Apart from stabilizing the plant, soil protects root system from sudden fluctuation in temperature.
Spaces among soil particles has water, oxygen and nutrients that help to break sugars, carry nutritional elements and has great contribution in photosynthesis.
Nutritional requirements of plants differ from one another. Edible plants like sweet potatoes are heavy feeders, so need organic rich soil. Without choosing best soil for sweet potatoes you shouldn’t expect a good yield.
Being a root vegetable, sweet potatoes grow large in sandy loam soil. It is a combination of 60 percent sand, 10 percent clay and 30 percent silt.
This growing medium drains water well and allows the roots to grow stronger with quality yield.
How Does Soil Affect Plant Growth?
Well-aerated, well-drainage and fertile soil are key to grow sweet potatoes with good yield.
Apparently, as mentioned above sweet potatoes (a root vegetable) need soil that drains well and rich in organic matter.
Well-aerated soil means, the growing medium should allow the air from the atmosphere to enter the root system easily. To make it possible, spaces between soil particles is essential.
In case, the soil isn’t well-aerated and blocks oxygen flow to roots, then the plant growth will be slowed.
Well-drainage potting soil helps to remove excess water and hold the moisture, so that the plant can consume water through roots. Choosing wrong soil for sweet potato can clog excess water and result in root rot.
Read this: How Often to Water Sweet Potatoes?
Soil pH affects the nutrients in the soil and how the plant absorbs them. Sweet potato prefers slightly acidic soil and most gardening experts recommend soil test before planting.
Not just stabilizing, soil insulates the plant from higher temperatures. (Source)
Best Soil for Growing Sweet Potatoes
Not choosing the right potting soil for sweet potatoes will often result in issues like overwatering, root rot, underwatering, stunted plant growth and low yield.
So, what are the characteristics that you need to look on before choosing the growing medium.
Will it be same when growing in container Vs outdoor?
Below mentioned are essential elements that you need to look on to while choosing soil.
If your container soil or garden soil fulfills these characteristics, then your sweet potato plant will thrive.
#1 Sandy Loam Soil
As mentioned above, root vegetable plants like sweet potatoes thrive in sandy loam soil. This soil is light with airy texture, which allows the oxygen to easily reach roots.
Though it drains water efficiently, this soil also has ability to hold required moisture to the plant.
Spaces between soil particles also allow absorbing nutrients from the organic matter that you added while planting.
You can either sandy loam soil or potting soil from the gardening store or make your own by adding 50 to 70 percent of sand, 20 percent of clay & silt. Also include 20 percent of organic matter to the growing medium. (Source)
#2 Fertile Soil
After soil test if you find the nitrogen percentage is less compared to phosphorus and potassium, then add natural fertilizers rich in nitrogen. This will help to increase quality and yield of your crop.
Based on the soil test results, you should add balanced NPK ratio fertilizers. Using high amount of nitrogen can apparently impact the yield. All three nitrogen, phosphorus and potassium are needed for healthy plant.
Lush foliage with few roots is a sign that you’re using high levels of nitrogen.
If you’re growing sweet potatoes in container, then add compost or vermiculite to the soil before planting. This will eventually improve NPK ratio and improve drainage ability of the soil.
#3 Soil pH for Sweet Potatoes
pH of the soil impact the ability to dissolves and absorb nutrients to the plants.
Sweet potato plant prefers acidic soil with pH range 5.5 to 6.8. You can add lime stone if the pH it too low.
Optimal pH range will help the plant to produce high and quality yield.
Also Read: Why Cabbage Leaves Turning Yellow?
Important Note: Overwatering your plant results in root rot, yellow leaves and stunted growth are signs of this disorder.
Best Soil for Sweet Potatoes in Containers
You can grow tons of sweet potatoes indoors, with rich potting soil mixed that is well drained and well aerated.
As mentioned above, you can buy potting soil mix from online store or make your own by adding sandy loam soil with compost and perlite to improve aeration.
Unlike other plants, you can grow sweet potatoes from leftovers. Choose sweet potato that has no damaged spots. Cut into pieces larger than the mouth of glass container. Position the tuber in a glass container, in a way that toothpicks hold the tuber and as they rest on edges of the glass container.
Change the water couple of days. After few days, you’ll find shoots pop-up over sweet potatoes. Allow them to produce leaves.
Once, the sprouted slips produce leaves, cut the slip and place in another glass container filled with water. This will allow the sprouted slips to grow roots. When roots appear 1 inch long, this is the time when you can plant the slips in container filled with potting soil.
Also Read: How Often to Water Kale at Home?
Sweet Potato Growing Mistakes You Must Avoid
Your sweet potato plant loves warmer climate. It can tolerate cold but night soil temperature shouldn’t drop below 55F.
- In this case, if you opt to grow the variety that takes longer time and winter or frost in your region is round the corner, then this mistake will cost you the yield.
- Choose sweet potato varieties that take less time to mature.
Adding too much fertilizer to the soil will damage the root system. Organic matter that you’re asked to add while planting will be enough for 3-4 weeks.
In growing season you can add balanced liquid fertilizer.
As mentioned prior, your potting soil must have 50-60 percent sand. This will improve drainage ability of the growing medium.
Without this, the plant may stand in water for longer time, resulting in root rot.
Sweet potato plant loves to grow in full sun with adequate amount of water. Ensure the plant gets direct sunlight for about atleast 6 hours.
While harvesting, don’t damage the tubers. Be gently and prefer to harvest once the tuber grows less than 8 inches. Remove tubers that are damaged or attacked by pests.
Fine sandy loam soil with added organic matter is best suited soil for growing sweet potatoes in containers or outdoors.
To grow outdoors, gardening experts recommend raised garden beds. Growing them on ground may unnecessarily shade other plants.
Your garden bed must include organic matter with crumbly growing medium (soil). Mulching garden bed with hay grass will help to retain moisture for longer time on hot days.