Potato and Tomato: Family, Nutrition & Growing Guide

Potatoes and tomatoes share a surprising botanical relationship as members of the Solanaceae family, though they offer distinct nutritional profiles and culinary applications. While both originated in South America, tomatoes (Solanum lycopersicum) provide vitamin C and lycopene, while potatoes (Solanum tuberosum) deliver potassium and complex carbohydrates. Gardeners should avoid planting them together due to shared disease vulnerabilities.

Why These Two Staples Belong in Every Kitchen (and Garden)

When you slice a ripe tomato alongside a freshly dug potato, you're holding two culinary powerhouses with a fascinating shared history. Despite their different appearances and uses, these vegetables connect through their South American origins and botanical lineage. Understanding their relationship helps home cooks and gardeners maximize flavor, nutrition, and harvest success.

Botanical Family Ties: More Than Just Nightshade Relatives

The Solanaceae family—commonly called nightshades—includes both tomatoes and potatoes along with peppers and eggplants. This relationship explains their similar flower structures and chemical compounds. While tomatoes develop above ground as fruits (yes, botanically they're fruits!), potatoes form underground as modified stems called tubers.

According to the Royal Botanic Gardens, Kew, both plants diverged evolutionarily approximately 8 million years ago. Modern genetic analysis confirms they share about 70% of their DNA sequence, explaining why certain pests and diseases affect both plants.

Nutritional Showdown: What Each Brings to Your Plate

While both provide essential nutrients, their nutritional profiles serve different dietary needs. A medium tomato (148g) delivers just 22 calories but packs 28% of your daily vitamin C and 20% of vitamin K. Potatoes (150g), meanwhile, provide 110 calories with 37% of your daily potassium and 32% of vitamin C.

Nutrient	Tomato (148g)	Potato (150g)
Calories	22	110
Vitamin C	28% DV	32% DV
Potassium	9% DV	37% DV
Fiber	2g	3g
Unique Compounds	Lycopene, Beta-carotene	Resistant starch, Chlorogenic acid

Data sourced from the USDA FoodData Central database shows tomatoes excel as antioxidant powerhouses, while potatoes provide sustained energy through complex carbohydrates. The lycopene in tomatoes becomes more bioavailable when cooked, making tomato sauce particularly beneficial.

Companion Planting: Why Gardeners Should Keep Them Separate

Despite their shared heritage, planting potatoes and tomatoes together creates significant risks. Both are vulnerable to Phytophthora infestans, the pathogen responsible for the Irish Potato Famine, which also causes tomato blight. The University of Minnesota Extension recommends maintaining at least 20 feet between plantings to prevent disease transmission.

Successful garden planning requires understanding these context boundaries:

• Rotate crops annually—never plant either in the same spot two years running
• Avoid overhead watering to reduce fungal spread
• Use physical barriers like row covers during wet seasons
• Choose disease-resistant varieties when possible

Culinary Synergy: Perfect Pairings That Work

While they shouldn't share garden space, potatoes and tomatoes create magic in the kitchen. Their complementary flavors shine in traditional dishes worldwide:

• Spanish tortilla—layers of potatoes and onions bound with eggs and tomatoes
• Indian aloo tamatar—spiced potato and tomato curry
• Italian pan con patate—roasted potatoes and tomatoes on crusty bread
• Peruvian causa—layered potato and avocado with tomato salsa

The acidity of tomatoes balances the starchiness of potatoes, creating satisfying flavor profiles. When roasting, cut potatoes slightly smaller than tomatoes since they require longer cooking time.

Common Misconceptions Debunked

Several myths persist about these vegetables:

• "Tomatoes are vegetables"—Botanically they're fruits (developed from flower ovaries), though legally classified as vegetables in the US since the 1893 Nix v. Hedden Supreme Court case
• "Potato skins are poisonous"—While green potato skins contain solanine, properly stored potatoes have safe skin levels
• "All nightshades cause inflammation"—Research from Arthritis Foundation shows no consistent evidence linking nightshades to inflammation in most people

Maximizing Your Harvest: Practical Tips

For gardeners, understanding their different growing requirements ensures success:

• Tomatoes need 6-8 hours of direct sun and consistent moisture
• Potatoes prefer slightly acidic soil (pH 5.0-6.0) and regular hilling
• Harvest tomatoes when uniformly colored and slightly soft
• Dig potatoes when foliage yellows, then cure for 10 days before storage

When storing, keep potatoes in a cool, dark place (45-50°F) but never refrigerate, as cold temperatures convert starch to sugar. Store tomatoes at room temperature until ripe, then refrigerate only if necessary to extend shelf life.

Can you plant potatoes and tomatoes in the same garden bed?

No, experts recommend avoiding planting potatoes and tomatoes together due to shared disease vulnerabilities. Both are susceptible to blight and other pathogens that can spread between them. Maintain at least 20 feet between plantings and rotate crops annually.

Why are potatoes and tomatoes in the same plant family?

Potatoes and tomatoes both belong to the Solanaceae family (nightshades) because they share a common evolutionary ancestor in South America. Genetic analysis shows they diverged approximately 8 million years ago but still share about 70% of their DNA sequence.

Which has more nutritional value, potato or tomato?

Both offer unique nutritional benefits. Tomatoes provide more vitamin C and lycopene (an antioxidant), while potatoes deliver more potassium and complex carbohydrates. A balanced diet benefits from both—tomatoes excel as antioxidant sources, while potatoes provide sustained energy.

Are potatoes and tomatoes safe to eat together?

Yes, potatoes and tomatoes are completely safe to eat together and create delicious flavor combinations in many traditional dishes worldwide. The misconception that nightshades shouldn't be combined comes from unfounded claims about 'incompatible' foods, which lack scientific evidence.