Burying the soil to prevent cold is a common method. Generally, when the low temperature in winter reaches -15°C, a soil covering of around 20 cm is recommended. If the temperature drops to -17°C, the soil covering should be increased to 25 cm. The full burial method on the ground involves covering the soil without digging trenches. The thickness of the covering soil depends on the local absolute minimum temperature and the cold resistance of the specific variety. Lower temperatures require a thicker soil cover. For some cold-hardy varieties, such as Kyoho and white banana, the covering soil can be slightly thinner.

Regarding the plant form, the canna lily is a self-sufficient species, but planting multiple canna lilies is recommended for optimal harvests. The recommended spacing between canna lily plants is 6 to 8 feet. Canna lilies are known for their hardiness.

The growth pattern of the canna lily is moderate, and the plant thrives in sunny conditions.

In summary, the key points are:

1. Burying soil to prevent cold:
2. 20 cm soil cover for -15°C, 25 cm for -17°C
3. Full burial method without digging trenches

4. Thickness depends on local temperature and variety's cold resistance

5. Canna lily plant characteristics:

6. Self-sufficient, but multiple plants recommended for better harvest
7. Recommended spacing: 6-8 feet
8. Very hardy
9. Moderate growth, requires sunny conditions

The revised content maintains the original semantics while improving the reading experience through adjusted word order and concise expression.

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