How to Grow Butternut Squash

Days to germination: 5 to 10 days
Days to harvest: 90 to 100 days
Light requirements: Full sun
Water requirements: Regular watering
Soil: Fertile and well-drained
Container: Possible in large containers

Introduction

Butternut is one of many different kinds of winter squash, with a distinctive pale yellow and pear-shaped fruit. Inside, the firm flesh is orange and distinctly sweet.

It’s never eaten raw, but the the flesh can be cooked in a variety of ways once the seeds have been scooped out. Baked or roasted is the most common. Being orange inside, its no surprise that butternut squash is very high in vitamin A. You will also get potassium, vitamin C, manganese and a large dose of fiber.

Starting from Seed

Butternut squash need warm soil to germinate so you are better off starting seeds indoors, though you can also direct seed outside once the weather warms up.

Plant your seeds in larger (3″) seed pots rather than flats, with the seeds about an inch under the soil. You can plant 2 or 3 in each pot, to transplant together in hills. Keep your pots somewhere sunny and warm or they may take a long time to sprout. Get them started around 3 weeks before your last frost date.

Each butternut squash plant will produce several large squash, so you won’t likely need more than 3 or 4 plants.

Transplanting

Your seedlings should go out about 2 weeks after your last frost has passed.

Dig your soil to prepare for planting and add fertilizer or compost. Choose a location that will have full sun and allow a lot of space for the vines. Each hill should have 3 feet of space around it.

If you are putting seeds straight into the garden, you’ll be planting them at the same time as you would put out the transplants. They will not germinate or sprout in cold soils. Plant 4 or 5 seeds in a small hill, and thin down to 2 or 3 after they have sprouted.

Butternut can be grown upward on a fence or trellis if you don’t want to have vines all through your garden. If you plan on training them up this way, you can plant your seedlings just 2 feet apart. In this case, don’t plant them in little groups, but rather just one plant every 2 feet. Be prepared to add extra support when those large fruits start to grow.

Growing Instructions

Like cucumbers, squash vines will first have a round of male-only flowers come to bloom before the female ones do. So don’t be alarmed if none of the first blossoms set any fruit. They aren’t supposed to.

For plants growing on a trellis, you will have to take care to protect the squash as they get larger. The plant won’t be able to support them up in the air on its own. Various slings or nets can be fashioned by the creative gardener. Pantyhose, old t-shirts, mesh produce bags can all be used to make a squash hammock. Just tie them to the trellis, not the vines.

As the season comes to a close, pinch off any new flowers and remove very young squash. You can help the plant divert its resources to finishing off the larger squash before winter by not letting any new ones get started.

Containers

Butternut is one of the larger winter squashes and not really ideal for container gardening. A container that is 5 gallons in size or larger would be adequate for 1 plant, though the vines will take up quite a bit more space beyond that. You can trellis container squash, but will have to make sure it is secure as the top-heavy trellis can topple over if it’s just anchored by a pot of soil.

Pests and Diseases

Healthy butternut squash plants can produce many pounds of food for you, but you will need to take care of them first. They are unfortunately susceptible to a number of potential problems.

The broad leaves can be attacked by squash bugs or striped cucumber beetles. Check your plants frequently and pick them off as you find them. They can hide in the blossoms, so look there too. Insecticide sprays can usually help keep them to a minimum. A tent of mesh over your young plants can protect them, just make sure you remove it when the flowers start to bloom.

Vine borers aren’t as obvious and they will eat into the stalks of the plants where you can’t see them. If your plants wilt even thought they are well watered, this is likely the problem. You can use some pesticides before they strike but once they are in your squash plants there is little you can do to save the plants.

Bacterial wilt is another possible cause for wilting plants, and it spread by the cucumber beetle. The leaves closest to the infection point will start to wilt first, and the it will spread through the plant. The vines will start to get misshapen and then die outright. You can’t treat wilt so pay close attention to the cucumber beetles in your garden.

One last threat is the common powdery mildew. You can get a white “powder” coating on the leaves if you get water on them every time you water the plants. Direct the water at the soil and it should prevent this from developing.

Harvest and Storage

On average, each squash will weight around 1 pound and each plant should produce 3 or 4 of them in a season.

As a winter squash, you don’t generally pick butternut until it has fully matured. Summer squash like zucchini are different as they can be picked and eaten while young. Watch for your maturity date, and check the fruits with a fingernail. The skin should be tough enough that a nail won’t cut into it.

A mature squash will be fine after a light frost, but its best if you can get your harvest in before your frost date. After a frost they won’t store as long though they will still cook up just fine.

For squash you are using right away, you can keep them in the refrigerator for up to 2 weeks. Cooked squash can be frozen but it will lose its firm texture after you thaw it out.

To store for a longer period of time, let your squash “cure” out in the sun for a couple of dry afternoons before putting them into storage. You should be able to keep them for a few months in a cool dry place.

38 Responses to “How to Grow Butternut Squash”

Mike Says:
May 15th, 2011 at 7:51 am
This was really helpful. Do you have any recommendations for how I can make an inexpensive trellis for my squash? This is the first year I’m growing it, and I’m not too sure what would work best. Is there a good companion plant for it?
Thanks!
-Mike
Salisbury Mils, NY
Anita Barrett Says:
May 27th, 2011 at 7:37 am
I have about 10 Squash plants that are huge. The runners are now quite long and producing quite a few squash. How do you regulate the amout of fruit on each runner and how long do you let them grow, at the moment they are look out of control. I live in spain.

Thank you
Chris Says:
July 30th, 2011 at 5:42 am
How do you know when they are ready to be picked and does it matter how long you leave it on the vine?
Rosemary Stanley Says:
July 30th, 2011 at 6:06 am
I also put them in my garden and the vines are unbelievable. will do the trellis next year. I have a plan for sturdy support and have to plan to support the fruit.
Jean Foltz Says:
July 31st, 2011 at 4:45 pm
not getting any flowers and vines are growing as they should. any ideas?
Administrator Says:
August 2nd, 2011 at 5:20 pm
Sometimes the vine grows for awhile first before flowering. But less sunlight also will generally mean less flowers, has it been cloudy? You could try a high potassium fertilizer.

Ideally you’ll want your squash to be ready to harvest just before your first frost date, with it being typically a 120 day plant. So long as you planted say 120-130 days before you’re first frost date, you should be fine.
Verna Says:
August 4th, 2011 at 4:57 pm
What causes the young squash to start out yellow and then die? We have some successful squash on the same vines.
Joanna Says:
August 8th, 2011 at 11:13 am
I have the same problem as Verna. I have one beautiful squash growing nicely, and all others get to about 1 inch in size, then turn brown and fall off. Any suggestions to the cause?
Fred Lamson Says:
August 17th, 2011 at 4:16 am
What causes the young squash to start out yellow and then die? We have some successful squash on the same vines.

#7
Pam Says:
August 20th, 2011 at 11:43 am
I was told to put hay or straw underneath my butternut that is on the ground as to avoid rotting. Is this necessary? Also, should I be rotating the squash periodically to encourage even coloration from the sun/discourage rotting? Thanks in advance
Nicky Says:
August 26th, 2011 at 5:33 am
I’ve the same problem as Verna and Joanna. Any tips?
Cyndi Burgin Says:
August 27th, 2011 at 4:57 pm
I planted 3 hills of butternut squash (purchased the seed) and I bought two b utternut squash plants. They ALL have squash that looks like Summer Squash! They are bright yellow! What happened?
Administrator Says:
August 28th, 2011 at 12:55 pm
Could be your butternut squash need to mature, their color deepens. Could be you just bought mislabeled plants. Squash leaves and squash blossoms are both bigger than summer squash. So that is an easy check.

To those who have had small squash drop off. That is most often the cause of incomplete pollination, though it can also be caused by some diseases or by drought. Try hand pollinating with a Q-tip.
laura Says:
August 30th, 2011 at 10:33 am
My butternut squash plants have just started to have the female blossoms and to be starting the butternut fruit part….I think that they have successfully been pollinated….if it is now 8/30 and the average first frost date is 9/8 for my area of NH, will there be time for the butternut squash to mature? How long will it take? does the 120 – 130 maturity rate apply to the whole plant and when it was planted or to the squash alone? I purchased mine late from an Agway and probably put them in the ground sometime in July. Same for my acorn squash although that one started producing the female plants a couple weeks before the butternut squash.
Administrator Says:
August 30th, 2011 at 12:17 pm
If you have frost on September 8th (which seems really early) you will not have time. This will vary, but in my experience female blossoms start appearing about halfway through the 120 day length. It will take 3-4 weeks for the fruits to grow in size, then 3-4 weeks for them to mature and ripen.

If they only just appeared for you, you need frost free weather until Halloween.

If you get early warning of a frost you can try covering your plants.
Meg Says:
August 30th, 2011 at 5:13 pm
I think we have bionic plants… I planted 2 plants back at the end of May or early June… we have about 10-15 fruit. The largest fruit are HUGE and weigh 3-4 lbs each.

My question is how do you know when they are ready to harvest… I am thinking when the green is gone and the whole fruit is nice and tan?
ruth Says:
August 31st, 2011 at 1:38 am
I would like to know the same as Pam do you need to put straw under your butternut squash, I also have heard to put a tile under it to stop is going mouldy with the wet weather. Thanks
Christine Says:
September 2nd, 2011 at 9:08 am
Its now beg of september, I have small round squashes, should I nip out the growing tips so that all energy goes into the fruit and also another blogger asked whether she should but straw under them, should we?
Thanks
Administrator Says:
September 2nd, 2011 at 1:11 pm
I’ve never put anything under my squash, but then again they don’t grow in low lying wet areas for me, if they did, maybe I would. I have a bigger problem with rabbits and squirrels leaving bite marks in them.
Administrator Says:
September 2nd, 2011 at 1:13 pm
@Meg, yes, you harvest when the color changes, with the stripes vanish and it matures to that normal beige color. Letting it stay on the vine longer will not hurt it.

Also, you can’t use it right away after harvesting, it needs a little time to ripen on the shelf. If you try to cut one up right after harvesting… be warned your hands will not like it.
Administrator Says:
September 2nd, 2011 at 1:22 pm
Oh, my favorite recipe with my butternut squashes is butternut squash risotto. It is so addictingly good, it is the reason I grow them in the first place.

Cut a squash (average size) in half and clean it out, bake it cut size down at 425 for an hour, remove and cool, then clean out the squash stuff, compost the peel (this can be done ahead).

Do all the below with a wooden spoon or spatula (plastic ends up not strong enough, metal gets too hot)

In a big tall pot melt half a stick of butter and 1 whole onion (chopped fine), cook over high heat until the onions softens. Add in 2 cups of arborio rice (has to be arborio rice specifically, other rice types will not work). Stir until the rice absorbs most of the butter. Pour in 1/2 cup of white wine, stir until absorbed. Reduce heat to medium. Stir in roasted squash and 2 cups hot chicken stock. mash it to work it in. when the rice absorbs all the stock, add more, and keep stirring. Stir, add stock, stir, add stock, as the rice absorbs the liquid, keep adding more in increments, while stirring. You stir for a long long time. This is a labor intensive dish. You’ll need 8 or so cups of stock probably, you can sub more white wine if you want for part of it. And water if you run out of stock, but stock is better.

When the rice is done (by taste, it is soft), add half a cup of grated parmigiana cheese (good stuff), mix it in, and serve. This will keep hot for a long time, so be careful, and people will try to steal it from you it tastes so good.
Deanna Says:
September 4th, 2011 at 10:07 pm
I have butternut squash in a huge clay pot. I have had many blooms and several fruit start but fail when about 2 – 3 in long. I also am plagued with powdery mildew. I live in S. FL and we are in the rainy season. I have also been plagued with those caterpillars similar to those you get on tomatoes, and they roll up in the underside of the leaf. Should I tear them out and start over now as we will be going into winter and drier weather? IF we get a FROST it will be Feb or Mar.
johnny Says:
September 5th, 2011 at 4:33 pm
I just ate the first of my squash tonight, the color and size were right, as was the grow time (planted mid to late May). It was very starchy, tasted more like a Kubocha. Any ideas on why?
Administrator Says:
September 5th, 2011 at 5:50 pm
They need to cure, off the vine, on the shelf, to ripen and get sweeter.

Also,t here is a chemical in them that’ll take the skin off your hands if you process them too fresh (like right off the vine). I highly do not recommend it.
nachum hirschel Says:
September 14th, 2011 at 1:37 pm
I live in Israel where we have very mild winters with no frost and some rain. Is it possible to plant winter squash in october and have it grow in the winter months.
Debra Says:
September 14th, 2011 at 2:21 pm
For Mike in NY and other who asked about trellis growing.
I used simple garden green coated fencing. I have an 11′ bed. I used three 6′ stakes (the metal rebar ones with the green plastic coating are nice and strong) along the bed woven to hold up 4-5′ of fencing. I poked the new leaves back and forth about every 6″ of vine. They put out long, thick tendrils that grabbed onto the fencing too. Easy and inexpensive! Caution to use the sling idea for heavier squashes like spaghetti. This is my first year, but my brother has grown like this for years. In the Northwest where we live, it also helps to keep the plants and fruit dryer to prevent the mold problem.
Pam Says:
September 15th, 2011 at 8:00 am
Sorry to step on toes; however, as the administrator did answer the question about putting straw underneath ground grown Butternut Squash I will for everyone. Just came from my garden and noticed the squash that is on straw is perfect; however, the stragglers I missed that are on the ground/grass are rotting secondary to the night dew/rain. I also gently rotated my squash periodically to prevent rotting (even ones on the straw)!!
susie Says:
September 17th, 2011 at 1:25 pm
we have butternut, hubbard, and burgess buttercup. last week we notice that teeth marks were on a small butternut. we have mouse traps all around everything but this looks to be rats. Yesterday I picked 7 butternut and a few of the others that all have teeth marks. we are very upset! Do I have to cut them to can or freeze them or can I still store them with the teeth marks. Should I clean the are with a bleach solution or will the plants rot sooner since the skin is broken???
Administrator Says:
September 17th, 2011 at 4:17 pm
Squash have their own self defense mechanisms, the wounds should scar over.

I would put the damaged ones at the top of the eating list though, because they may rot sooner, and if you see any discoloration or oddities on the inside, cut around that portion.

Remember also to still let them cure after picking, don’t cut them up right away.

Personally this year I took some poison, mashed it up in some peanut butter and put it out for whatever critter was eating mine – of course don’t do that if a random kid could wander into your garden.
Dee Says:
September 21st, 2011 at 3:42 pm
There were butternut squash growing in my back yard (I did not plant them) a friend saw this huge squash and figured it was ready to pick. I kept it inside for about 2 weeks and decided just tonight to cut it and cook it but, when I cut it open it was yellow inside rather than orange like store bought squash. Since it is cut, I am going to steam it but want to know is it ok to eat even though the inside is yellow or should I chalk this up as a loss and throw it out? There are other squash still on the vine and from reading the other emails I think I will leave these alone for a little longer. Thanks in advance for any responses.
flick Says:
September 24th, 2011 at 11:50 am
+just thought id add if youre in england and you have the squash on the ground would it be better not to put straw down as woodlice eat dry and rotting material and also get attracted to fruit/veg. i ask this because the blghters ate all my strawbs!!
Verna Says:
October 1st, 2011 at 3:42 pm
can raw butternut squash be frozen and what is the best way to do this?
Susan Says:
October 15th, 2011 at 6:06 am
We just picked our 40 squash grown on mounds in a neighbors corn field. We were delighted with the harvest but some are still a little green. We had to harvest them because the farmer plans to plow the field under. Will they continue to ripen off the vine? Should I put them in the sun?
Kerrie Says:
October 20th, 2011 at 6:18 pm
Hi from sunny Sonora in Mexico:

While not new to gardening, this is only the second time we have tried butternut squash. The first time, last year in the Guadalajara area, we had a courtyard garden with limited sunlight, and constantly fought the blight of mold on leaves. I was able to fight off death of the plant with a mist of diluted grapefruit seed extract, but eventually they were consumed.

We seem to have moved to butternut squash/pumpkin nirvana. It is the desert, constant hot sun included during what would be summer in the US, and people told us we could not start plants until late October. I told them they had better consult with our plants, which are doing extremely well, and growing like something out of a Hitchcock movie.

Here’s what I did: I put dry seeds into scalding hot water, about a minute after taking boiling water off the flame, on September 9. I let the seeds soak all night as the water cooled down, then in the morning scrolled them into a paper towel and kept them moist inside a glass. Three days later after an all-day trip out of town, I came back to full-blown plants, no mere sprouts, bursting out of the glass.

They never slowed down. My technique includes training them up a chain link fence, a formerly ugly feature of this property. I put them in at every two feet, put a stone circle about ten inches in diameter around each plant, then filled in everything outside the circle with deep gravel (fights ants, preserves moisture in soil). Most of them are now up to the top of the six-foot-tall fence. At forty days they were covered in emerging pollinated squashes.

I am wondering if I should take off about half the squashes? Some balloon up in size, others seem to not (there are too many to keep up with, we have about forty plants in order to cover the fence).

One other thing, I am feeding them with green tea. In case anyone is not familiar with it, you fill a large rubber barrel with a tight fitting lid with all manner of green cuttings – banana leaves, palm branches, weeds, as long as it’s green – fill it to the brim with water, then put the lid on it for two weeks in the hot sun. When you take the lid off, beware, the stench could knock you over. I continually add green waste to it, and water, and put it on the plants every day.

Is it odd to see such fast results with butternut squash plants? I am curious to hear feedback.

Thanks in advance.
Kerrie Says:
October 20th, 2011 at 6:41 pm
Sorry, one other step I forgot to add: as is done with pumpkin seeds, I lightly filed the edges of the butternut squash seeds before germinating them.
Judy Fifer Says:
October 25th, 2011 at 8:06 pm
I live in north Florida and I don’t know when to plant butternut squash seeds, it gets really hot for a 4 month period here and would enjoy trying to grow my own butternut squash. Please let me know what I should do. I just finished enjoying a butternut squash and saved the seeds for future growth.

Thanks

Judy Fifer
Jan van der Walt Says:
December 8th, 2011 at 9:54 am
My butternut creates flowers & small fruits. But as soon as the flower dies off the fruit turns yellow and die off. I planted seeds saved from a butternut. Other vegs in my garden grows like wild fire including pumkin, patty pans tomatoes…. They get sun almost all day and wetering is done by dripfeed so no water gets to the foliage.

Please help
Ingrid Moss Says:
January 13th, 2012 at 6:04 am
Raw butternut can be eaten and is absolutely delicious if grated and mixed with grated pineapple and a small tin of granadilla pulp. Try it!