Harvesting and Storing Winter Squash

Sweet Meat winter squash, a Maxima type.
Photo Southern Exposure Seed Exchange

There are four main types of winter squash, and some hybrid crosses. Refer back to your catalogs or websites if you are unsure which type your varieties belong to, as this helps determine when to harvest. If you haven;t grown any winter squash this year, use these photos and descriptions to help you plan for next year. Most of our photos are from Southern Exposure Seed Exchange. We tend to get caught up in the excitement of harvest, and forget to take photos!

Leave the squash on the vine until fully mature. Once the vine is dead, the squash can’t get bigger, but can ripen, change color and convert starches to sugars, (tasting better). In general, squash are fully mature and storable when the skin cannot be pierced by fingernails, but testing each one would leave ugly scars and reduce shelf life, so learn the other signs of ripeness. Yield could be 3¼ lbs per row foot (about 5 kg per meter.)

Not all the squash on one plant will be ripe at the same time, but they come to no harm sitting in the field (provided there is neither frost nor groundhogs). We harvest once a week, using pruners. We cut them with fairly long stems, which helps them store best. Those who need to pack squash in crates remove the stems so that they do not injure their neighboring squash. If you do this, you need to cure the open ends before crating. Handle squash as if they were eggs, not footballs. Bruising leads to rot in storage. Look for black rot infestations (concentric circles on butternut) and either compost those, or salvage the good parts for immediate use.

Pepo Squashes are ready soonest

Candystick Dessert Delicata winter squash. These are Pepo types.
Photo Southern Exposure Seed Exchange

The first squash ready to harvest (in early September) are the Pepo “winter” squash species (more properly called fall squash), including acorn squash, delicata, dumplings, spaghetti squash, and most orange pumpkins. If you want to start harvesting these in August next year, sow earlier than late May! Pepo squash are fast maturing, short-storing, mild flavored. They have prickly leaves and stems. They are susceptible to vine borers, and perhaps a little more susceptible to viruses than other types. Pepos have hard, five sided stems, and the fruits are often ribbed.

When they are ripe, the “ground-spot” of Pepos usually becomes the color of pumpkin pie filling after the cinnamon is stirred in, or else bright orange. The stem will still be bright green. Wait till at least 45 days after pollination. Harvesting too early will disappoint: the squash will be watery and fibrous, without sweetness. Pepos can store up to 4 months, so check them every week and eat them up before New Year.

Maxima Squash

Maxima squash plants have huge hairy leaves. Fruits have thick round stems, different from the angular stems of the other species. This group includes buttercups/kabochas, hubbards, bananas, the Big Max giant pumpkin, Jarrahdale, Candy Roaster, Galeux d’Eysines and Rouge Vif d’Etampes. They are very susceptible to wilts, borers and squash bug damage. We have found Jarrahdale to have relatively high resistance to squash bugs compared to other Maximas. The hybrid Kabocha, Cha-Cha, is reliable. Kabocha may be harvested slightly under-ripe, as they continue to mature after harvest.

North Georgia Candy Roaster winter squash, a tasty Maxima variety. Photo Southern Exposure Seed Exchange

Maxima squash are ripe when at least 75% of the stem looks dry and corky (tan, pocked, wrinkled). They have fine-textured good-flavored flesh They will store 3-5 months, sometimes longer.

The weakness of maxima compared to the others is susceptibility to downy mildew. There may be other fungal pathogens that maxima is more susceptible to.

In central Virginia, maximas are almost always a loss, due to squash vine borers. Ken Bezilla at Southern Exposure Seed Exchange has watched the plants live for about 70-80 days, the fruits get nice and big and then the plants die all of a sudden. The safest way to grow them is under rowcover or netting, and keep them covered for the first 60 days (briefly uncovering for weeding and pollination).

Moschata squash

South Anna Butternut winter squash, a Moschata bred by Edmund Frost to resist Downy Mildew. Photo Southern Exposure Seed Exchange

Moschata squash plants have large hairy leaves, and fruits have flared angular stems. This species is the most trouble-free, with no damage from borers and cucumber beetles. The tougher stems repel invaders. They need warm growing temperatures above 60°F (16°C). Butternuts and similar tan-colored squash, such as Seminole, Cheese, and the large Tahitian Butternut and Lunga di Napoli are in this group.

Mrs Amerson’s Winter Squash, a large and beautiful Moschata.
Photo by Southern Exposure Seed Exchange

The Moschata species usually have bright orange, sweet, tasty flesh. These squash are ready when the skin is an even tan peanut-butter color, with no pale streaks or blotches. Many have green lines radiating down the squash from the edges of the stem. In some varieties, these green lines disappear when the squash is ripe, but not in all kinds. If in doubt, cook one and see. Or try a slice raw. These squash also have angular stems, but unlike the stems of pepo squashes, moschata stems flare out where they join the fruit. Moschatas can store 4-8 months or even longer. Seminole is a Moschata that will keep on the shelf for a whole year after harvest. It has a hard shell!

Mixta (Agyrosperma) Squash

Green Striped Cushaw Winter Squash, a Mixta variety, also known as Striped Crookneck.
Photo Southern Exposure Seed Exchange

The fourth species, Argyrosperma, or Mixta, includes many old-time varieties from the south. Flesh is often yellow rather than orange, and these squash are often cooked with sweeteners. Plants are rampant; leaves are large and hairy. Fruit stems are slightly flared, slightly angular, and hairy. This group has the best drought-resistance and also good resistance to borers and beetles. Cushaws are Mixta species. They are not all great storers.

Curing and Storing

Butternut and buttercup squash need to be cured at 80-85°F (27-29°C) for 7-10 days to be sweet tasting. Other varieties do not need to be cured, unless the stems have been removed, You can cure squash in a greenhouse with 80% shadecloth, or simply in a warm storage room.

Curing conditions for winter squash can be quite far from the ideals. Many people simply put the squash straight into storage Just don’t eat uncured butternut or buttercup squash, ie within two weeks of harvest, to avoid disappointment.

Our winter squash storage cage. Photo Twin Oaks Community

Store winter squash in relatively warm and dry conditions: 50-60°F (10-15°C) and 50-75% humidity. Check through stored squash once a week, removing any that are rotting. Squash have a medium demand for ventilation, similar to carrots, more than potatoes. Temperatures below 50°F (10°C) can cause chilling injury, which reduces shelf life. Do not store squash with potatoes or onions; like most ripe fruit crops, squash exhales ethylene, which increases sprouting in potatoes and onions (and other roots and bulbs).

More Information:

Roxbury Harvest Manual 2012

ATTRA Organic Pumpkin and Winter Squash Marketing and Production

How to Read Seed Catalogs

2013-catalog-cover-DROPThis is a long post, but if your weather is set for all-day drizzle like it is here, you’ll have time to read it. I’m also sending a much shorter version to Mother Earth News, where I’m joining their Blog Squad. So if you are very short of time, you can look there in a few weeks.

This season is becoming past-tense, and some of us are already starting to think about next year. Seed companies are putting their catalogs together, and soon we’ll be snuggled beside our woodstoves perusing them, hoping to find varieties that will not repeat this year’s problems. Reading between the lines of the variety descriptions is a science and an art. How not to get carried away by all the positive exclamations and miss some basic fact that would tell you this variety is not for your farm?

Which catalogs do you buy from? See the Safe Seed Pledge list for companies that do not knowingly buy, sell or trade genetically engineered seeds or plants. You may want to buy from local small seed companies who specialize in locally adapted varieties. Crops that overwinter in zone 7 could die in zone 5.

 “Adaptable” “easy to grow” are good phrases to look for. Naturally, your climate will affect what grows well. Here it’s too hot for us to grow runner beans, Brussels sprouts, or cauliflower. We don’t buy our okra seed from companies in the north – they are focused on varieties which will produce a decent crop in their climates. Our worries are different. “Requires an attentive grower” is a helpful warning. The size and skill of your labor force matter. Can you pick beans quickly enough to earn a decent living? “Best for organic production” means it doesn’t require lots of pesticides to keep it producing.

Heirlooms, OPs or hybrids?

9781596912915What does your market want? Are they truly committed to heirlooms, or is flavor actually more important? Those are not the same thing! Some old varieties are rare for a reason! People didn’t like them much! Others are fantastic and easy to grow in quantity. Finding which are which is difficult. Heirloom tomatoes are a special challenge: which ones crack and split?  The Heirloom Tomato: From Garden to Table: Recipes, Portraits, and History of the World’s Most Beautiful Fruit by Amy Goldman is not just a beautiful book, but a very useful one. The author spills the beans on which varieties are worth growing. She has books on squash and melons too, but I haven’t had the joy of reading those yet. Another reliable source on tomatoes is Craig LeHoullier.

Comparing varieties

An early zucchini might be 47 days from direct sowing, but even the late Costata Romanesco is only 52 days. How important is it to have zucchini 5 days earlier? And after your first sowing, is it still as important to have a 47-day variety? Or could you choose a different one (with other good qualities) and simply sow it a day or two sooner?

Raven zucchini has no listed disease-resistance, while Dunja withstands Powdery Mildew, Papaya Ringspot Virus (I had no idea. . .), Watermelon Mosaic Virus and Zucchini Mosaic Virus. Dunja has high yields of dark green zucchini, and so does Raven. Dunja has open plants and only small spines, so harvest is easy. Raven has open plants too. No mention of spines – are they wicked? Dunja is organically grown, Raven is not. How about price? Dunja costs twice as much as Raven! What price organic seed, disease-resistance and short spines?

Tender Grey Zucchini from Southern Exposure Seed Exchange
Tender Grey Zucchini from Southern Exposure Seed Exchange

Spineless Perfection (45 days) and Tigress (50 days) offer the same disease-resistance package. Both are medium green, high yielding, cylindrical zucchini. Spineless Perfection has an open plant, Tigress is only semi-open, and makes no promises about lack of spines. Price is very similar. Risk the five-day delay, the spines and the only “semi-easy harvesting” to save a dollar on 1000 seeds?

Disease resistance and tolerance

Good catalogs have a wealth of information about disease resistance or tolerance of their varieties. Do read their list of codes or abbreviations. (Admittedly the lists can sometimes be hard to find.) Don’t be a vegetable hypochondriac! Don’t let the length of the list scare you off – your plants won’t get everything listed. Johnny’s had 66 items in their Vegetable Disease Code list last time I counted.

It really helps if you monitored your plants and know which diseases you are trying to avoid. We don’t worry about Pea Leaf Roll Virus or Enation Mosaic Virus of peas because our pea season is so short that the plants will be dead of heat stroke before they get sick with anything.

Septoria Leaf Spot of tomato. Photo University of Minnesota Extension Service
Septoria Leaf Spot of tomato. Photo University of Minnesota Extension Service

When I was new to Virginia it took me several years to realize our tomato leaf disease was Septoria Leaf Spot. I even bought Early Blight resistant tomato seed one year and was sorely disappointed at the spotty leaves they got.

Beet greens resistant to cercospora will provide beautiful greens as well as roots. Early Wonder Tall Top is rated by Johnnys as the best beet for greens.

Days to maturity

Johnnys gives days-to-maturity from cool weather spring transplanting. They suggest adding 14 days from direct sowing (direct-sown crops suffer no transplanting shock, so grow faster overall, but you need to add in extra time from seeding to transplant size). Subtract 10-14 days for warm weather transplanting (as crops grow quicker then). Fedco lists days from direct seeding for many crops.They suggest subtracting 20 days from date of transplanting. With warm weather crops they list days from transplanting. For peppers the days listed are from transplanting to full-color maturity. Some catalogs list days to full-size green peppers only. “Early maturing” isn’t so useful if the seed rots in cold soil, so check for both pieces of info. Provider bean is cold-soil tolerant and fast-maturing.

Packet sizes: grams, ounces and seed counts 

Take a steady look at packet size and seed specs (seeds/ounce or seeds/gram). Alas, this country has not yet fully metricated. Seeds are measured out in many ways. Go to www.metric-conversions.org/ and print yourself some conversion tables, or use the online calculators. Take a dark pen to your catalogs and write in the relevant numbers.

Flavor.

For a particular crop is “mild” better than “rich” or “robust”, or not? There are mild-flavored Asian greens such as mizuna, available in green, red and purple, and there are spicy mustard greens that look very similar: Golden Frills, Ruby Streaks, Scarlet Frills, Red Splendor.

Ruby Streaks beside green mizuna.  Credit Ethan Hirsh
Ruby Streaks beside green mizuna.
Credit Ethan Hirsh

Ruby Streaks is an exceptionally beautiful plant. We tend not to like spicy mustard greens, but cut small into a salad mix, we have no trouble enjoying it.

“Compact”, “Mini” = small. Do your customers cook for just themselves? They’ll want mini. Are you supplying institutional kitchens? They’ll usually want full-size crops, unless they like “snack-size cucumbers” which they serve whole, with less work. If you want big cabbages, don’t buy from catalogs which have carefully chosen small to medium-sized heads because that’s what most people want these days. It can be hard to compare weights with measurements. Small = 2-4lbs, 4-6”. “Mini-broccolis” SanteeDe Cicco won’t produce a big head, ever, just florets. Be sure your crew knows what size to pick.

Mache (corn salad) is a very small vegetable, usually eaten when the whole plant is 3-4” across. Even if the variety description says “long leaves” it’s all relative – maybe they’ll be 4” rather than 3” if you let them really grow.

At the other end of the Rampancy Rating are these key phrases: “needs room to roam,” “vigorous vines”: you can’t sell vines! Are they worth the space? Be sure you plant with appropriate spacing. “Needs sturdy trellis”: is it worth the time?

  “Will be bitter in hot weather.” “Prefers warm days and nights – expect reduced yields in cooler areas” – you have been warned! Remember to check this. It’s refreshing that some catalogs now are more upfront “Not heat-tolerant” says Fedco about Bush Blue Lake bean. If your spring heats up quickly, you’ll want greens that are bolt-resistant as well as cold-tolerant, so you can set them out early. Giant Viroflay spinach sure grows big leaves, but they don’t last long in our climate. Tyee is more bolt-resistant, much better for us. Big chicory, radicchio and endive leaves are going to be bitter if grown at the wrong time of year and not blanched. And sometimes even if you do: they are not uniform varieties.

Concentrated Fruit Set” versus “long harvest season”: length of harvest season is best viewed as potential rather than promised. If Mexican bean beetles or downy mildew are likely to take down your crops, you might do better to sow successions more frequently and not worry about long harvest periods. “Uniform maturity” is definitely a plus if you are growing a drying bean, popcorn, edamame or other single harvest crop. “Holds well in the field” is to your advantage if you hope to pick three times a week for a month.

“Easiest for hand harvest” (E-Z Pick beans) means they come off the vine easily; but “better for hand harvest” can mean simply unsuitable for machine harvest (plants sprawl). “Intended to be picked very slender” means tough when big, so be sure you get a high enough price to justify the lower yield and extra harvest time. And be sure you can harvest every 36-48 hours, or you won’t have anything edible.

Some broccoli has “good side-shoot production” (Gypsy, Amadeus, Belstar). If side-shoots aren’t mentioned, it’s likely that variety was bred for crown cuts.

“Short-term storage only” – we usually read this as “not for storage.” Tendersweet is a fine cabbage for fresh use – its leaves are thin and sweet. Thin leaves dry out fast, so it’s not good for storage.

“Retains flavor when frozen or canned”  “Best for sauerkraut” “Good for kimchee” “Easy to shell” These phrases are music to the ears of gardeners putting up produce for winter.

Onions and latitude

A bed of young onions. Credit Kathryn Simmons
A bed of young onions.
Credit Kathryn Simmons


Latitude makes a difference with onions. Happily, more catalogs now state which latitudes each variety is adapted for.  We’re at 38°N. No use us growing Red Bull (43°-65°), as the days never get long enough to initiate bulbing. Nor do we have much hope for Desert Sunrise (30°-36°) – because after the spring equinox, our hours of daylight are more than further south – they will start bulbing before having a chance to grow very big. A few small leaves cannot produce a big bulb.

Pumpkins or squash?

Some vegetables commonly thought of as winter squash are in catalogs as pumpkins. Many cans of pumpkin pie filling are not made from round orange-skinned pumpkins, but from squash. Choose squash varieties that grow well in your area and make all the pies you want. Or make no pies and serve the squash baked, or in soups. There are four types of squash: Pepo, the classic pumpkins, pattypans, acorn squash, delicata, dumplings,  zucchini and summer squash; Moschata, the long-storing usually tan ones with hard five-sided stems, such as butternut, cheese pumpkins and Seminole squash; Maxima, the (often large) ones with fat round corky stems, such as hubbards, buttercups and bananas; and Mixta, less-common older Southern types like Cushaws.

Research at Southern Exposure Seed Exchange this year showed that many Moschata squash varieties, the kind most resistant to bugs, are also tasty at the immature stage as “summer squash”. So ignore what you’re “supposed to do” and do what works!

“Parthenocarpic” plants can set fruit without pollination, so good for hoophouse growing or production under rowcover or insect netting. Some new varieties  of cucumbers and squash are parthenocarpic, and higher-priced, but some old favorites also happen to be parthenocarpic, Little Leaf pickling cucumber, for example.

“Gynoecious” plants have only female flowers, so yield can be higher. These plants still require pollination to set fruit, unless they are also parthenocarpic, so some seeds of another (pollinizer) variety are included in the packet. You’ll need to grow some of these, even though they won’t themselves give you the fruit you want. Sometimes the pollinizer seeds are colored, so you can be sure to sow some.

“Monogerm” beets produce only one seedling from each seedball/fruit. Others will need singling.  Trade-off price versus time singling.

Warring sweet corn types

Don’t plant any Super Sweet varieties unless you put them at least 100ft away from other kinds, or you make sure they don’t flower within 10 days of each other. Mistakes will lead to horrible starchy kernels in both plantings. Think about this also if you are growing popcorn, dent corn, flint corn. Those dry corns also need to be separated from all sweet corns. Ignore the small print on this at your peril.

Super Sweet corns have other challenging features: the seed is smaller than normal corn, so your planter may need adjusting; Super Sweet seed needs to absorb twice as much water to germinate as normal corn; Super Sweets  are more particular about seed depth (they do better at a shallower depth);  Super Sweets have twice as much sugar as other corn and get sweeter after picking. It can get too much, so refrigerate promptly after harvest.

Too good to be true 

New fancy types are often more risky. They don’t have all the problems resolved. Romanesco Broccoli – I don’t know anyone in Virginia who has successfully grown it. Flower Sprouts – hmmm. Try brand new things on a small scale first. All the fanfare over Indigo Rose tomato, the excitingly evil Deadly Nightshade color of the immature fruit, and then – blah flavor when ripe. “Good” flavor in a catalog may be the lowest rating. “Attractive purple pods” – Do they turn green when cooked? Purple carrots, striped green and white eggplant, white beets – will people buy them readily or will it be an uphill struggle? 

Enjoy your winter catalog browsing! Here’s a cheering photo of wonderful fall colors at Twin Oaks. This is from Ezra’s blog A Year In the Woods

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