A Guide to Planting the "Earth Apple" for Success
How planting depth and method determine your harvest of this Andean superfood
Imagine a root vegetable that tastes like a sweet, juicy apple, looks like a slender sweet potato, and offers the crisp freshness of jicama. Meet Yacon (Smallanthus sonchifolius), the Andean superfood taking the gardening world by storm. But this exotic gem holds a secret: its bounty isn't a single root, but a complex underground system where planting strategy is everything. Getting the method and depth right isn't just a detail—it's the key to unlocking a generous harvest of its coveted, low-calorie, prebiotic-rich storage roots.
This article will delve into the science of planting yacon, exploring how a simple decision—how and how deep to place its "seed"—can determine the success of your crop.
Similar to apple and jicama
Native to the Andes mountains
Low-calorie, prebiotic-rich
To understand yacon planting, you must first understand its unique underground architecture. Unlike a carrot, which grows from a seed into a single taproot, yacon grows from a rhizome.
This is the "seed piece" you plant. It's a fleshy, underground stem that stores energy, much like a potato. Its primary job is to produce shoots upward and roots downward.
These are the prize! These large, sweet, tuberous roots develop from the rhizome as the plant matures. They are not the same as the rhizome; they are for carbohydrate storage and harvest.
The area where the rhizome connects to the base of the stem is crucial. This region is a hub of growth activity, where new roots and shoots are initiated.
The Central Question: How do we manipulate the planting process to maximize the number and size of these storage roots? The answer lies in the depth and orientation of the rhizome at planting time.
A pivotal study conducted by researchers at the National University of San Martín in Peru sought to answer this question definitively . Their experiment was designed to measure the direct impact of planting depth on yacon's growth and yield.
National University of San Martín, Peru
Impact of planting depth on yacon growth and yield
The researchers set up a controlled field trial with a clear, replicable process:
Healthy, uniform yacon rhizomes, each with at least two visible buds ("eyes"), were selected.
The field was divided into plots with four planting depths: 2cm, 5cm, 10cm, and 15cm.
All rhizomes were planted horizontally, with buds facing upwards, spaced 1 meter apart.
Measurements included sprouting rate, plant vigor, and final yield at harvest.
The results were striking and painted a clear picture of yacon's preferences.
| Planting Depth | Days to Emergence | Sprouting Success Rate (%) | Early Plant Vigor (1-5 scale) |
|---|---|---|---|
| 2 cm (Shallow) | 18 days | 98% | 4 (Very Good) |
| 5 cm (Medium) | 22 days | 95% | 5 (Excellent) |
| 10 cm (Deep) | 28 days | 85% | 3 (Good) |
| 15 cm (V. Deep) | 35 days | 70% | 2 (Fair) |
Analysis: Shallow planting (2 cm) led to the fastest and most reliable emergence. However, the 5 cm depth produced the most vigorous young plants. The very deep planting (15 cm) significantly delayed and reduced sprouting, as the young shoots had to expend immense energy just to reach the surface.
| Planting Depth | Avg. Storage Roots per Plant | Total Yield per Plant (kg) | Avg. Root Size |
|---|---|---|---|
| 2 cm (Shallow) | 12 | 2.1 kg | Medium |
| 5 cm (Medium) | 15 | 3.2 kg | Large |
| 10 cm (Deep) | 11 | 2.4 kg | Medium-Large |
| 15 cm (V. Deep) | 8 | 1.5 kg | Small |
Analysis: This is where the "sweet spot" became undeniable. The 5 cm planting depth consistently outperformed all others, producing not only the highest number of storage roots but also the greatest total weight and largest individual root size. The shallow planting led to a higher number of smaller roots, while deep planting restricted the plant's ability to produce a bountiful harvest.
| Planting Depth | Rhizome Cluster Size | Stability in High Winds |
|---|---|---|
| 2 cm (Shallow) | Wide, near surface | Poor |
| 5 cm (Medium) | Compact, well-anchored | Excellent |
| 10 cm (Deep) | Compact, deep | Good |
| 15 cm (V. Deep) | Very compact, very deep | Excellent |
Analysis: A crucial, often overlooked benefit of the 5 cm depth is plant stability. The rhizome cluster develops in a way that provides an excellent anchor, preventing the tall yacon plants (which can reach over 2 meters) from toppling over in strong winds.
The 5 cm planting depth consistently produced the best results across all measured parameters, making it the optimal choice for yacon cultivation.
Whether you're a research scientist or a home gardener, these are the essential "tools" and materials you need for a successful yacon planting.
The "living seed." Must have at least 2-3 buds (eyes) to ensure a strong shoot.
Yacon hates "wet feet." Loamy soil rich in organic matter prevents rhizome rot.
Provides a slow-release nutrient source for this heavy-feeding plant.
A mental (or physical) marker to ensure the rhizome is laid flat, not upright.
Crucial for consistency! Ensures the all-important ~5 cm planting depth is achieved.
Conserves soil moisture, suppresses weeds, and protects the shallow roots.
The science is clear: when it comes to planting yacon, precision pays. While the plant is resilient, its potential is maximized by a simple, evidence-based approach. The golden rule is to plant the rhizome horizontally, at a depth of approximately 5 centimeters (about 2 inches), in rich, well-drained soil.
This method encourages strong, stable growth, optimal root development, and ultimately, a maximized yield of those crisp, sweet, and health-promoting storage roots.
So, the next time you hold a yacon rhizome, remember you're holding the key to an underground treasure chest. Plant it with knowledge, and you'll be rewarded with a bounty fit for an Inca emperor.