With more and more people living in cities with limited space outdoors for gardening, many urban gardeners are turning to container gardening. This practice is great for herbs and other shallow-rooting plants, but root vegetables do not always grow well in containers. Potatoes need plenty of fertilizer to grow well. Learn how to make your own homemade fertilizer for potatoes today.
Potatoes are difficult to grow in the garden, and quite challenging to grow in a container. Regardless of where you plant them, there are several steps that you can take to minimize the risks and maximize the yield of your potato plants.
Growing your own potatoes
Before I begin this article, I should let you know that if you would like more information about growing your own potatoes, please read my article How to grow your own potatoes. This covers planting, preparing seed, growing, harvesting and storage, and more about this great vegetable.
Preparing soil to plant potatoes
Potatoes prefer a deep, loose, acidic soil. If you want big, firm and flavourful potatoes, you’ll need to prepare the soil ahead of planting and at planting time.
If you plan to grow your potatoes organically, there are two ways to prepare the soil: cover crops and organic fertilizers.
Planting cover crops before potatoes
A cover crop is one that is grown primarily to protect and enrich the soil; they are typically off-season crops planted after harvesting the primary crop and they may even grow over the winter. A cover crop helps to manage soil quality and fertility, moisture content, weeds, pests, diseases or biodiversity within the garden.
Legumes are the most effective cover crops for potatoes as they leave nitrogen behind in the soil; they should be grown in the fall and plowed under in the spring.
Organic fertilizer for growing potatoes
An alternative to cover crops is top-dressing the soil with an organic fertilizer; this process means that the fertilizer sits on top of the soil rather than being blended into the soil as for most vegetable crops.
In order to ensure the acidity of the soil, some gardeners also use a vinegar solution before or after planting. Oak leaves, pine needles or sawdust will also make the soil more acidic. It’s best to have a soil sample tested before making any adjustments or additions to the garden.
Preparing seed potatoes
Using high-quality seed potatoes will boost your choices of a good yield; place them in a cool, light, and frost-free area with the most ‘eyes’ possible exposed. Over the course of the next 2-4 weeks, the eyes will sprout.
Cut the larger seed potatoes so that each piece has at least one large sprout. Up to three sprouts per piece is acceptable and smaller potatoes can be left whole if necessary.
Any potato that has eyes that have not sprouted – or at least swollen – will probably not develop a plant and should be discarded, along with any that show signs of rot.
Some gardeners add sulfur powder to their seed potatoes after cutting them; it provides a natural protection against disease. It should be applied while the cuts are fresh and still damp.
The cut seed potatoes should rest for a couple of days to skin over before planting.
Planting the potatoes
Deep holes or trenches are best for planting potatoes; they should be 10”-12” deep and, as you fill in the soil, it should only loosely cover the seed potato.
To allow for a higher yield per plant or larger potatoes, allow a minimum of 12”-14” inches between holes or between plants in the trench. Tighter spacing will produce smaller tubers.
Potatoes require a lot of phosphorus when rooting, so you can sprinkle ¼ cup of bone meal (which is very high in phosphorus) in each planting hole. Place one piece of seed potato in each space and make sure that all the shoots are facing up.
Hilling or moulding up the potatoes
When the shoots are 10”-12” tall, they should be fertilized and covered with a hill of soil nearly to the top of the shoot. When they’ve grown another 8”-10”, fertilize and hill them again.
Large hill of loose soil will produce a better crop but you should never hill potatoes that have started to bloom – you could sever the shoots and kill the new potatoes.
You should keep a close watch for potato blight during the summer months as this can devastate the entire crop if left unattended.
When the blossoms die, dig up a test hill – you’re looking for a hard potato with a thick skin that is firmly adhered. If your crop is ready, sever the vines and after a week or two, harvest the potatoes.
Organic fertilizers which are good for growing potatoes
In addition to composted kitchen and yard waste, there are several other types of homemade organic fertilizers:
Acid-loving plants generally grow well if sprinkled with coffee grounds. The dried grounds can be sprinkled on top of the soil or use a soil drench; soak 6 cups of coffee grounds in 5 gallons of water for 2-3 days then saturate the soil around your plants.
Be careful not to overuse coffee grounds when planting potatoes as the grounds contain a lot of nitrogen, which isn’t necessary for a good potato yield.
Composted and aged manure can be an excellent fertilizer; you can let it steep in a permeable cloth bag for a few days before applying it to the soil to condition it before planting.
You can also create a manure tea by steeping the composted and aged manure in a bucket of water for 2-3 days; dilute the tea before applying to avoid burning the roots and the foliage.
Fish emulsion fertilizer
This fertilizer has a strong smell –WOW! – not surprising as it’s made of rotting fish.
Into a large 55-gallon drum mix the correct ratio of water to fish based fertilizer and allow the mixture to still for the desired amount of time. Be careful when selecting the fish-based fertilizer as many are high in Nitrogen which is not what we want. The ideal ratio for potato fertilizer is 10-20-20 of N-P-K.
Fish emulsion fertilizer can be applied to the soil around the plants at a rate of 3 gallons of liquid per 100 square feet of garden; diluted at 1 tablespoon of emulsion per gallon of water, this solution can be used weekly to water the growing potatoes.
Homemade fertilizer for potatoes
Many gardeners have successfully used a homemade mixed fertilizer to improve the health and yield of their potato plants. You will need some or all the following:
Combine 4 pounds of cottonseed meal, 2 pounds of bone meal, 4 pounds of sulphate of potash and 1 pound of kelp meal in a large airtight container; this will be enough fertilizer for a 40’ row of potatoes.
If you can only get one or two of these that is ok. It is much better to have some type of fertilizer than none.
Place the homemade fertilizer at the bottom of the trench or work it into the soil with a rototiller before planting the seed potatoes. Then cover the seed potatoes with at least 6 to 8 inches of the finely tilled soil to keep them safe from frost and sunlight.