If you’re new to growing potatoes, you might wonder about the best way to hill them. Do you cover leaves when hilling potatoes? This is a common question, and the answer is crucial for a healthy crop. Hilling is the process of mounding soil around the base of your potato plants as they grow. It’s a simple technique with big benefits, but doing it wrong can actually hurt your plants. Let’s look at the right way to create that protective soil barrier.
Do You Cover Leaves When Hilling Potatoes
The short and most important answer is no, you should not cover the leaves. When you hill potatoes, your goal is to cover the stem, not the foliage. Burying the leaves can cause several problems. It blocks sunlight, which the plant needs to make energy. It can also trap moisture against the stems and leaves, creating a perfect environment for fungal diseases to start. The top leaves should always remain above the soil, free and clear.
So, what exactly are you covering? You are targeting the new, tender stem growth that emerges from the seed potato. This stem, once buried, will produce more roots and, most importantly, more tubers along its buried length. The leaves are the factory; the buried stem is the production line. Keeping this distinction clear is the key to successfull hilling.
Why the Protective Soil Barrier Technique Matters
Hilling isn’t just busy work. It serves three vital functions for your potato plants. Ignoring this step can lead to a disappointing harvest, so understanding the “why” makes the “how” much easier.
- Prevents Greening: Potatoes tubers that are exposed to sunlight will turn green. This green color indicates the presence of solanine, a natural toxin that can make you sick. Hilling ensures tubers develop in complete darkness, safe under a thick layer of soil.
- Encourages More Tubers: Potatoes form on lateral stems called stolons. By burying a portion of the main stem, you give the plant more space to send out these stolons. More stolons means more places for potatoes to grow, potentially increasing your yield.
- Improves Drainage and Weed Control: The mounded soil improves drainage around the plant’s base, reducing the risk of rot. It also helps smother and outcompete weeds that would otherwise steal nutrients and water from your crop.
The Right Way to Hill Your Potatoes: A Step-by-Step Guide
Now that you know what not to do, here’s the correct method. Timing and technique are everything. You’ll typically hill your potatoes two to three times during the growing season.
- First Hilling: Wait until your plants are about 6 to 8 inches tall. Gently use a hoe or your hands to pull loose soil from between the rows up around the base of each plant. Cover about half of the exposed stem, leaving several sets of leaves uncovered. The goal is to bury 3 to 4 inches of stem.
- Second Hilling: About two to three weeks later, after the plants have grown another 6 to 8 inches, repeat the process. Again, pull soil up to cover the newly exposed lower stem, leaving all the upper foliage untouched. Your mound will get progressively bigger.
- Final Hilling (Optional): In some cases, you might do a third light hilling if the plants are very vigorous or if soil washes away. By this stage, the plants are often beginning to flower, which is a sign that tuber formation is in full swing.
Always use loose, fine soil for hilling. If your garden soil is heavy clay, consider having a bucket of compost or a bag of potting mix on hand to use for the hilling mounds. This lighter material is easier on the stems and better for tuber development.
Best Materials for Building Your Hilling Mounds
While garden soil works, many gardeners use alternative materials for the protective soil barrier. These can offer additional advantages like better moisture retention or fewer weeds.
- Straw or Hay: Excellent for a method called “straw mulching.” You can hill with loose straw instead of soil. It keeps tubers completely dark and makes harvesting incredibly easy—just pull the straw back. Ensure it’s seed-free to avoid a weed problem.
- Compost or Leaf Mold: These are fantastic choices. They add nutrients directly to the root zone as you hill and improve soil structure. They are usually light and easy to work with.
- Weed-Free Mulch: Shredded leaves or other fine mulch can work, similar to straw. The key is that it must be thick enough to block all light from reaching the developing tubers.
Common Hilling Mistakes to Avoid
Even with good intentions, it’s easy to make a error. Here are the most frequent pitfalls so you can steer clear of them.
- Hilling Too Early: If you hill when the plant is just a sprout, you might cover it completely and kill it. Wait for substantial growth.
- Using Clumpy, Wet Soil: Heavy, wet soil can damage stems and compact, making it hard for tubers to expand. Let the soil dry out a bit first.
- Not Hilling Enough: A tiny mound won’t provide adequate coverage. Your final mounds should be 6 to 8 inches high. Shallow hilling leads to green potatoes.
- Damaging Roots or Tubers: Be gentle when pulling soil. Avoid driving your tool too deeply right next to the plant where early tubers may be forming.
What to Do If You Accidentally Cover the Leaves
Don’t panic if you slip up and bury a few leaves. If you notice it right away, simply brush the soil away from the foliage. If the plant is small and only has a few leaves covered, it will likely recover on its own as it grows upward. The main risk is disease from prolonged dampness, so try to correct it when you see it. The plant is more resilient then we sometimes think.
FAQ: Your Potato Hilling Questions Answered
Q: How deep should the final hill be?
A: Aim for a final mound that is 6 to 8 inches deep from the original ground level. This ensures tubers are well buried.
Q: Can I use grass clippings to hill potatoes?
A: Yes, but with caution. Use only thin layers of dried grass clippings. Fresh, thick mats of clippings can heat up as they decompose and may also mat down and shed water.
Q: Do I stop hilling when the plant flowers?
A: Flowering is a good signal that major growth is slowing. You can do a final, light hilling at this stage if needed, but focus on maintaining the existing mound. After flowering, the plant’s energy is going into bulking up the tubers.
Q: What if my soil is very rocky?
A: Rocky soil can cause misshapen tubers and make hilling difficult. Consider growing potatoes in a raised bed filled with a good soil-compost mix, or use the straw mulch method exclusively to avoid the rocks altogether.
Q: Is the protective soil barrier technique necessary for all potatoes?
A> It is critical for traditional garden planting. Some alternative methods, like growing in deep containers or potato bags, have the “hill” built in as you add soil to the container itself.
Mastering the hilling technique is what separates a mediocre potato harvest from a great one. Remember, cover the stem, not the leaves, and build a generous, light-blocking mound. By providing this protective soil barrier, you give your plants the darkness and space they need to produce a bountiful, healthy crop of tubers. With a little practice, it becomes a quick and satisfying part of your gardening routine, leading to those wonderful moments of digging up your own homegrown potatoes later in the season.