How to Grow Black Krim Tomatoes (Even in Small Spaces!)

Ever wondered if it’s possible to grow Black Krim tomato plants in pots? Well, the truth of the matter is that it is not as hard as some people make it out to be, once you take care of the key aspects. With this easy-to-follow guide you’ll have bountiful harvest in no time!

Black Krim tomatoes can be grown with

  • 7–15 gal plastic pots
  • Well-draining nutrient-rich soilless potting mix
  • Around 75–150 oz of water per week
  • 6–8 hours of full sunlight
  • Temperatures around 60–90°F
  • Humidity within 40–70%
  • Complete fertilizer every 2–4 weeks once fruiting

As delicious as cherry tomatoes can be, nothing beats the sizable dark-colored fruits of Black Krim. Despite their names though, their skin color can vary greatly depending on the light they get! Keep scrolling to find out more!

Black Krim Tomato Care Guide Table (Ready to Print!)

Common NameBlack Krim tomato
Scientific NameSolanum lycopersicum ‘Black Krim’
Perennial/AnnualPerennial in warm weather
Annual due to harsh winters
Planter7–15+ gallon plastic pot
Soil CompositionWell-draining rich potting mix or loamy soil
5.8–6.8 pH
Watering75–150 oz of water per week
Daily only for very hot & dry summer days
LightFull sun for 6–8 hours
Grow light for 14–18 hours
FertilizerComplete fertilizer 1–2 times a month
(Spring to summer)
Pest NameAphids
Cabbage loopers
Flea beetles
Potato beetles
Sap beetles
Tomato fruitworms
Disease NameAlternaria stem canker
Bacterial spot
Blossom-end rot
Early blight
Fusarium wilt
Late blight
Root-knot nematodes
Septoria leaf spot
Tobacco mosaic virus
Verticillium wilt
Care Guide for Black Krim Tomato Plants
Simple Black Krim Care Guide – Infographic
Simple Black Krim Care Guide – Infographic

1. Planter

Start young Black Krim tomato plants in pots that are at least 12 inches (30 cm) in depth and width. However, more mature plants should be in 10–15 gal containers to ensure a high yield of medium to large fruits. Plastic is best for retaining moisture.

Here’s the deal—virtually all tomato varieties can actually be grown in containers. However, indeterminate tomatoes such as Black Krim require larger planters to ensure good growth.

If space is an issue, a 10-gal plastic container will suffice. Worried about retaining too much water in the soil? Clay pots and fabric grow bags (here on Amazon) are also great options.

Keep your eyes out for molding on grow bags!

Keep in mind that the smaller the pot they’re kept in directly affects the size of the fruits they produce. Black Krim tomatoes grown in 10-gallon containers will produce bigger fruits than those kept in 7-gallon pots.

Great Container Tomatoes: The 'Black Krim' Heirloom - The Rusted Garden 2013

Work with the space you have. Some people even use old wine barrels and plastic water storage containers. Don’t forget to clean them up thoroughly before you plant your tomatoes in them though!

If you’ve got empty raised beds, they’ll grow great in those as well. Space them apart by at least 18 in (approx. 45 cm) as they can grow to widths of 3–4 ft (approx. 90–120 cm).

Also, make sure that your growing container has sufficient drainage holes at its base. Otherwise, your Black Krim tomato can die in just a couple of days from getting waterlogged.

2. Soil

Use a well-draining soilless potting mix when growing Black Krim tomatoes in containers. When growing them directly in the ground, amend the soil so that it is slightly acidic, rich in organic matter, and doesn’t get compact easily.

For what soil will work best, it’s the same for pretty much any other tomato variety.

Tomatoes grow best in slightly acidic soil that’s highly fertile. This allows it to produce Black Krim tomatoes as big as 16 ounces.

Ideal components to look for in packaged soilless potting mixes for container-grown Black Krim tomatoes include perlite, peat moss, coco coir, and vermicast.

Such ready-to-use potting mixes typically come with slow-release fertilizers as well—but more on that later. This potting soil from Amazon is a favorite among my friends.

These growing mediums make it so that there’s enough moisture in the soil for a long period and it doesn’t dry up too fast. At the same it, it can still drain freely to get rid of excess water.

Pro Tip: For in-ground cultivation of Black Krim tomato plants, remember to test and amend your soil 6–12 months in advance for soil improvement to fully take effect.

Even though Black Krim tomatoes prefer pH values between 5.8 and 6.8, they can also tolerate pH as low as 5.5 and as high as 7.

3. Watering

Black Krim tomato plants need about 1–2 inches or 75–150 oz of clean fresh water per week while it’s actively growing and producing fruits. Water them directly through the soil early in the morning to allow them to efficiently absorb moisture.

Tomatoes are made up of about 95% water. Black Krim tomatoes can weigh as much as 16 oz per fruit with proper care.

Why Watering Consistently is Important for Black Krim Tomatoes
Why Watering Consistently is Important for Black Krim Tomatoes

Simply put, watering Black Krim tomato plants consistently is important for the development of its big juicy fruits. Thus it’s important to keep the soil moist enough while the plants are forming fruits.

However, this doesn’t mean that you should keep their soil soggy at all times. Just water them whenever the top inch or so starts drying out.

Rainfall is included in the count when we talk about water. So if you’ve got your Black Krim tomatoes outdoors—in pots or soil—you can skip watering after a rainy day.

Pro Tip: Take the season into consideration too. Tomatoes grow more actively during the warmer spring and summer months than they do in the cooler fall and winter months. Water them more frequently during the growing season, and hold back for the rest of the year.

Letting their soil dry out for too long in between watering will cause Black Krim tomatoes to crack or split. At best, this will make your tomato ugly; at worst, pests and pathogens can enter through such openings and destroy not only your fruits but the entire plant too!

4. Light

Outdoor container Black Krim tomatoes need at least 6 hours of full sun exposure for plant development and fruit production. Indoors, they can be grown with a full-spectrum grow light with at least 20 Watts of power.

Without enough light, Black Krim tomatoes will abundantly grow medium and large-sized beefsteak fruits. If such conditions are prolonged, the plant will also be weak and spindly.

Light is also the primary factor affecting the darkness of Black Krim tomato skins.

Getting less than 6 hours of direct light, Black Krim tomatoes will remain mostly red in color. They may not even form dark shoulders in such growing conditions.

The longer Black Krim tomatoes are exposed to full sunlight, the deeper their colors and richer their flavor profile become. Only with such long exposure to strong light can their fruits turn almost Black.

In reality, however, Black Krim tomatoes range from dark browns, violets, greens, and reds. With such deep shades, they can indeed seem incredibly dark.

Check out other cool violet tomato varieties!

Now, don’t fret if you’re planning on cultivating Black Krim tomatoes indoors. You can always use a full-spectrum grow light that’s strong enough. I mostly use the 36W one below which you can also get on Amazon.

Position it about 6–12 inches above the topmost growth of the mature plants or 4–6 inches for seedlings. Then keep it on for more or less 14–16 hours or 16–18 hours, respectively.

5. Temperature

Whether grown indoors or outdoors, Black Krim tomato plants thrive with temperatures between 60–90°F (16–32°C). It becomes relatively heat-tolerant once established but can’t withstand frost and temperatures below 55ºF (13ºC).

Because tomatoes are naturally warm-season plants, it’s no surprise that temperature can greatly affect their productivity.

Friends and experts I know living up north, say Massachusetts, have significantly poorer yields compared to those who grow Black Krim tomatoes in states down south like Texas.

In other words, you can easily grow Black Krim tomatoes as an annual in your vegetable garden if you live in a region with tropical or subtropical climates.

Just to further explain, let’s consider Florida. There, you won’t really get to experience all four seasons—winter, spring, summer, and fall. Instead, you only have two—wet and dry.

Seasons and the Lifespan of Black Krim Tomatoes
Seasons and the Lifespan of Black Krim Tomatoes

This means that your tomato plants are likely to continue thriving even as the cooler months start. Moreover, since they’re indeterminate, they can produce fruits pretty much all year!

Forgot the differences between the two? Review them in our article on bush vs vine!

Conversely, they can only be grown as annuals outdoors in areas with harsh winter weather. That is unless you’ve got a space for a little greenhouse or a grow tent.

6. Humidity

Humidity levels within 40–70% can help Black Krim tomato plants form full and firm fruits. Prolonged exposure to high humidity levels with low ventilation can lead to mold and disease development which can lead to reduced yield and even plant death.

Quite frankly, this is not based on an exact science. This is simply my recommendation based on my and other people’s experiences in growing different tomato varieties.

If you live in a dry and cool area like Colorado, boost the humidity around your growing Black Krim tomato plant. This will help you prevent its fruits from shriveling up due to the lack of moisture in the soil and air.

By contrast, when you live in a warm but humid region, try to keep the levels moderately low to prevent molding, such as white mold, and the onset of various conditions, like blight.

What is an heirloom tomato, anyway?

As it is an heirloom variety, the Black Krim tomato is much more prone to being infected by a wide variety of bacterial, fungal, and viral diseases compared to disease-resistant hybrids.

So using a hygrometer or thermo-hygrometer like this one from Amazon will help you monitor and control the humidity around your Black Krim tomato plant much more readily.

7. Fertilizer

Apply a complete fertilizer that’s either balanced or rich in phosphorus and potassium for a bountiful harvest of big Black Krim tomatoes. Repeat feeding every 2–4 weeks in spring and summer. Don’t feed it in winter when it doesn’t grow actively.

Remember, a Black Krim tomato plant is a vining variety. This means it can continue putting out new growth and fruits as long as the weather permits.

Black Krim tomatoes are also more finicky than hybrid tomatoes so they need to be fertilized regularly for them to become productive.

For you to have a bountiful harvest of its big fruits, you need to continuously apply a high-quality fertilizer that contains all the essential nutrients it needs.

How to Fertilize Tomato Plants | Which Is Best?

What you have to check, in particular, is the NPK ratio—standing for nitrogen, phosphorus, and potassium.

Avoid going for fertilizers with excessively high nitrogen content. Sure, this would speed up and improve the vegetative growth of Black Krim tomato plants. However, it won’t induce fruit production.

Pro Tip: Instead, look for tomato fertilizers or ones that are formulated to have more phosphorus and potassium. Examples include 6-12-18 and 8-16-16 NPK.

Only start feeding your Black Krim tomato once it begins fruiting. Carefully read the instructions for the application so you don’t end up overfertilizing and killing your pant.


When should you transplant Black Krim tomato plants?

Black Krim tomato seedlings started indoors should only be transplanted outdoors to a large pot or into the garden soil once nighttime temperatures are consistently above 50–55ºF (10–13ºC) and the dangers of the last spring frost have passed. They should be slowly hardened off, including reduced watering, beforehand to ensure their survival outside.

How do you support Black Krim tomato plants?

A Black Krim tomato plant can grow to heights of 6 ft (approx. 180 cm) and above so it requires a sturdy support structure such as a cage, stake, or trellis to keep its big fruits safely off the ground. Regardless of the specific structure, it should be added during transplanting to avoid disturbing or damaging the developing root system too much.

Do you need to prune Black Krim tomato?

Regularly pruning off suckers growing by the sides of 1–3 main stems is necessary to improve air circulation, prevent fungal growth, manage pests, increase productivity, and hasten the ripening of Black Krim tomatoes. It allows the plant to focus its resources on growing bigger tomatoes than producing more shoots and leaves.

Should you mulch Black Krim tomatoes?

Black Krim tomato plants can benefit from mulching early in summer to help them retain moisture for a longer period despite the hotter weather. Adding 2–4 inches (approx. 5–10 cm) of straw, coco peat, bark chips, grass clippings and similar materials on top of the soil can also help keep its soil cool enough and suppress weed growth.

Summary of How to Grow Black Krim Tomatoes

Grow Black Krim tomatoes in small spaces indoors using 7–15 gal plastic pots, well-draining fertile soilless potting mix, 75–150 oz of water each week, 14–18 hours of 20W+ full-spectrum grow light, temperatures at 60–90°F, humidity around 40–70%, and complete fertilizer application every 2–4 weeks, starting from fruit set.

Black Krim tomato plants can also be grown outdoors as perennials provided that the gardener is in a tropical or subtropical region. Watering may be increased during especially hot summers and light exposure could be reduced to 6–8 hours under full sun.


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