Heirloom Brandywine Tomato Seeds (Updated October 14th)

The Enduring Legacy of Brandywine Tomatoes: A Gardener’s Comprehensive Guide

Among the vast and varied world of heirloom tomatoes, the Brandywine stands as a towering giant, both in physical stature and legendary reputation. Revered by home gardeners, professional chefs, and seed savers alike, this indeterminate beefsteak tomato is synonymous with unparalleled flavor, a rich history, and the delightful challenge of nurturing an iconic plant to fruition. For many, growing a Brandywine is not merely gardening; it’s a pilgrimage into the heart of authentic tomato taste, a connection to agricultural heritage, and a testament to patience and care. This comprehensive guide delves into every facet of the Brandywine, from its mysterious origins to its meticulous cultivation, ensuring that even the most ambitious gardener can unlock the secrets to a bountiful and flavorful harvest.

Brandywine tomatoes are celebrated for their massive size, often exceeding a pound, and their distinctively creamy, rich flavor profile that perfectly balances sweetness and acidity. Unlike many modern hybrid tomatoes bred for uniform appearance, disease resistance, and shipping durability, Brandywine prioritizes taste above all else. This pursuit of flavor, however, comes with its own set of considerations, including extended growing seasons, unique foliage, and a susceptibility to some common tomato ailments. Embracing these characteristics is part of the Brandywine experience, rewarding the dedicated grower with arguably one of the finest tasting tomatoes in existence.

A Deep Dive into Brandywine’s Storied History and Varied Origins

The exact lineage of the Brandywine tomato is shrouded in a captivating mystique, contributing significantly to its heirloom allure. While its precise origins remain a subject of friendly debate among tomato enthusiasts, the consensus places its emergence in the late 19th century, with strong ties to Pennsylvania and the tradition of Mennonite farming communities. The name itself is believed by many to be a reference to the Brandywine Creek region, which flows through southeastern Pennsylvania and northern Delaware, suggesting a localized development.

One of the most frequently cited theories attributes the initial popularization of what is often considered the “original” Brandywine Pink to a woman named Dorothy Sudduth from Ohio. Her family reportedly cultivated this particular strain for generations, passing it down through an unbroken chain of seed saving. This specific variety, often referred to as ‘Brandywine (Sudduth’s Strain),’ is highly prized for its exceptional flavor and is characterized by its distinctive “potato leaf” foliage – broad, smooth leaves that lack the typical indentations of standard tomato leaves. This unique leaf shape is a key identifier for many classic Brandywine types.

However, the Brandywine narrative is not singular. Over time, various strains and mutations have emerged, leading to a diverse family of tomatoes all bearing the Brandywine name but possessing subtle differences. For instance, the ‘Brandywine OTV’ (Ohio Yellow Tomato) is another popular variety, though its connection to the Sudduth’s strain or the original Pennsylvania Brandywine is less direct. It’s thought to be an unrelated heirloom from Ohio that was simply given the Brandywine moniker due to its similar large size and high quality. It typically exhibits “regular leaf” foliage, distinguishing it visually from the Sudduth’s strain.

The widespread appeal of Brandywine truly took off in the latter half of the 20th century, largely due to the efforts of seed savers and heirloom preservationists who recognized its unparalleled culinary value. As commercial agriculture increasingly focused on varieties suitable for mass production and long-distance shipping, the exquisite flavor of traditional heirlooms like Brandywine became a precious commodity, sought after by those yearning for the taste of a “real” tomato. Its storied past, coupled with its undeniable flavor, has solidified Brandywine’s place as a cornerstone of the heirloom tomato movement.

Distinguishing Characteristics and Popular Brandywine Varieties

The term “Brandywine tomato” is somewhat of a broad umbrella, encompassing several distinct varieties that share a common reputation for exceptional flavor and large fruit size. Understanding these distinctions is crucial for gardeners wishing to select the perfect Brandywine for their palate and growing conditions. While all Brandywines are indeterminate (meaning they continue to grow and produce fruit throughout the season until frost), their foliage, fruit color, and subtle flavor notes can vary.

Brandywine Pink (Sudduth’s Strain)

This is often considered the quintessential Brandywine, the benchmark against which others are judged.

Foliage: Distinctive potato leaf, characterized by broad, smooth, un-serrated leaves. This is a primary identifier.
Fruit: Large beefsteak type, often weighing 12-24 ounces, with some fruits exceeding a pound. The skin is a deep, rosy pink.
Flavor: Renowned for its complex, rich, sweet, and tangy flavor, often described as “old-fashioned tomato taste.” The texture is creamy and meaty with few seeds.
Yield: Generally moderate to lower yields compared to some other tomatoes, but the quality of individual fruits is outstanding.
Maturity: A long-season variety, typically maturing in 80-100 days from transplant.

Brandywine Red

While sharing the Brandywine name, this variety typically possesses different characteristics from its pink counterpart.

Foliage: Usually regular leaf, with the classic serrated edges common to most tomato plants.
Fruit: Also a large beefsteak, often slightly smaller than the Pink, with a vibrant, deep red color.
Flavor: Offers a robust, full-bodied red tomato flavor, often described as slightly more acidic or less creamy than the Pink, but still excellent.
Yield: Tends to be more productive than Brandywine Pink, making it a good choice for those seeking higher yields without sacrificing too much on flavor.
Maturity: Similar long season, around 80-90 days from transplant.

Brandywine Yellow (OTV – Ohio Yellow Tomato)

This distinct heirloom is highly valued for its unique color and flavor profile.

Foliage: Predominantly regular leaf, though potato leaf versions may exist from different selections.
Fruit: Large, globular to slightly flattened beefsteaks, ripening to a beautiful golden yellow.
Flavor: Sweet, fruity, and less acidic than the pink or red varieties, with a smooth, meaty texture. It’s often praised for its mildness and excellent slicer quality.
Yield: Good productivity for an heirloom, often more consistent than the Pink Brandywine.
Maturity: Generally matures slightly earlier than the Pink, in the 78-85 day range.

Other Noteworthy Mentions

While the Pink, Red, and Yellow are the most common, other variations exist, sometimes arising from natural crosses or selections. ‘Brandywine Black’ is an example, often showcasing a darker, rich flavor profile, but typically is a newer, distinct selection rather than an ancient Brandywine strain. The key takeaway is that when seeking an authentic Brandywine experience, especially the famed “old-fashioned” flavor, opting for ‘Brandywine Pink (Sudduth’s Strain)’ with its characteristic potato leaf foliage is often recommended.

Cultivation Guide: Planting Brandywine Seeds for Success

Growing Brandywine tomatoes from seed is a deeply rewarding endeavor, offering control over the plant’s initial health and ensuring access to specific, true-to-type varieties. Due to their long growing season, starting Brandywine seeds indoors is almost always necessary for most temperate climates.

Timing Your Seed Starting

Begin your Brandywine seeds indoors approximately 6-8 weeks before your region’s average last frost date. This critical window allows the seedlings to develop into robust young plants ready for transplanting once outdoor conditions are favorable. Planting too early can result in leggy, overgrown seedlings that struggle after transplant, while planting too late may mean fruits don’t fully ripen before the first autumn frost.

Materials and Method for Seed Starting

Seed Starting Mix: Use a high-quality, sterile, fine-textured seed starting mix. Avoid garden soil, which can harbor pathogens and compact too easily, hindering germination.
Containers: Seed trays, individual cells, or small pots (2-4 inches) with drainage holes are ideal. Ensure they are clean.
Planting Depth: Sow seeds about 1/4 inch deep. Gently cover with seed starting mix.
Watering: Moisten the soil thoroughly before planting, then keep it consistently damp but not waterlogged. A spray bottle or bottom watering can help prevent disturbing the seeds.
Temperature: Maintain a consistent soil temperature of 75-85°F (24-29°C) for optimal germination. Heating mats placed under trays can significantly improve germination rates and speed.
Light: Once seeds germinate and sprouts emerge, provide ample light immediately. Grow lights are essential for preventing leggy growth. Position lights 2-4 inches above the seedlings, adjusting as they grow, and run them for 14-16 hours daily.
Air Circulation: A small fan can help strengthen stems and reduce the risk of damping-off disease.

Hardening Off Your Seedlings

Before transplanting your Brandywine seedlings outdoors, they must be “hardened off.” This gradual process acclimates them to outdoor conditions (sunlight, wind, temperature fluctuations) and prevents transplant shock. Over a period of 7-10 days:

Start by placing seedlings outdoors in a sheltered, shady spot for a few hours.
Each day, gradually increase their exposure to direct sunlight and outdoor elements.
Bring them indoors if nighttime temperatures drop below 50°F (10°C).
Reduce watering slightly but don’t let them dry out completely.

Site Selection and Soil Preparation

Brandywine tomatoes are sun-loving plants that thrive in rich, well-drained soil.

Sunlight: Choose a location that receives at least 6-8 hours of direct sunlight per day, ideally more.
Soil pH: Aim for a soil pH between 6.0 and 6.8. A soil test can provide valuable insights.
Soil Amendment: Amend your garden beds generously with aged compost or other organic matter. This improves soil structure, drainage, and nutrient content, providing an ideal environment for Brandywine’s extensive root system.
Crop Rotation: Avoid planting tomatoes in the same spot where other nightshades (tomatoes, peppers, eggplants, potatoes) have grown in the past 2-3 years to minimize disease transmission.

Transplanting Outdoors

Transplant your hardened-off Brandywine seedlings after all danger of frost has passed and soil temperatures have warmed sufficiently (ideally above 60°F or 15°C).

Spacing: Brandywine plants grow very large and require ample space. Plant them 3-4 feet apart in rows, with rows spaced 4-5 feet apart. Good air circulation is vital for disease prevention.
Deep Planting: Tomatoes are unique in their ability to grow roots from their stems. Bury a significant portion of the stem (up to the first set of true leaves) when transplanting. This encourages a stronger, more extensive root system.
Initial Watering: Water thoroughly immediately after transplanting to settle the soil around the roots.

Ongoing Care and Maintenance for Thriving Brandywine Plants

Cultivating successful Brandywine plants requires consistent attention to their needs throughout the growing season. Their large size, heavy fruit load, and extended ripening period demand specific care strategies.

Consistent Watering Regimen

Watering is perhaps the most critical factor in successful Brandywine cultivation. Inconsistent watering is a primary cause of common tomato problems like blossom end rot and fruit cracking.

Deep and Infrequent: Aim for deep watering sessions rather than shallow, frequent ones. This encourages roots to grow deeper, making the plant more resilient.
Timing: Water early in the morning to allow foliage to dry before evening, reducing the risk of fungal diseases.
Amount: Provide about 1-1.5 inches of water per week, either from rain or irrigation. During hot, dry spells or when fruits are developing, they may require more.
Method: Drip irrigation, soaker hoses, or careful hand watering at the base of the plant are preferable to overhead watering, which can spread diseases.

Strategic Fertilization

Brandywine plants are heavy feeders, but the type and timing of fertilizer are important.

Initial Growth: After transplanting, a balanced fertilizer (e.g., 5-10-5 or 10-10-10) can support initial growth.
Flowering and Fruiting: Once flowering begins, switch to a fertilizer lower in nitrogen and higher in phosphorus and potassium (e.g., 5-10-10 or specific tomato fertilizers). Excess nitrogen promotes leafy growth at the expense of fruit production.
Organic Options: Compost tea, fish emulsion, or balanced organic granular fertilizers can provide slow-release nutrients.
Application: Follow package directions and avoid over-fertilizing, which can burn roots or lead to imbalanced growth.

Essential Support Systems

Given their indeterminate growth habit and the substantial weight of their fruits, Brandywine plants absolutely require robust support from an early stage. Failure to provide adequate support will result in plants sprawling on the ground, making them more susceptible to pests, diseases, and sunscald.

Staking: Heavy-duty stakes (e.g., 2×2 wooden stakes, rebar, or sturdy metal posts 6-8 feet tall) driven deep into the ground near the plant are effective. Tie the main stem to the stake loosely with soft ties as the plant grows.
Caging: Large, sturdy tomato cages designed for indeterminate varieties are also an option. Avoid flimsy cages that will collapse under the weight of Brandywine. Custom-built cages from concrete reinforcing wire (C-mesh) are often preferred.
Trellising: For ambitious growers, a robust trellis system can provide excellent support and air circulation.

Pruning and Pest/Disease Management

While the debate over pruning heirloom tomatoes continues, some practices can benefit Brandywine.

Sucker Removal: Removing some suckers (shoots that grow in the crotch between the main stem and a leaf branch) can redirect energy into fruit production and improve air circulation. However, excessive pruning can reduce yield. A common approach is to allow 2-4 main stems to develop.
Lower Leaf Removal: Once the plant is established and fruits begin to set, removing the lower leaves that touch the soil can help prevent soil-borne diseases from splashing onto the foliage.
Mulching: Apply a 2-4 inch layer of organic mulch (straw, shredded leaves, grass clippings) around the base of plants. Mulch conserves soil moisture, suppresses weeds, regulates soil temperature, and provides a barrier against soil-borne pathogens.
Pest Monitoring: Regularly inspect plants for common pests like tomato hornworms (handpick and destroy), aphids (spray with insecticidal soap), and spider mites.
Disease Prevention: Good air circulation, consistent watering, and proper spacing are the best defenses against fungal diseases like early blight and late blight, to which heirlooms can be more susceptible. Remove any diseased foliage promptly.

Harvesting and Savoring Your Brandywine Tomatoes

The culmination of your efforts with Brandywine tomatoes is the long-awaited harvest. Knowing when to pick, how to store, and the best ways to enjoy these magnificent fruits ensures you fully appreciate their legendary flavor.

When to Harvest

Brandywine tomatoes are typically ready for harvest 80-100 days after transplanting, depending on the specific variety and growing conditions. Unlike some commercial varieties, Brandywines signal their ripeness subtly.

Color: The most obvious indicator is color. Pink Brandywines will develop a deep, rosy pink hue; Reds will be a rich, uniform red; and Yellows will turn a golden yellow. The shoulders of the fruit may retain a greenish tint, which is normal for many heirlooms.
Feel: Gently cup the tomato in your hand and apply slight pressure. A ripe Brandywine will feel firm but yield slightly to a gentle squeeze. Avoid rock-hard tomatoes (underripe) or mushy ones (overripe).
Stem: A ripe tomato should easily detach from the vine with a slight twist or gentle tug. If it resists, it likely needs a few more days. For best results and to avoid damaging the plant, use clean pruners or scissors to snip the stem just above the calyx (the leafy cap).

Harvesting often begins in mid-to-late summer and can continue until the first hard frost. Regular harvesting encourages the plant to produce more fruit.

Optimal Storage Practices

The flavor and texture of Brandywine tomatoes are best preserved when stored correctly.

Room Temperature: Never refrigerate ripe tomatoes. Cold temperatures destroy the volatile compounds responsible for their complex flavor and can turn the texture mealy. Store ripe tomatoes at room temperature, ideally between 55-70°F (13-21°C), away from direct sunlight.
Stem Side Down: Placing tomatoes stem side down can help prevent moisture loss and inhibit the entry of air and bacteria.
Ripening Unripe Tomatoes: If you pick slightly unripe tomatoes before a frost, they can be ripened indoors. Place them in a paper bag with a banana or apple (which release ethylene gas) and store at room temperature. Check daily.
Consumption Window: Ripe Brandywines are best consumed within a few days of harvest for peak flavor.

The Culinary Delights of Brandywine

Brandywine tomatoes are prized for their versatility in the kitchen, but their extraordinary flavor shines brightest when enjoyed fresh and minimally processed.

Slicing: Their large, meaty, and relatively seed-free interiors make them perfect for thick slices on sandwiches, burgers, or as a stand-alone side dish with a sprinkle of sea salt and a drizzle of good olive oil.
Salads: Cube them into fresh garden salads or make a classic Caprese salad with mozzarella, basil, and balsamic glaze.
Bruschetta: Diced Brandywine tomatoes, combined with garlic, basil, and olive oil, make an exquisite topping for toasted bread.
Fresh Sauces: While not typically considered a canning tomato due to their lower acidity and high water content, their flavor is incredible in fresh, uncooked sauces or quick-cooked pasta sauces where the fresh taste can dominate.

The essence of enjoying a Brandywine is to let its natural flavors be the star of the dish.

Addressing Common Challenges and Troubleshooting Brandywine Issues

While the reward of a perfectly ripe Brandywine is immense, growing these heirlooms isn’t without its challenges. Understanding common issues and how to address them can save your crop and your sanity.

Lower Yields Compared to Hybrids

One of the most frequent observations about Brandywine is its tendency to produce fewer fruits per plant than modern hybrid varieties. This is a characteristic of many large-fruited heirloom tomatoes.

Explanation: The plant invests significant energy into growing fewer, but much larger, fruits. Hybrids are often bred for higher fruit set and uniform size.
Solution: Accept this as part of the heirloom experience. If high yield is a priority, plant more Brandywine plants or supplement with other, more prolific varieties. Focus on quality over quantity.

Cracking and Splitting Fruit

Brandywine tomatoes are prone to concentric (around the stem) or radial (from the stem end downwards) cracking, especially as they ripen.

Cause: This primarily occurs due to inconsistent watering, particularly when a dry spell is followed by a sudden influx of moisture (rain or irrigation). The fruit skin hardens during dry periods, and a sudden surge of water causes rapid internal expansion, leading to splits.
Solution: Maintain consistent soil moisture through regular, deep watering. Mulching heavily around the plants helps regulate soil moisture. Harvest fruits promptly when ripe, especially before anticipated heavy rains.

Blossom End Rot (BER)

BER manifests as a dark, sunken, leathery spot on the bottom (blossom end) of the fruit.

Cause: BER is not typically caused by a lack of calcium in the soil itself, but rather by the plant’s inability to transport sufficient calcium to the developing fruit. This is most often due to inconsistent watering (leading to fluctuations in calcium uptake), rapid growth, or damaged roots.
Solution: The most effective prevention is consistent, deep watering. Ensure soil pH is correct, as extreme pH can hinder nutrient uptake. Amend soil with organic matter to improve water retention. Avoid over-fertilizing with high-nitrogen fertilizers early in the season.

Late Ripening and Green Shoulders

Brandywine tomatoes are long-season varieties, meaning they take a longer time to mature. They also often exhibit “green shoulders,” where the area around the stem remains greenish even when the rest of the fruit is ripe.

Explanation: This is a normal genetic trait for many heirlooms, including Brandywine. It does not necessarily indicate unripeness and is often due to chlorophyll remaining in the skin even after ripening.
Solution: Be patient! Harvest based on overall color and feel. The green shoulders will soften and often sweeten up after a day or two indoors at room temperature. Ensure plants receive full sun throughout the growing season.

Disease Susceptibility

Heirloom varieties like Brandywine generally lack the modern disease resistance packages bred into many hybrid tomatoes. They can be more susceptible to common tomato diseases.

Cause: Lack of specific genetic resistance to common fungal (e.g., early blight, late blight) and bacterial diseases.
Solution: Implement good cultural practices: ensure proper spacing for air circulation, water at the base of the plant, rotate crops, and promptly remove any diseased plant material. Choose disease-resistant companions if applicable. In humid climates, organic fungicides (e.g., copper or sulfur-based) may be considered as a preventative measure or at the first sign of disease, following label instructions carefully.

The Irresistible Allure: Why Choose Brandywine?

Despite the challenges and specific care requirements, Brandywine tomatoes continue to captivate gardeners year after year. Their enduring popularity is a testament to unique qualities that transcend mere horticultural performance.

Unparalleled Flavor Profile

At the core of Brandywine’s appeal is its legendary flavor. It’s often described as the epitome of “old-fashioned tomato taste” – a complex symphony of sweet, tangy, and savory notes, perfectly balanced. The texture is creamy, meaty, and juicy, making it ideal for slicing. This flavor stands in stark contrast to the often bland, uniform taste of commercially grown tomatoes, offering a profound culinary experience that is hard to match. For many, one bite of a perfectly ripened Brandywine is enough to convert them into lifelong devotees.

A Connection to Agricultural Heritage

Growing Brandywine tomatoes is more than just cultivating a plant; it’s participating in a living history. Its mysterious origins and generations of careful seed saving connect the gardener to the past, preserving genetic diversity and traditional foodways. It’s a tangible link to a time when flavor, rather than shelf-life or uniform appearance, was the ultimate measure of a tomato’s worth.

The Satisfaction of a Rewarding Challenge

Brandywine is not the easiest tomato to grow, and its demanding nature can be part of its appeal. Successfully bringing a crop of these magnificent fruits to harvest provides a deep sense of accomplishment. It encourages gardeners to hone their skills, observe their plants closely, and understand the nuances of their local growing environment. The effort invested is generously repaid with a superior culinary reward.

Championing Biodiversity

By choosing to grow an heirloom like Brandywine, gardeners actively contribute to the preservation of agricultural biodiversity. Each seed saved and shared helps to ensure that these unique varieties, with their irreplaceable genetic traits and flavors, continue to exist for future generations. In an era dominated by a handful of commercial varieties, supporting heirlooms is an act of environmental stewardship.

In essence, choosing Brandywine is choosing a narrative – a narrative of taste, tradition, perseverance, and a deep appreciation for the natural world. It’s an invitation to experience tomato growing at its most authentic and rewarding.

Preserving the Lineage: Saving Brandywine Seeds for Future Generations

One of the most beautiful aspects of growing heirloom tomatoes like Brandywine is the ability to save their seeds, ensuring that their unique characteristics and unparalleled flavor can be enjoyed for years to come and passed on to future generations of gardeners. Brandywine varieties are open-pollinated, meaning their seeds will reliably produce plants true to the parent type, unlike hybrid varieties whose seeds will revert to their parentage or produce sterile offspring.

Why Save Brandywine Seeds?

Preservation: You become a part of the long chain of gardeners who have kept this heirloom alive for over a century.
Cost Savings: No need to buy new seeds every year.
Adaptation: Over time, seeds saved from your garden may subtly adapt to your specific microclimate, potentially leading to stronger, more productive plants in your particular environment.
Self-Sufficiency: Fosters a deeper connection to your food and gardening cycle.

The Fermentation Method: Best Practice for Tomato Seeds

The fermentation method is highly recommended for saving tomato seeds as it helps remove germination inhibitors, kills seed-borne diseases, and cleans the seeds effectively.

Select the Best Fruit: Choose ripe, healthy, disease-free fruits from your most vigorous, productive Brandywine plants. Avoid fruits from plants that showed signs of disease or stress. The fruit should be fully mature – beyond eating ripeness is often ideal for seed saving.
Extract the Seeds: Cut the chosen tomato in half horizontally. Using a spoon, scoop out the seeds and the surrounding gel-like pulp into a clean jar or container. Label the jar immediately with the tomato variety and date.
Add Water: Add a small amount of water to the jar, just enough to cover the seeds and pulp.
Ferment: Cover the jar loosely (a lid or cheesecloth will do; don’t seal it tightly as gases will be produced) and place it in a warm location, out of direct sunlight. Over the next 2-5 days, a layer of mold may form on top, and the mixture will begin to ferment, smelling slightly yeasty. This process breaks down the gelatinous sac around each seed, which contains germination inhibitors. Stir the mixture once or twice a day.
Monitor for Sinking Seeds: Healthy, viable seeds will eventually sink to the bottom of the jar as the pulp and unviable seeds float to the top. The fermentation process is complete when most viable seeds have sunk, and a clear distinction can be seen between the floating mold/pulp and the settled seeds. Do not ferment for too long (e.g., more than a week), as seeds can begin to germinate in the jar.
Rinse and Clean: Once fermentation is complete, carefully pour off the floating pulp, mold, and unviable seeds. Add fresh water to the jar, stir, and let the good seeds settle again. Repeat this rinsing process several times until the water runs clear and only clean seeds remain at the bottom. A fine-mesh strainer can be helpful for this step.
Dry the Seeds: Spread the clean seeds in a single layer on a non-stick surface to dry. Options include a ceramic plate, glass, parchment paper, or coffee filters. Avoid paper towels as seeds can stick. Place the drying seeds in a warm, dry area with good air circulation, away from direct sunlight.
Ensure Complete Drying: Allow the seeds to dry thoroughly for 1-3 weeks. They should be brittle and easily snap in half, not bend. Any residual moisture can lead to mold and spoilage during storage.
Store Properly: Once completely dry, store the seeds in airtight containers (e.g., small glass jars, Ziploc bags, or seed envelopes) in a cool, dark, and dry location. A cupboard or closet is generally suitable. For longer viability, seeds can be stored in the refrigerator or freezer. Always label containers clearly with the variety and the date saved.

Preventing Cross-Pollination

While tomatoes are primarily self-pollinating (meaning pollen from a flower typically fertilizes that same flower), cross-pollination can occur, especially with the help of insects. To ensure the purity of your Brandywine seeds, particularly if you are growing multiple open-pollinated tomato varieties, consider these practices:

Isolation Distance: For hobby gardeners, planting different varieties at least 10-20 feet apart is often sufficient to minimize accidental cross-pollination. Commercial seed savers may use much greater distances (up to 50 feet or more).
Caging/Bagging Flowers: For absolute purity, individual flower clusters can be enclosed in small organza bags or covered before they open, and then hand-pollinated. This is typically reserved for very specific seed-saving projects.
Accept Slight Variation: For home gardeners, a tiny percentage of cross-pollination is often acceptable. The majority of saved seeds will still produce true-to-type Brandywine plants.

By following these steps, you not only ensure a supply of your favorite Brandywine seeds for the next growing season but also contribute to the ongoing legacy of this extraordinary heirloom tomato.