Sunday, June 19, 2016

Why Do I Hill My Potatoes?

A kind reader asked why it is necessary to hill potatoes.  It's a good question and one I've heard asked many times.

Potatoes (the tubers we eat) grow very close to the surface of the soil in which they are planted.  Even though they may have a thin covering of soil, the sunlight that gets through to the forming tubers causes them to develop solanine.  That's the green coloring you sometimes see on potatoes.  And which is toxic to humans in large doses.  (That doesn't mean if I come across a green spot on one of my potatoes, I toss it in the compost.  Most likely I'll cut the green area off and use the rest of the potato.)  But generally speaking, finding potatoes that are green because of the solanine is not a good thing, and renders the potato inedible according to most potato growing experts.

Be aware that the toxicity of solanine affects some people more than others so you do not want the potatoes you grow in your garden to become green.

How to avoid this?  By hilling your potatoes.

Hilling keeps the light away from your developing tubers.  Potatoes form close to the surface of the soil so you want to "bury" them to a good depth.  Also, the more soil you pile around the plants, the more the formation of tubers is encouraged.

When I plant my potato eyes (or sets as they are also called) I go down the row of tilled soil with a broad hand hoe and make a furrow a couple of inches deep.  I place the eyes in the furrow about 12" apart, then using the hoe again bring soil from each side of the furrow over the eyes making a slight mount which I tap down lightly with the flat side of the hoe.  That's all I do until my first hilling.

You can grow potatoes without hilling.  This can be done by planting your potato eyes in a trench at least 7" or 8" in depth and then covering with soil leaving a slight mound on top of the row.  This method, to me, entails much more work both when planting and harvesting (and produces a smaller yield).  When harvesting you literally have to dig down into the (often compacted) soil to get to your potatoes.  If you hill by pulling loose soil up over the growing plants, you harvest the potatoes by turning over the looser soil which is much easier.

You can also grow your potatoes by placing a thick mulch of straw up around the potato plants in the same way you would the soil.  There are two advantages of using this method.  1)  You don't have to "dig" the potatoes at all at harvest time.  You just pull the straw away to gather the potatoes.  And, 2) the potatoes are much cleaner than if they were grown in soil.

Over the years, I've experimented planting my potatoes in both straw and soil.  Each time I've done this I've found the straw mulched potatoes yield only 50% of the quantity of those grown in the soil.

When is the proper time to hill your potatoes if you choose to grow them that way?  (Or when do you pile more straw on the emerging plants?)  Check five different sources on the subject and you'll find five different recommendations.

Although my plants got away from me this year because the rain and muddy soil kept me from working in the garden, I like to do my first hilling when the plants are small . . . about 6" high.  I nearly bury them in the soil I bring over them.

Then my second hilling is done again when the plants are showing approximately 6" more of growth.  The final hilling is done about two weeks later, although by this time the plants are so tall that I have a hard time finding more soil between the rows to use, and it's also hard to keep the soil from falling right back down the steep slope now formed up to the top of the plant.

Other sources say to do your first hilling when the plants are 8"-10" high and a second and final hilling 2-3 weeks after that.

As with so much of gardening, you have to experiment to see what works in your particular soil and climate conditions.  For instance, if you can get potatoes to grow well using the mulch method, what a joy to have clean potatoes straight out of the garden, but if you have a wet year, the mulch makes a desirable environment for the proliferation of slugs, slugs, and more slugs.  (Slugs which will dine voraciously on your potatoes!)

This information certainly isn't meant as "the-end-all-be-all" of why or how to hill potatoes but rather my personal experience I have to offer after many years of successfully growing potatoes.  

Just don't ask me how to grow a full-sized, red, ripe tomato up here near the tundra!


Michelle said...

I had never understood about hilling potatoes (and where tubers were formed!) before this year, so I'm hilling this year for the first time. Not many of my sets survived and I've not grown potatoes every year, but I'm looking forward to seeing a better production this year!

Rain said...

Wonderful post! I'm bookmarking it for my future garden! :)

Kev Alviti said...

Great post. I half heartedly hill mine each year, although I've not bothered with spuds this year and put tomatoes instead. As for green potatoes I know many farmers who have no lights in their potatoes sheds as if someone leaves a light on by accident then it can cost thousands in damage as the spuds start turning green in no time at all.

Bobbie said...

Mama Pea,
THANK YOU! You answered my questions. My potatoes may be lost because they are so tall, but I'll be heading out there immediately and try to throw some dirt over them. They are surrounded by weeds, so hopefully the weeds will help to hold the dirt in place. I am using raised mounds this year, so I understand the problem of dirt falling off. btw, I had no idea that the green part on potatoes is toxic to humans. Yikes! As we say in gardening - "Live and Learn"
Heartfelt appreciation on this great post and answering my question so thoroughly. I'll definitely try again next year using this method.
Happy Day To You ~ Bobbie

SmartAlex said...

I hill mine but not religiously. I have never found any difference in yield, however it does keep the potato patch from being a tumbled down mess because it supports the plants. If I run out of soil I bring in compost. So you are also amending your bed for next year.

Mama Pea said...

Michelle - Sending good luck wishes that you get a really nice harvest of spuds this year. Why do you think some of your sets didn't make it? Too much moisture? They will rot easily if the soil is too wet. Bummer.

Mama Pea said...

Rain - I hope the information will be of help when you plant those potatoes. Next year?

Mama Pea said...

Kev - Thank you! Hilling potatoes isn't my most favorite job, but I do believe it reaps benefits for me . . . so I keep doin' it! Good luck with your tomatoes.

Mama Pea said...

Bobbie - You're very, very welcome. I got a little long-winded, but tried to say it all intelligently.

It will be interesting to see what kind of a harvest you get from your (kinda sorta) un-hilled potatoes. It may turn out great! Who knows?

Mama Pea said...

SmartAlex - Using compost is a great idea. Any garden soil benefits from an addition like that!

Potato vines can get huge, heavy and kinda floppy, can't they? I never thought (dummy me) about the hilling helping to support them. Duh!

Your gardens are GORGEOUS. Picture perfect!!

Rain said...

I don't think so because we're renting and I can't dig up a spot for them. I think next year will be a container garden. Potatoes will wait until I have more land!

Annie's Journal said...

Thank you Mama Pea for this post on hilling potatoes. I had a vague idea but you explained it so well based on your experience. I've learned from you and I'll definitely put that into practice:) Blessings to your family this week.

Mama Pea said...

Annie - You're very welcome. As gardeners we all have to figure out through trial and error what works for us in our own location. All I can do is pass on what I've learned and hope it helps a small bit for others.

Our weather is going to be a lot cooler than this past week which will feel good to us humans, but the garden sure did like last week's hot spell!

Sandy said...

Mama Pea,
I liked what you typed above on planting potatoes. We use tires, with a good potting soil inside the circumference of the tire. We make sure to hill the soil before planting our eyes. Then place a fine layer of straw over the soil. As the potato grows we continue to throw straw over the top of the green area until it's grown over two layer tires. Making hills in your soil makes it so much easier to locate your potatoes at harvest time. I have found with all of our rain only a handful of potatoes are actually growing. :-(
The rain more than likely caused root rot.

I heard over the news this weekend MN had severe weather,and worried about you and yours. Are y'all okay?


Susan said...

Who knew? I read this and went out and hilled up my taters even more!

Mama Pea said...

Sandy - I know many people very successfully grow potatoes in tires as you do. It's a great way if you don't have a lot of space for rows in a garden. Sorry to hear your crop this year has been hampered by the rain. The eyes do rot quickly under wet conditions.

We made it through the storm in good shape compared to others. Roads washed out, trees blocking other roads and power outages in many areas.

Mama Pea said...

Susan - Just goes to prove you're never too old to learn. Did I just say you're old? No, no, I didn't mean that! (Besides you know darn good and well you're a whole ten years younger than me, you spring chicken!)