How do You Earth up Potatoes? - Plant Care Guide

To earth up potatoes, you simply draw soil or other organic material around the potato plants as they grow. This process, also known as hilling, involves mounding soil up around the stems, covering part of the foliage. The goal is to protect developing tubers from sunlight and encourage the formation of more potatoes.

Why Should You Earth Up Potatoes?

Earthing up potatoes is a time-honored gardening practice with several key benefits that contribute to a healthier plant and a more abundant harvest. It's a simple technique that plays a big role in successful potato growing. Understanding these reasons will highlight why it's such an important step for any potato grower.

How Does Hilling Protect Potatoes from Sunlight?

One of the primary reasons to earth up potatoes is to shield the developing tubers from direct sunlight. Potato tubers, which are modified stems, form underground and are meant to stay in the dark.

Here's why sunlight is a problem for potatoes:

• Solanine Production: Exposure to sunlight triggers the production of solanine, a natural glycoalkaloid that gives potatoes a green color and a bitter taste. While solanine is present in all potatoes, high concentrations make them inedible and potentially toxic.
• Green Skin: You'll notice green spots or patches on potatoes that have been exposed to light. This greening is a visual indicator of increased solanine levels.
• Reduced Quality: Even if not entirely green, light exposure can negatively impact the flavor and quality of your harvest. Potatoes meant for storage will also have a shorter shelf life if they've been exposed to light.

By mounding soil around the growing stems, you create a deeper layer of darkness that developing potatoes can form within. This keeps them safely tucked away from the sun's rays, ensuring they remain unblemished, palatable, and safe to eat. Hilling acts as a natural sunblock for your spuds.

Does Earthing Up Increase Potato Yields?

Yes, earthing up can significantly contribute to increasing potato yields. Potatoes form on specialized underground stems called stolons. When you cover a portion of the main stem with soil, it encourages the plant to produce more stolons from the covered nodes.

Here's how hilling boosts your harvest:

• More Stolons: Each node (the point on the stem where a leaf or branch emerges) that is covered by soil has the potential to produce new stolons. More stolons mean more places for potatoes to form.
• Additional Tuber Development: By providing a deeper, darker, and looser soil environment, hilling creates ideal conditions for these new stolons to swell and develop into tubers. Essentially, you're giving the plant more "room" to grow potatoes vertically along the stem.
• Healthier Plants: A well-hilled plant often has a more stable base, making it less susceptible to wind damage. This stability allows the plant to put more energy into tuber production rather than struggling against external forces.

Gardeners often find that hilled potato plants produce a greater number of tubers per plant compared to those left unhilled. It's an efficient way to maximize the potential of each potato plant in your garden bed or grow bag.

What Other Benefits Does Hilling Provide for Potatoes?

Beyond protecting from light and increasing yield, earthing up potatoes offers several other advantages that promote overall plant health and make gardening easier. These benefits contribute to a more resilient and productive potato patch.

Other benefits of hilling include:

• Weed Suppression: The mounds of soil help to smother young weeds around the base of the potato plants. This reduces competition for water and nutrients, allowing your potatoes to thrive without interference. Fewer weeds also mean less time spent on manual weeding.
• Moisture Retention: The elevated soil mounds can help to shade the soil surface, reducing evaporation and improving moisture retention around the plant's root zone. This is especially helpful during dry spells, reducing the need for frequent watering.
• Temperature Regulation: The extra layer of soil provides a buffer against extreme temperature fluctuations. It helps to keep the soil cooler during hot days and warmer during cool nights, providing a more consistent and favorable environment for tuber development.
• Improved Drainage: For gardens with heavier clay soils, hilling can subtly improve localized drainage around the potato roots. Potatoes prefer well-drained soil, and raising them slightly can help prevent waterlogging.
• Anchoring Plants: As potato plants grow taller, they can become top-heavy. The soil mounds provide additional support, anchoring the plants and making them less prone to toppling over in strong winds. This protects the stems and prevents potential damage.

When is the Best Time to Earth Up Potatoes?

Timing is crucial when it comes to earthing up potatoes. The process isn't a one-time event but rather a series of actions performed as the potato plants grow. Knowing when to start and when to continue hilling ensures maximum effectiveness.

When Should You Start Earthing Up?

You should start earthing up potatoes when the plant's foliage reaches a height of about 6-8 inches (15-20 cm) tall. This is typically a few weeks after the plants have emerged from the soil. Don't wait until the plants are too tall, as it can be harder to manage the soil without damaging the tender shoots.

Initial hilling involves:

1. Observing Growth: Once you see robust green shoots with several leaves emerging, it's time to prepare for the first hilling.
2. Gathering Material: Have your chosen material ready, whether it's loose garden soil, compost, or straw.
3. Gentle Mounding: Carefully draw the material around the base of the plants, covering the lower 4-6 inches of foliage. You want to leave only the top few inches of green leaves exposed.

This initial hilling creates the foundation for subsequent mounds and immediately begins the process of encouraging more tubers.

How Often Do You Need to Hill Potatoes?

Hilling potatoes is a continuous process that you'll repeat several times throughout the growing season, typically until the plants begin to flower. As the potato plants grow taller, you'll continue to add more material.

Repeat the hilling process:

• Every 2-3 Weeks: As a general guideline, re-hill your potatoes every 2-3 weeks, or whenever the green foliage reaches another 6-8 inches (15-20 cm) above the top of your existing mound.
• Keep Covering: Each time, draw more soil or material around the stems, again leaving only the top few inches of growth exposed.
• Stop at Flowering: Most gardeners stop hilling when the potato plants begin to flower. At this point, the plant's energy shifts from vegetative growth to tuber development, and further hilling becomes less effective for increasing yield. However, you might still add a final layer if any tubers are exposed to light.
• Maximum Height: The final mound height can vary, but generally aim for a mound that is at least 12-18 inches (30-45 cm) tall from the original planting depth.

Consistent hilling ensures continuous protection for developing tubers and optimizes the plant's ability to produce a bountiful crop.

What Materials Can You Use for Earthing Up?

While garden soil is the most traditional material, you have several options for earthing up potatoes. The best choice often depends on your soil type, available resources, and specific gardening goals. Each material offers distinct advantages.

Can You Use Garden Soil for Hilling?

Yes, garden soil is the most common and traditional material used for earthing up potatoes. It's readily available in most gardens and provides good structure.

Considerations for using garden soil:

• Availability: It's right there in your garden, so there's no need to purchase extra materials.
• Nutrient Content: If your garden soil is rich in organic matter, it will naturally provide some nutrients to the developing tubers.
• Workability: Ensure your garden soil is loose and friable, not heavy clay that compacts easily. Heavy, compacted soil can hinder tuber expansion. If your soil is very heavy, you might want to amend it with compost before hilling or use a different material.
• Tool Friendly: A garden hoe or a hilling tool works very well with garden soil.

When using garden soil, simply draw it up from between the rows or from nearby pathways. If your soil is poor, consider enriching it with a layer of compost first.

What About Using Compost for Earthing Up?

Compost is an excellent choice for earthing up potatoes, offering numerous benefits beyond just physical coverage. It enriches the soil and promotes healthier growth.

Benefits of using compost:

• Nutrient Rich: Compost is full of beneficial microbes and essential nutrients, which feed your potato plants as it breaks down. This can lead to a more vigorous plant and larger, healthier tubers.
• Improved Soil Structure: It lightens heavy soils and adds body to sandy soils, improving drainage and aeration, which potatoes love.
• Moisture Retention: Compost has excellent water-holding capacity, helping to keep the soil consistently moist without being waterlogged.
• Weed Suppression: Like soil, a good layer of compost will help suppress weeds.

If you have access to plenty of homemade compost, it's arguably the best material for hilling your potatoes. It's a win-win for both plant health and soil improvement.

Can You Earth Up Potatoes with Straw or Hay?

Yes, using straw or hay is an increasingly popular and highly effective method for earthing up potatoes, often referred to as the "straw method" or "no-dig method." This approach has several distinct advantages.

Advantages of straw or hay hilling:

• Ease of Harvest: This is perhaps the biggest benefit. At harvest time, instead of digging through compacted soil, you simply pull back the straw to reveal your clean potatoes, often just sitting on the soil surface. This makes harvesting incredibly easy and reduces damage to tubers.
• Excellent Weed Suppression: A thick layer of straw is very effective at blocking sunlight, preventing weed seeds from germinating and growing.
• Moisture Regulation: Straw acts as a mulch, significantly reducing water evaporation from the soil. It also helps regulate soil temperature, keeping it cooler in summer and warmer in cooler periods.
• Improved Soil Health: As the straw breaks down, it adds organic matter to your garden soil, improving its structure and fertility over time.
• Less Soil Compaction: Since you're not mounding heavy soil, there's less risk of compacting the earth around the developing tubers, allowing them to expand more freely.

When using straw or hay, apply it in thick layers, aiming for 6-12 inches (15-30 cm) each time you hill. Be sure to use actual straw (dried stalks of grain) rather than hay (dried grasses with seeds), as hay can introduce unwanted weed seeds into your garden. If you're short on straw, even wood chips or dried leaves can be used in a pinch, though they may break down slower.

How to Earth Up Potatoes Step-by-Step

The process of earthing up potatoes is straightforward, but consistency and care are important. Whether you're a seasoned gardener or just starting, these steps will guide you to a successful hilling technique.

Step 1: Prepare Your Tools and Materials

Before you begin earthing up, ensure you have the right tools and your chosen material ready. This makes the process efficient and prevents damage to your plants.

• Choose Your Material: Decide whether you'll use garden soil, compost, straw, or a mix. Have enough on hand for the current hilling.
• Select Your Tools:
  • A garden hoe is excellent for pulling soil or compost around the plants.
  • A spade or shovel might be needed to gather material if you're not pulling from between rows.
  • For working with straw, your hands or a pitchfork work well.
  • A good pair of gardening gloves will protect your hands.

Having everything organized will save you time and effort as you work through your potato rows.

Step 2: Identify When to Start Hilling

As mentioned earlier, timing is key. Observe your potato plants closely for the first signs that it's time to begin the hilling process.

• Plant Height: Wait until your potato plants are approximately 6-8 inches (15-20 cm) tall above the ground. At this stage, they are robust enough to handle the added material.
• Foliage Development: Ensure there's enough green foliage to leave a few inches exposed after hilling. This ensures the plant can still photosynthesize effectively.

Don't rush the first hilling, but also don't wait too long. An ideal window provides enough growth without making the task cumbersome.

Step 3: Gently Mound Material Around the Stems

This is the core of earthing up. The goal is to carefully draw your chosen material around the base of the plants without burying the entire plant.

• Using Soil/Compost:

  • Stand between your potato rows.
  • Using your hoe, gently draw soil or compost from the aisles or between the plants towards the base of the potato stem.
  • Form a mound around the stem, covering the lower 4-6 inches (10-15 cm) of the plant.
  • Ensure that only the top 2-3 inches (5-7 cm) of green foliage remain visible above the mound.
  • Be careful not to damage the tender stems or leaves.

• Using Straw/Hay:

  • Grab handfuls of straw or hay.
  • Carefully place it around the base of the plant, building a thick layer.
  • Again, cover most of the stem, leaving only a few inches of green leaves exposed at the top.
  • Aim for an initial layer of about 6 inches (15 cm) of straw.

The mound should be gently sloped, like a small hill, to allow for water run-off and prevent waterlogging around the stem.

Step 4: Repeat the Hilling Process as Plants Grow

Earthing up isn't a one-time job. You'll need to revisit your potato patch as the plants continue their vigorous growth.

• Monitor Growth: Keep an eye on your potato plants. Once they grow another 6-8 inches (15-20 cm) above the last mound, it's time for the next hilling. This usually means repeating the process every 2-3 weeks.
• Add More Material: Repeat Step 3, adding more soil, compost, or straw to the existing mound.
• Continue Until Flowering: Keep hilling until the potato plants begin to flower. This typically signals that the plant is shifting its energy towards forming tubers, and further hilling will have diminishing returns for yield. However, if you see any signs of greening tubers poking through the soil, add another layer for protection.
• Final Mound Height: Aim for a final mound that is 12-18 inches (30-45 cm) tall from the original planting level, creating a substantial "hill" for your potatoes.

Consistent hilling throughout the growing season ensures that your potatoes have ample dark space to develop and are protected from the sun.

What Are the Different Methods for Earthing Up Potatoes?

Beyond the material used, there are a couple of common methods for earthing up potatoes, especially depending on how you've planted them. Each method achieves the same goal but is adapted to different planting configurations.

How Do You Hill Potatoes Planted in Rows?

Earthing up potatoes planted in traditional rows is the most common method and is usually done using a hoe or hilling attachment on a garden tiller. This method allows for efficient work across a larger area.

Steps for hilling in rows:

1. Plant in Furrows: Start by planting your seed potatoes in shallow furrows, about 4-6 inches (10-15 cm) deep. This gives you a natural trench to work with.
2. First Hilling: Once plants are 6-8 inches tall, use a garden hoe to gently pull soil from the sides of the furrow and between the plants, mounding it up around the base of the stems. You'll create a small ridge down the row.
3. Subsequent Hillings: As the plants grow taller, continue to draw more soil from the aisles between the rows, increasing the size and height of the ridge. You're effectively building up the soil around the potato plants, creating a deep mound.
4. Creating Trenches: As you pull soil from the aisles, you'll naturally create new, shallow trenches between your potato rows. These can sometimes be useful for directing irrigation water.

This row method is very effective for larger potato patches and is the classic way gardeners have hilled potatoes for centuries.

How Do You Earth Up Potatoes in Containers or Grow Bags?

Earthing up potatoes in containers or grow bags requires a slightly different approach than in-ground planting, but the principle remains the same. This method is popular for urban gardeners or those with limited space.

Steps for hilling in containers:

1. Start Shallow: When planting in a potato grow bag or large container, start by adding only about 6-8 inches (15-20 cm) of good quality potting mix or compost at the bottom. Plant your seed potatoes on this layer.
2. First Hilling: Once the potato plants have grown to about 6-8 inches (15-20 cm) tall, add another 4-6 inches (10-15 cm) of potting mix or compost around the stems, again leaving only the top few inches of foliage exposed.
3. Continue Adding Material: As the plants grow taller, continue to add layers of potting mix or compost. You'll typically do this 2-3 times until the container or bag is almost full.
4. Fill the Container: Keep adding material until the container is filled to within a few inches of the rim. This provides ample space for tubers to develop throughout the depth of the container.

Using grow bags makes this process especially easy, as you can simply unroll the sides of the bag as you add more growing medium. For rigid containers, just keep adding material until it reaches the desired height.

Are There Any Downsides or Mistakes to Avoid When Earthing Up?

While earthing up potatoes is generally beneficial, there are a few potential downsides and common mistakes that gardeners should be aware of. Avoiding these pitfalls will ensure your hilling efforts are successful and don't inadvertently harm your crop.

What are Common Mistakes to Avoid When Hilling?

Knowing what not to do is just as important as knowing what to do when earthing up potatoes. These common errors can hinder growth or reduce your harvest.

Common mistakes to avoid:

• Hilling Too Early or Too Late: Hilling when plants are too small can bury and smother them. Waiting too long means tubers might be exposed to light before you get a chance to cover them, or the plants might be too large and delicate to handle easily.
• Burying All Foliage: Always leave at least a few inches of green leaves exposed at the top of the plant. The leaves are crucial for photosynthesis, which is how the plant produces the energy it needs to grow and form tubers. Burying all the leaves will stunt growth.
• Using Compacted or Heavy Soil: If you're using garden soil, ensure it's loose and friable. Heavy, clay-rich soil can become compacted around the developing tubers, restricting their growth and potentially leading to misshapen potatoes. Amend heavy soil with compost or use lighter materials like straw.
• Damaging Stems: Be gentle when drawing soil around the plants. Potato stems can be brittle, especially when young. Accidental damage can stress the plant and reduce its vigor.
• Not Hilling Enough: If your mounds aren't high enough, some tubers near the surface may still be exposed to light, leading to greening. Ensure the final mound provides adequate coverage.
• Introducing Weed Seeds with Material: If using straw or hay, make sure it's true straw and not hay, which can contain grass seeds that will sprout into weeds in your potato patch. If using garden soil, ensure it's free of persistent weeds.

By being mindful of these potential pitfalls, you can ensure your earthing up efforts are truly beneficial for your potato harvest.

Can Hilling Harm Potato Plants?

Under normal circumstances and when done correctly, hilling does not harm potato plants; it helps them thrive. However, if mistakes are made, there can be some negative consequences.

Potential harms from improper hilling:

• Stunted Growth: Burying all the leaves during hilling will inhibit photosynthesis, leading to severely stunted growth or even the death of young plants.
• Root Damage: Being too aggressive with a hoe or shovel during hilling can damage the shallow root system of the potato plant, stressing it and impacting its ability to absorb water and nutrients.
• Compacted Tubers: As mentioned, heavy, compacted soil can restrict tuber expansion, resulting in smaller or oddly shaped potatoes.
• Increased Disease Risk: In extremely wet conditions, very tall, dense mounds of heavy soil around the stems could potentially trap too much moisture, creating an environment conducive to some fungal diseases, though this is less common than root rot from overall poor drainage.

Always approach earthing up with care and pay attention to your plants' response. With proper technique, hilling is a simple yet powerful tool for maximizing your potato harvest.