Black Krim tomatoes are a flavorful heirloom variety that ranges from dark maroon to nearly black, with a squat, flattened globe shape and fruit that runs 4 to 6 inches across. The variety is a cross between ‘Beefsteak’ and ‘Cherokee Purple’ and originated on the Crimean peninsula along the Black Sea. Gardeners grow it for a taste that is intensely tomato-like: sweet, acidic, and slightly salty. The common tomato growing mistakes show up fast with heirlooms, so site, water, and support matter from day one.
The plant is a study in contrasts. The fruit is safe and delicious, but every other part of the vine is toxic to humans and pets, a trait it shares with the rest of the nightshade family. Black Krim is an indeterminate variety, meaning it keeps growing and setting fruit until frost, which makes support and pruning essential parts of the routine. This article covers planting, care, pest management, pruning, fertilizing, and harvest, from seed to plate.
Planting Black Krim Tomatoes
Start seeds indoors six to eight weeks before the last frost, or buy sturdy seedlings from a nursery. Black Krim is one of the most rewarding tomato varieties for home gardeners because the plants are vigorous and the flavor is distinctive, though it matures later than many hybrids.
Timing and Spacing
Do not transplant until well after the last frost, when nighttime temperatures stay consistently above 50 degrees Fahrenheit. Set plants in full sun in nutrient-dense, well-draining soil, leaving 3 to 5 feet between plants. That spacing looks generous on paper and pays off in airflow, which reduces foliar disease.
Planting Depth
Tomatoes root along the stem, so plant deeply: bury the stem up to the first set of true leaves. In cool climates, plant shallow and let the soil warm, or lay the stem in a shallow trench. Deep planting produces a larger root system and more drought tolerance.
Seedlings bought from a nursery should be hardened off for a week before they go in the ground. Set them outside for a few hours each day, gradually increasing sun exposure, so the leaves thicken instead of scorching. The transplant shock that follows a sudden move costs a week of growth at the start of the season.
| Trait | Black Krim at a Glance |
|---|---|
| Days to maturity | 75 to 80 from transplant |
| Fruit size | 4 to 6 inches across, dark maroon |
| Plant height | 4 to 6 feet |
| Spread | 3 to 4 feet |
| Growth habit | Indeterminate, needs support |
| Light | Full sun, 6 or more hours |
| Soil pH | Acidic, roughly 6.0 to 6.8 |
Sun, Soil, and the Color of the Fruit
The dark skin that gives Black Krim its name is more than a curiosity. Dark fruit absorbs heat faster than light fruit, the same physics that makes black window frames a heat-gain consideration in home design: dark surfaces soak up solar energy and convert it to warmth. That extra heat helps the fruit ripen fully in cool summers, which is why the variety performs best in full sun.
Watering consistency shapes both yield and flavor. Tomatoes need about 1 to 1.5 inches of water per week, delivered steadily rather than in gulps. Fluctuating moisture is the main trigger for blossom end rot, and it also cracks fruit when a dry spell ends in a downpour. A drip line or soaker hose keeps the bed even.
Why the Fruit Turns Dark
Black Krim colors up through pigments in the skin and flesh, a process that starts at the blossom end and spreads upward. The fruit is ready to pick when the shoulders turn from green to dark bronze and the flesh gives slightly under gentle pressure. Color alone is not a reliable ripeness signal; check firmness too.
Soil and Drainage Requirements
Black Krim wants loamy, well-drained soil with a slightly acidic pH. Work compost into the bed before planting and mulch after transplanting to hold moisture and keep soil off the lower leaves.
Testing and Adjusting Soil pH
A soil test tells you where you stand. Lime raises pH and sulfur lowers it, but adjust gradually; tomatoes tolerate a fairly wide range as long as drainage is good and the bed does not stay soggy.
Managing Pests and Diseases
Heirlooms have thinner skins and less disease resistance than modern hybrids, so scouting is part of the job. The biggest chewing pest is the tomato hornworm, a caterpillar that can strip a vine overnight. Natural tomato hornworm control starts with handpicking and ends with prevention: rotate crops, inspect the undersides of leaves, and encourage parasitic wasps.
Common Diseases
Early blight, septoria leaf spot, and blossom end rot are the usual suspects. Blossom end rot is not a disease at all but a calcium and water problem; consistent moisture prevents most of it. Space plants properly, water at the base, and remove infected lower leaves to slow fungal spread.
Prevention starts at planting. Choose a site with good airflow, avoid overhead watering in the evening, and rotate the tomato bed on a three-year cycle so soilborne pathogens do not build up. Remove and discard infected foliage rather than composting it, since most blight fungi survive a cool compost pile.
Pest Watch List
- Tomato hornworm: handpick at dusk; use Bt for heavy infestations
- Aphids: knock off with a strong spray; attract lady beetles
- Cutworms: collar seedlings at transplant
- Whiteflies: yellow sticky traps in a greenhouse or tunnel
Pruning and Training the Vines
As an indeterminate, Black Krim keeps growing until frost and needs a support system. Cages, stakes, or a trellis all work, but the plant will outgrow a small cage by midsummer. Smart pruning techniques for tomato plants keep the vine productive: remove suckers at the crotch between the main stem and a side branch, and strip leaves below the first flower cluster to improve airflow.
Suckering Strategy
For a single-stem system, pinch every sucker as it appears. For a two-stem system, keep the sucker below the first flower cluster and remove the rest. More stems mean more fruit but smaller size and a denser canopy that invites disease.
Supporting the Weight
A mature Black Krim vine loaded with fruit is heavy. Use a sturdy cage with 6 inch openings or a stake-and-twine system, and tie stems loosely. Check supports after heavy rain, when the added weight of water can snap branches.
Prune on a dry morning so the wounds heal quickly. Remove any leaf that touches the soil, along with yellowing lower foliage, and keep the base of the plant open so air reaches the stem. The goal is a vine you can see through from one side, with every leaf still getting light.
Fertilizing for Flavor and Yield
Fertility drives both yield and flavor. Before planting, work composted manure or a balanced fertilizer into the bed. Through the season, the way you select and apply tomato fertilizers changes with the plant’s stage: nitrogen early, phosphorus and potassium once flowering begins.
Feeding Schedule
- At transplant: mix a balanced 10-10-10 fertilizer into the planting hole.
- Three weeks after transplant: side-dress with nitrogen for foliage growth.
- At first flowers: switch to a low-nitrogen, higher-phosphorus formula.
- Every three to four weeks after: feed lightly to sustain fruit set.
- Six weeks before frost: stop feeding so the vines harden off.
Signs of Overfeeding
Too much nitrogen produces enormous, dark vines and few flowers. If the plant is all leaves and no fruit, cut fertilizer and let the soil settle. A calcium foliar spray can address blossom end rot without pushing excess growth.
A soil test before fertilizing prevents most imbalance problems. If the test shows adequate phosphorus, skip the bloom booster and feed with a balanced formula instead; excess phosphorus binds soil minerals and shows up as nutrient deficiencies later in the season.
Harvesting and Storing
Black Krim is ready roughly 75 to 80 days after transplant, but the calendar is a guide, not a rule. Harvest when the color deepens to dark maroon, the fruit gives slightly to pressure, and the calyx is easy to remove. The flavor peaks at full ripeness, and the salty edge develops late, so do not pick early to extend shelf life.
How to Pick
Twist the fruit gently or snip the stem with pruners. Keep the calyx attached until you are ready to eat; fruit picked with the stem on stores longer and stays firmer.
Storing and Using
Keep ripe tomatoes at room temperature; refrigeration destroys texture and flavor. Use them within a few days, or freeze, dry, or can the surplus. Black Krim makes an exceptional sauce and a striking addition to any plate.
Plan for the surplus before it arrives. A single healthy Black Krim vine can produce 10 to 20 pounds of fruit across the season, so decide early whether the extras go into sauce, salsa, or the freezer. Overripe fruit still works well for cooked dishes, even when it is too soft for slicing.
Every one of these steps rests on the ground beneath the vine. Good soil composition and quality management is the foundation the rest of the season stands on: test the bed, add organic matter, and correct the pH before the first transplant goes in. Get that right, and Black Krim rewards the effort with dark, salty-sweet fruit that no supermarket tomato can approach.