Growing Organic Pumpkins

If you use floating row covers, you can transplant pumpkins to your garden a couple weeks before the last anticipated frost. Growing organic pumpkins is simple… learn how in this post.

Pumpkin Facts

If you’re growing pumpkins, you’ll pretty much be following the same guidelines as you’d follow for winter squash.

The most ancient evidence of growing pumpkins dates back to around 7000 B.C. in Mexico.

Farmers in the U.S. are currently growing pumpkins at around 1.5 billion pounds per year; gardeners add many more to that.

One of the favorite usages of pumpkins is for the Halloween “holiday” when much of the populace carves goofy faces in their pumpkins and put candles in them. If you really want to know why, Google it.

When to Plant Pumpkins

You’ll need about 80 to 120 frost free days when growing pumpkins to allow them to mature.

You can begin growing your pumpkins indoors about 4 weeks before your last frost date. The soil should be about 60° to 65°F at 2 inches depth.

If you use floating row covers, you can transplant pumpkins to your garden a couple weeks before the last anticipated frost.

If you live in warmer areas you can plant your pumpkin seeds directly after the danger of frost is past, typically around the end of March or mid-April.

You’ll want to plan to have your pumpkins mature by late summer or early fall. The larger the pumpkin, the more days they take to mature.

Where to Plant Pumpkins

Pumpkins require at the very least 6 hours of full sunlight daily.

Growing pumpkins require garden soil that drains well and has plenty of organic materials blended into it.

Your soil ideally should have a pH balance in the range of 5.8 to 7.5; right in the middle of that is the best pH level.

Your soil needs sufficient levels of nitrogen, phosphorus, and potassium, most of which are achieved with the liberal application of compost and/or composted manure, bone meal, blood meal, and the like.

Preparing Your Soil to Plant Pumpkins

Pumpkins need copious amounts of soil nutrients which can be supplied mainly with compost and composted-manure.

The best way to apply your compost is to lay out where your hills will be and mix several inches of compost into about a 2 foot diameter area about a foot deep.

If you’re rototilling rows, add 2 to 4 inches of compost, composted manure, etc., and rototill it to around 8 inches deep.

You can also mound the soil where your plants will be to aid in the mixing in of compost or other organic matter.

Other items you can add to your soil are alfalfa meal early in the season for nitrogen, and feather meal later in the season, ground oyster or egg shells for calcium, greensand for potassium, and kelp meal for trace nutrients.

Choosing The Right Seed Varieties for Your Area

If you have a small garden, it’s good to note that pumpkin vines can occupy up to 100 square feet.

Pumpkins, at least most varieties, are too heavy to trellis, but do grow well in larger garden areas.

Contact your county extension office to find out if there are common diseases in pumpkins in your area. If there are, get recommendations for seed varieties that are resistant to those diseases.

Diseases that afflict pumpkins are covered in detail in the latter part of this post.

Seeds and Germination

Pumpkin seeds are usually still plantable 6 years after you’ve purchased them from a reputable seed supplier.

Pumpkin seeds won’t germinate in soil temperatures lower than 60°F or higher than 105°F. The optimum germination temp is between 86°F to 95°F.

The seedlings should emerge in about 5 days at the optimum temperature range if they are in full sunlight or under grow lights (fluorescent lights are OK).

If you’re seeding directly to your soil, you can use a black plastic mulch to heat up your soil. Secure your plastic with soil (make sure all edges are covered with dirt), and cut holes for seeds.

Your garden soil temperature shouldn’t be no lower than 60°F to 65°F to germinate your pumpkin seeds.

Starting Pumpkin Plants Indoors

Plant your pumpkin seeds in peat pots or soil blocks 3 or 4 weeks before the last frost. You can use tapered plastic pots as well, but peat pots and/or soil blocks are better options.

Use a good potting mix or starter mix to start your pumpkin seeds in. These mixes are readily available at your local garden center.

If you want to create your own potting soil mix, you can purchase mixing loam soil, sphagnum peat moss, and perlite at your local garden store. Adding compost to this mix will create an optimal starter mix.

Don’t use garden soil as it has lots of weed seed, fungus spores, and bugs in it that aren’t optimal for starting your pumpkins indoors.

If you want to grow a pumpkin plant or more in containers, you’ll need to get at least a 10 gallon pot.

Mix 9 gallons of potting mix, a couple cups of alfalfa meal, half a cup of feathermeal, half a cup of powdered eggshells or oyster shells for calcium, half a cup of greensand for potassium, and a few tablespoons of kelp to cover your trace minerals.

Plant three or four seeds about 1″ deep. Don’t thin until the plants have at least 2 true leaves; leave the 2 best seedlings and after one is about 10 inches tall, choose the best plant and clip the other off with a scissor.

Transplanting Pumpkins to Your Garden

Before you actually transplant your pumpkins to your garden, you’ll need to “harden off” your plants.

To harden off your pumpkin seedlings, move them outside during the daytime and cut back on watering.

Your plants should have 2 or more true leaves at this stage and it will have been 3 to 4 weeks since you originally planted them.

As pumpkins prefer warm temperatures, ideally the daytime temps will reach 75° to 85°F daytime and 60° to 65°F nighttime temperatures.

However, if you live as far North as we do, you may not hit those temperatures until 2-4 weeks after transplanting, so it might be advisable to use row covers and black plastic ground cover to help your pumpkins to get a good start.

You need a minimum soil temp of 60°F to plant your squash, so plant them in an area that gets lots of sun.

If you’re planting in rows, space the rows 4 to 6 feet apart and the plants about 2 to 3 feet apart in the rows. If you have a larger variety of pumpkin, you might want to plant them 3 to 4 feet apart in the rows.

When you plant your pumpkin seedlings, dig a hole large enough to place the peat pot, soil block, or soil mass into; then pack soil in around the plant.

Make sure the soil is moist but not too wet; you shouldn’t be able to pack a tight dirt clump with your hand or it’s too wet.

Plastic mulch, set down a couple of weeks prior to your anticipated transplant date, is a definite help (how much of a help depends in good part on what kind of plastic mulch you use–the traditional black is the least helpful).

Planting Pumpkin Seeds Directly to Your Garden

Once your soil temps have stabilized above 60°F, you can plant pumpkin seeds in your garden. You should make sure that you’re past the danger of frost.

If you’re hilling your pumpkin area, make your mounds about 4 to 8 feet apart and plant 4 to 6 seeds about one inch deep and about 1 inch apart in a circle or square configuration.

If you’re planting in rows, the rows should be 4 to 8 feet apart, and the seeds should be planted 6 to 12 inches apart.

Once the seeds have germinated, you can thin your plants to one every 18 to 36 inches, depending on whether they’re larger or smaller pumpkin varieties, and what your garden soil can handle.

Getting the Most Out of Your Pumpkins

Once your plants have at least 2 true leaves, thin them to 2 or 3 plants per hill, or 18 to 36 inches apart if they’re in rows.

Pumpkins have male and female flowers. Male flower will appear first, 40 to 50 days after germination. A week later female flowers will begin to emerge.

If you have plenty of insects, pollination should be no problem.

If you have too few insects, you’ll see the female flowers begin to drop. To avoid this, you can hand pollinate by using a cotton swab or a small brush to take pollen from the male flowers and dispense it to the female flowers.

Early in the season, make sure the pumpkin plants aren’t choked out by weeds.

Hand pull any weeds within six inches of the pumpkin plants, the surface hoe the weeds that are further away, and rototill weeds more than a foot away from your squash plants.

Once the vines have covered the ground, you’ll not need to weed much in your pumpkin patch the rest of the season.

It’s a good practice, about half-way through the season, to side dress your pumpkin plants (about 6 inches from the base of the plant) with compost, composted manure, or alfalfa meal.

Pruning smaller pumpkins from your plants will help the remaining pumpkins to get bigger.

It’s also a good idea, if you have squash borers in your area, to mound dirt around the base of your plants to discourage them from laying eggs.

Jenny’s Tip – If you’re growing smaller pumpkins (the size of a volleyball or smaller), you can trellis them and as the pumpkins grow, you can use pantyhose or similar to make a sling to hold them up.

Mulching & Weeding

Early in the season, black plastic may be your best mulching option as it warms the soil and suppresses weeds.

Grass clippings or Straw, spread around your pumpkin plants, both help to throttle pesky weeds and conserve soil moisture.

You won’t want to apply these types of mulches until the soils reach about 75°F as mulch tends to keep your soil cooler.

One of the biggest assets of mulching is that because pumpkins have shallow roots systems, you won’t have to disturb them much by weeding.

Watering Pumpkins

When growing pumpkins, depending on your climate, they should be watered between 1 and 2 inches weekly.

If you mulch, you can use somewhat less water, but still check your soil’s moisture level frequently during hot, dry spells.

If you water once per week, especially if you’ve mulched, that should be adequate.

Water enough to get about 6 to 8 inches into your soil. Light watering of pumpkins is virtually useless.

If your soil is sandy, use a smaller amount of water, but water a couple of times per week.

If your pumpkins are trellised, you may need to water a bit more than if the plants are rambling across the ground.

As with most vegetables, drip irrigation or soaker hoses are the preferred watering method. However, if you only have overhead sprinklers, water early in the day so as to reduce risk of fungi and mildews.

Companion Planting and Rotation Considerations

Good companions for growing pumpkins include:

Beans which supplement your garden with nitrogen that it absorbs from the air.

Pumpkins help corn roots retain moisture.

Radishes are reputed to protect your pumpkins from squash borers.

Mint is said to help control ants, aphids, flea beetles, and rodents.

Onions ward off fruit tree borers, weevils, aphids, rust flies, moles, and some root nematodes.

Marigolds and Nasturtiums repel bugs and beetles away from your squashes. They also attract bees which help to pollinate your squash flowers.

Oregano is also said to benefit squash in keeping away many pests.

Bad Companions for winter squash are potatoes. Potatoes inhibit the growth in squash plants.

You don’t necessarily need to rotate squash annually unless you’re having issues with verticillium wilt, fusarium rot, or mosaic virus.

When to Harvest Pumpkins

Like most winter squash, pumpkins are ready to harvest when the skin is hard and you can’t puncture it with your fingernail.

We usually wait until the first “killing frost” to harvest our pumpkins. By this time the skins are usually a dark orange and the stems have hardened.

I always use a pruning shear to cut the pumpkin stem from the vine, leaving around 3 inches of stem. This helps protect the pumpkins from rotting and provides a handle for picking it up.

It’s a wise practice to wear some type of cloth or leather glove when handling pumpkins as the dried stems are quite abrasive.

Handle your harvested pumpkins with care. Bruising or injuring the skin will affect the storability of pumpkins.

Storing and/or Preserving Pumpkins

Pumpkins store well through the winter. We’ve often still had pumpkins into June if they’ve been harvested with care.

A basement area, dark space in your garage, a crawl space under your home, or a root cellar are typically ideal locations for pumpkin storage.

If a pumpkin has been bruised or cut during harvest or when moving into the storage area, use these first as they’ll rot more quickly in storage.

You can cut out the rot spots and bake, steam, or otherwise cook pumpkins with no negative effects to the flavor or nutrition of the remaining portions.

You can steam and freeze pumpkins as well as can pumpkin if you don’t have an appropriate storage location.

Beware: it may be difficult to get the pumpkin hot enough to kill all the bacteria that is recommended if canning a puree, so it may be best to cube the squash and can it in a little sea salt and water.

We have experimented with pumpkins and kept it in warmer areas of our home at 65° to 70°F through the winter and still had plenty of pumpkin to eat all winter.

Preventative and Natural Solutions to Common Pests

Cucumber Beetles are a striped beetle that is about 3/16″ in length, greenish yellow, with three black stripes running down it’s back.

The spotted cucumber beetles is pretty much the same but with a dozen spots on it’s back.

Regardless of what these beetles look like, they’re pretty nasty pests that eat your plants and spread bacterial or verticillium wilt to your plants.

To prevent these beetles from getting to your plants, you can use row covers before flowering to keep them away from your pumpkin plants.

If the problems get too serious, you can use organic pyrethrins or organic rotenone to deal with these critters.

Another nasty pest is the squash vine borers. They typically appear about the time the vines begin to spread out across your garden. Fortunately, they don’t attack butternut squash, cucumbers, watermelons, or muskmelons (cantaloupe).

Squash vine borers are an inch long or so, quite fat, and are white with a brown head.

They are the larvae of a small moth with dark front wings and light rear wings and a red abdomen. The moths lay eggs in the late spring or early summer near the base of your pumpkin vines.

The borers appear about a week later and drill a hole in your vine to get inside them. You’ll see a small hole and green excretions below the hole. And you’ll see the vine die rather suddenly.

To prevent squash vine borers from decimating your crops, first, watch for the moths (and listen…they have a buzz when they fly that’s unusual for moths).

You can also use yellow-colored bowls filled with water to trap these moths; they’re attracted to the color, so will fly into the bowls and drown.

At this point, it’s a good idea to use row covers for about 2 weeks until the moths disappear again. Make sure you cover the edges of the row covers with dirt to seal out the moths.

If your plants begin flowering during this time, you can hand pollinate your pumpkins if necessary. Don’t use insecticides as they can also kill beneficial insects that pollinate your crops.

If you discover the borer has created a hole before the plant wilts and dies, you can sometimes carefully cut a hole in the vine and remove the borer. Cover the vine and the hole with dirt; much of the time it will send roots into the soil from the cut area.

If you find a vine that’s been killed by a borer, cut back the vine and destroy it.

Aphids are also common pests that can be found on the undersides of your pumpkin leaves. You’ll know they’re there if you see leaves turning yellow and crinkling or curling.

Aphids suck the juice from your plant leaves and leave a sticky substance behind. The only beneficiary of this process is ants, who harvest the sticky sweet stuff.

The best solution to aphids is to import ladybugs to your garden. They feed on aphids and are very effective in ridding your plants of these little green bugs.

Another solution is to “wash” them off with a hose and high-pressure spray nozzle or an organic insecticidal soap.

Squash Bugs are probably the most prevalent pest but are somewhat easier to control than borers. They suck the sap from your pumpkin plant leaves, leaving them initially speckled; then the leaves wither and die.

Controlling squash bugs is easier if your soil has lots of nutrients and your plants are healthy.

Get rid of anything around your garden, such as old boards or anything they can hide under during the winter.

It also helps to rototill or turn under your garden in the fall to eliminate places these bugs like to hide in.

To get rid of the bugs, hand-picking usually works in a garden as it’s not so large as to take more than an hour or two per week for a few weeks in the summer.

When you pick these bugs and nymphs, have a pail of soapy water to drop them into…the soap breaks the capillary action of water so the bugs immediately sink and drown in the water.

If you find eggs attached to the underside of leaves or stems, simply crush the eggs.

Lay a board or two in your pumpkin patch overnight…the bugs will congregate under the boards at night. In the morning, lift the board and capture the bugs and drop them into the soapy water pail.

Organic compounds such as rotenone and pyrethrins are also effective if you have a heavy infestation of these varmints.

Environmental Factors

Blossom-end rot causes your fruit to develop a black rot on the end of the squash. Hot weather/lack of water, and a calcium deficiency, are the main cause of the rot. It can be prevented by making sure your plants have water and if necessary, add lime to the soil before watering.

Downy mildew is a leaf disease and is caused by a fungus with a long Latin name. If you really want to know the name, let me know and I’ll copy and paste it in a reply.

This mildew usually isn’t a problem unless you have a cold spell in the 45° to 55°F range for a month or longer.

The mildew shows up initially as yellow patches on your squash plant’s leaves, and then turns brown or tan with gray or white downy fuzz below it. Then it progresses to black patches and the leaves and sometimes the plants shrivel up and die.

To prevent downy mildew, grow squash varieties that are resistant to it.

Also, allow space between your plants so they don’t stay wet too long.

And if the conditions appear favorable for the disease to appear (i.e. a long cool and rainy spell), spray your leaves with a compost tea. To make the tea, put compost in a bucket and fill it with water; when it settles out, fill your sprayer with the brownish water and spray your plants leaves with it.

Powdery mildew is another mildew that can affect your winter squash plants, but looks entirely different. It’s whitish and powdery and grows on squash leaves and stems.

It is also caused by wetness, but warmth and humidity rather than cool weather and rain.

If the leaves are infected, they’ll usually die. If the infections is severe, it can kill the whole plant.

If you are able to, avoid overhead watering. If not, water early in the morning so the plants can dry out by noon or so.

If you keep insect pests under control and spray your vines and leaves with a compost tea solution or a baking soda solution, you most likely won’t have an issue with this disease.

Other solutions include organic sulphur sprays or a weak solution of milk and water (9:1).

If you spot any of this mildew, destroy your vines at the end of the season and rotate your winter squash to a new area next gardening season.

You can also purchase seed varieties that are resistant to fungi such as downy and powdery mildews.

Another fungus with a long Latin name causes a blight called “black rot.” Black rot is found mostly in warmer and more humid climates such as the Southeastern U.S., but can also show up in winter squash and pumpkins in the cooler climates.

Black rot is a gummy blight that attacks the stems and leaves of squash plants. It is usually brought on by too much moisture.

Black rot will survive on dry plant matter or in the soil. It will live there for over a year.

It lives on dry plant material or in the soil, where it can survive for more than a year. It is necessary to rotate your squash crops to a new area if this blight hits your plants.

To avoid black rot, irrigation should be managed to minimize free moisture on leaf surfaces, and a minimum two-year rotation cycle is a must.

Again, overhead watering should be avoided, but if you have no choice, water early in the day.

You can also make an organic fungicide spray using bicarbonate of soda (baking soda). In a gallon of water add a couple drops of organic olive oil, a couple drops of environmentally-friendly liquid soap, and 3 tablespoons of baking soda. Spray it on your squash leaves to effectively control all of the above fungi.

Fusarium fruit rot is a soil-borne fungus that can afflict your pumpkin crop.

You can see this problem in slightly sunken lesions with purplish-red margins. A white fungal growth will develop often in the center of the lesions. It can spread with watering.

Crop rotation and planting resistant varieties are the best defense against fusarium fruit rot.

Straw mulch can help reduce fruit rot by preventing pumpkins from contacting the soil directly.

Don’t store pumpkins showing the described symptoms as they’ll rot quickly in storage.

Angular leaf spot is a bacterial infections that creates spots that have a water-logged appearance and are guided by the leaf veins, giving them an angular appearance.

Warm, wet weather is a promoter of this infection, and if things dry out, the holes created by this disease may be outgrown.

Prevention of ALS starts with clean seeds and resistant varieties. Also, don’t crowd your plants as moisture creates the condition in which this disease thrives.

If you have only overhead watering, do it in the morning. Spray your plants with the homemade fungicide mentioned above if symptoms appear.

Just when you thought it was safe to grow pumpkins, along comes the mosaic virus.

Mosaic is spread by aphids mostly. Your pumpkins leaves will develop irregularly, both in shape and size, and the fruit may have the same symptoms.

Preventing aphids from infecting your plants with row covers may be the best option. Diatomaceous Earth also works well, but only if it remains powdery (not wet).

You might think by this point we’d have nothing else, absolutely nothing else that could affect your pumpkin crop, but unfortunately we still need to mention bacterial wilt.

Bacterial wilt goes back to your cucumber beetles; if they’re around when your pumpkin seedlings emerge, they may infect your plants early.

Bacterial will appears when the leaves start to wilt into an umbrella-shaped appearance, then the whole plant collapses and dies.

As you might imagine, controlling the cucumber beetles will control bacterial wilt, so if your growing your pumpkins organically, row covers are the most effective prevention early in the season.

Most fungal infections can be controlled by planting resistant varieties, rotating your crops, and using the homemade spray mentioned earlier.

Everything else can usually be handled by controlling the bugs with row covers, diatomaceous earth, and pyrethrins if it gets serious.

Th Author:

Barry Brown is a 3rd generation organic gardeners who is passionate about a sustainable and natural lifestyle.

Photo. Susanne Jutzeler