Look for it at:

• Renee’s Garden Seeds (reneesgarden.com)
• Baker Creek Heirloom Seeds (rareseeds.com)
• Seed Savers Exchange (seedsavers.org)
• Victory Seeds (victoryseeds.com)

For a broader overview of heirloom variety selection and flavor comparisons, see our heirloom tomatoes guide and the mortgage lifter tomato article, which covers another large-fruited heirloom worth growing alongside Tasmanian Chocolate.

The USDA Agricultural Research Service tracks heirloom tomato variety evaluation in its Vegetable Crops Research Unit — a useful resource for understanding which heirlooms perform best in different US climates.