Growing Winter Squash in the Copper River Valley

Squash caterpillar tunnel. Photo by Tenley Nelson.

Tenley Nelson - Wood Frog Farm

I have successfully grown winter squash in Strelna along the McCarthy Road for many, many years now. But I have also had seasons when I only got two or three fruits even with my best efforts. 

When I was working as a teenager on a commercial farm in New Hampshire, we had acres and acres of squash that were left unattended once the vines shaded out the leaves and produced pallets upon pallets of pumpkins. It is not like that here.

The squash is babied from seed to harvest so be prepared to pay daily attention from May through September. It is never a guaranteed crop but overall my yields have steadily improved. I never sell winter squash as they are too time consuming and nutrient needy in general to be a cost-effective crop, but on high yield years, I will share my extra with friends. It always makes me feel like I am uber wealthy to be able to share the colorful and delicious fall fruits.

My favorite part of growing winter squash (other than eating it of course) is the tactile experience of holding a dense, warty, or ribbed squash. The flesh is cool to the touch and the weight is always heavier than expected. I love the feeling of running my fingertips over the different textures and shapes. Deep ribs on the acorns, teardrop handfuls for the Kuris, spaghetti squash smooth dragon eggs, tiny warty bumps dotting the surface of the pie pumpkins. It is a good idea to handle your squash, and often, as that is how to spot any signs of soft spots or spoilage. This way you can use it up before it rots in place.

Acorn squash. Photo by Tenley Nelson.

We have so many microclimates in the Copper Valley that my technique will not work for everyone but here is how I do it.

My garden is at 1200 feet above sea level, on a gentle slope, and almost exactly in the middle of the Chitina River Valley between Iron Mountain to the north and the Chugach Mountains to the south. We are located at one of the lowest snow areas in the Chitina River Valley as the snow level increases the closer you get to the mountains. The hottest and driest part of my garden is the top four beds and that is where I plant all my heat loving crops.

I have tried many techniques over the years. What is currently consistently working the best is 50-foot long beds that are three feet wide with two-foot wide paths in between. The beds are freeform and slightly raised as I only walk in the pathways which have become compressed over the years. They are also slightly terraced due to the slope.

I use thick landscape fabric that I have carefully heat punched three inch diameter planting holes in for the spring starts. Two feet between summer squash and three feet between winter squash down the center of the bed. While I do not like using plastic in my garden, I have found this to be the only way to both increase the soil temperature and suppress the extremely vigorous horsetail that naturally carpets the forest floor in my area.

Spaghetti squash. Photo by Tenley Nelson.

I try to purchase seeds that are bush or semi bush in growth habit. Bush plants will not vine at all. Semi-bush will send out short vines which are easier to manage. Standard winter squash will sprawl in all directions. I do grow these, but I am obligated to manage the vines to keep them inside the tunnel as the season progresses. It is easier to grow the bush varieties inside a low tunnel. 

I also do not buy varieties that take longer than 90-95 days to mature. Due to our cooler weather, the so-called 90-day squash will often take far longer to mature. 

Squash love to be dry and hot. That is our big challenge as Copper Valley gardeners because while June and July can often provide a good amount of warmth for the growing plants, August is most often cool and rainy when the fruits need heat to finish developing. Once fertilized the fruits needed about 55 warm days to mature. It will take much longer in cooler weather and sometimes they will just rot in the cold wet weather instead of finishing up.

Over the landscape fabric, I have ten-foot long electric metallic tube (EMT) conduit (purchased from Home Depot or Lowes) that I have bent into four-foot diameter hoops. The hoops are placed into the soil in a row every five feet. I use twine to make a purlin on the top, cover with a 10’ by 50’ piece of plastic, and secure every other hoop using a crisscross of twine tied to survey stakes. I tighten the twine using a taut line hitch. 

Tote of harvested squash. Photo by Tenley Nelson.

This “caterpillar” low tunnel is a very affordable way to grow warm weather crops here. I open them every morning and close them every evening to maintain the best temperatures possible. If you have a high tunnel, great! You will not experience the space constraints and humidity issues that low tunnel users struggle with.

I start my winter squash seeds in a heated greenhouse in three inch pots three weeks before June 1. If it is a late spring, I will delay this. You do not want to plant your starts after three weeks EVER! No exceptions. The older the starts get, the more transplant shock and growth delay they will experience.

Use the utmost care when you do plant out your starts to prevent transplant shock. Have them well watered with a weak kelp infusion (made by soaking Maxi crop or Down to Earth kelp powder in water for several hours) the day before you plan on planting them out. This will reduce transplant shock and provide micronutrients. Put more kelp infusion in the transplant hole and gently firm into place disturbing the roots as little as possible. 

I plant in the afternoon if it is a very sunny day so that the starts have an entire night to get settled in before being blasted with the intense June sun.

The beds have been prepped with farm made compost over the (now dead) cover crops that were grown in place the year before. My garden is twice as big as needed as I grow cover crops on one side and veg on the other. I switch each year so that the soil is always being replenished. Occasionally I will add a small amount of Down to Earth organic slow-release fertilizer, bio live or all-purpose, but with cover cropping and compost, commercial fertilizer is usually an unneeded expense.

Squash plants have male and female blossoms. The female one has a miniature undeveloped squash at the base. The last several years I have struggled to produce male flowers in the beginning of the season. As the goal is to get the fruits developing as soon as possible, there is nothing sadder in June than having female blossoms and no way to fertilize them. 

Immature buttercup squash. Photo by Tenley Nelson.

In the future, I plan to start a zucchini plant in the greenhouse in a pot earlier than the outside ones to ensure this does not happen to me again! Any male squash flower will pollinate any female squash blossom. Unless you are saving seeds for open pollinated varieties, there is no need to worry which plant it comes from.

Once I have both male and female flowers producing, I check the plants daily and pick the male flowers and fertilize the females by spreading the pollen from the male flower into the female flower. I remove any faded male flowers or unsuccessfully pollinated females from the plants and put them on the compost pile. Left on the plant, they will eventually rot in place and create a moldy mess that can compromise developing fruit.

At the end of July, there is no longer enough time to develop a mature winter squash. The varieties I grow need 50 to 55 warm days which August and September will not provide. At this point I still check every day and remove all the new blossoms and check on the developing fruit. You can nestle some dry straw under each one to help protect the fruits from developing a bottom rot spot in a wet and cold August.

Mature winter squash can handle a light frost, but it is always better to pick before it goes below 32°. The squash is ready to pick when the skin is not easily pierced with a fingernail and the tendril curl nearest the stem is dried up. I cure mine in my windowsill because it is never warm, dry, and sunny enough to dry outside. I leave them there for several weeks and pick them up often to check for soft spots. If I find one, I carve it out and cook the rest of the squash right away. We make baked squash, squash curry soup, add raw chunks to soup or stew, and pies. I think kabocha and buttercup squash make better pumpkin pie than pie pumpkins.

Here are some varieties I have had success with:

Red Kuri (not a bush variety)

Blue Kuri (not a bush variety)

Black Forest Kabocha (semi bush)

Baby Blue Hubbard (not a bush variety)

Long Pie Pumpkin (not a bush variety)

New England Pie Pumpkin (not a bush variety)

Sweet Reba Acorn (bush)

Pinnacle Spaghetti (rated as bush but sprawling. Incredible yields)

Bon Bon Buttercup (not a bush variety. My current favorite for flavor.)

Delicata (there are bush and non-bush varietals)

I have grown many other types and have had many failures, but it is always worth trying. It might make it in your microclimate. I have also grown squash that produced beautifully but I did not like. (Kindred Orange Buttercup from Turtle Tree Seeds is one example. So many small, beautiful squash but I didn’t enjoy the taste.)

Let me know what has worked for you in your garden or greenhouse and what varieties are your favorite. I can be reached through the paper. We are coming up on “plan next year’s garden season” and hopefully this helps you with your squash growing goals.

From my garden to yours, happy planning!

This article was originally published on November 2.