Carbon Heirloom Tomato Seeds

Bring rich flavor and dusky color to your summer table with Carbon. This open-pollinated heirloom bears meaty beefsteak tomatoes with dark olive shoulders blending into rosy-brown to deep brick-red skin. Cut a ripe fruit for thick sandwich slices or pair it with yellow tomatoes for a colorful garden platter.

Why Grow Carbon?

• Distinctive dark fruit: Round to blocky, slightly flattened beefsteaks have natural variation in shoulder color and shape, rather than uniformly black skin.
• Rich fresh-eating flavor: Sweetness and tang complement the juicy, meaty texture.
• Substantial slicers: Many suppliers describe approximately 10–14 oz fruit; individual tomatoes can be smaller or larger.
• Indeterminate vines: Sturdy support helps manage ongoing growth and successive harvests during favorable weather.
• Two packet options: Choose approximately 25 or 50 seeds.

Planting and Growing

Start seeds indoors 6–8 weeks before your intended transplant date. Sow approximately ¼ inch deep in seed-starting mix, provide warmth for germination, and give seedlings strong light. Harden off gradually before planting outdoors after frost danger has passed and soil has warmed.

Choose full sun and fertile, well-drained soil. Install sturdy stakes, cages, or a trellis at planting time. Water consistently at soil level, mulch to conserve moisture, and maintain airflow while retaining healthy foliage to shade developing fruit.

For square foot gardening, use 1 plant per sq ft (trellis required) with dedicated vertical training and regular pruning. Allow more room for caged or multi-stemmed plants.

Harvest Details

Maturity: Approximately 80 days from transplant; published estimates and growing conditions vary.
Fruit: Dark brick-red to rosy-brown beefsteaks with olive shoulders, typically around 10–14 oz with natural variation.
Growth habit: Indeterminate, regular leaf; sturdy support required.
Botanical name: Solanum lycopersicum.
Life cycle: Frost-tender warm-season annual.
Packet options: Approximately 25 or 50 seeds.

Check for mature brick-red color on the less-green portions and a slight give under gentle pressure. Olive shoulders can remain at ripeness, so do not wait for the whole fruit to turn uniformly dark. Pick progressively and handle gently.

Some suppliers report reduced cracking and cat-facing compared with other dark tomatoes, but this is not a guarantee of blemish-free fruit or disease immunity. Consistent moisture and suitable growing conditions remain important.

Packed and shipped by Box Garden Seeds LLC — heirloom seeds grown without GMOs, selected for flavor and your garden's success.