Category Archives: 6. Seed Cleaning

Saving Purslane Seed

In the last 3 years, Golden Purslane has become an on farm favorite salad green. It has a juicy refreshing taste with a sour edge that livens up a salad.

Last year we also grew a seed crop.

1 Purslane

Golden Purslane produces small yellow flowers that only last a short time. (I have yet to catch them in picture.) They then form a small green fruit in the center of the leaves. After a bit you can peel off the cap of this fruit to find some small black seed.

I was told that this is the perfect time to pull purslane plants for seed. So we did.

2 Harvesting Purslane

We cut the whole plants and packed them into bins to bring them back to the  barn.

3 Purslane bins

The succulent plants were still juicy and delicious at this point.

4 Post Harvest Purslane

We spread the plants out in a single layer on a tarp and added a few fans for ventilation.

5 Purslane Seeds Maturing

Over the next month the fruit dried up and opened to reveal thousands of small shiny black seeds.

6 Purslane Wilting

The plants stayed succulent for quite a while. After 4-5 weeks the stems started to shrivel. Around that time most of the fruit had opened.

7 Purslane Bits

We took the plants outside and shook them over a big tarp. The seed easily shattered. We tossed the green plants aside and collected the dried chaff and seeds.

8 Screening Purslane Seeds

At this point we proceeded as normal to clean the seed with screens and fans. These plants were full of seed! (Such as we did with this Brassica seed.)

Thanks to Frank Morton and Tom Stearns who told me I should pull these plants. They were right.

The Real Seed Catalogue DIY Seed Cleaner

Here is a video that Ben Gable from the Real Seed Company sent me of their DIY seed cleaner:

Open-Source, DIY Seed Cleaner Plans are also available on their site

If you want to see more DIY seed cleaning equipment, you can view two of my previous post that include the air columns that Patrice Fortier and Greta Kryger built.

Do any of you have homemade seed cleaning equipment you’d love to share with other seed growers?

Also, tomorrow (March 23) there is a free webinar on Breeding for Nutrition in Organic Seed Systems at 2 p.m. Eastern. However you have to register in advance.

Visiting Greta’s Organic Gardens

This post is a little late coming …

On August 25th, 2010, the Eastern Canadian Organic Seed Growers Network (ECOSGN) hosted a field trip to Greta’s Organic Gardens in Ottawa, Ontario. The visit was broken up into

  • A little about Greta,
  • A field walk,
  • A tomato taste test,
  • A peek inside Greta’s seed workshop, and
  • A seed cleaning demonstration.

A Little Bit About Greta

Greta Kryger is a staple at most Seedy Saturdays and Sundays across Quebec and Ontario. Her seeds are also available through her on-line seed catalogue. Greta grows all her own tomato, pepper, eggplant, and melon seed in addition to as many other species as she can fit in to her gardens.

Greta’s Organic Gardens began as a market garden in 1991. She began saving seeds and  selling at the Ottawa and Toronto Seedy Saturdays in 1992-1993. In the late nineties, she switched from market gardening to 100% seed production. Her production has been certified organic since 2003.

Greta has also been on the ECOSGN steering committee since its first meeting in March 2008.

Field Walk

The morning began with a walk across Greta’s fields.

A few cucurbit species on black geotextile (for weed control).


Some of Greta’s seed crops are also grown in tunnels. This adds heat and isolates plants from  other pollen sources.

These guys make good use of any seed cleaning byproducts (i.e squash and tomato pulp).

Tomato Taste Test

Greta is known for her huge selection of tomatoes. With a couple of volunteers, Greta set up 30 or so sampling stations of different tomatoes.

Tasters rated each tomato from 1 to 5 on different aspects such as taste and  appearance.

A Peek Into Greta’s Seed Workshop/Greenhouse

This greenhouse is Greta’s seed wonderland with an aquatic garden and heat loving plants.

The controlled climate let’s Greta collect seed from many plants that might not set much seed in our climate.

In one corner of the greenhouse, tomatoes are fermenting.

Tomato seeds are placed on screens (these are actually pepper seeds.)

Then stacked to dry.

Greta also brings seed crops into the greenhouse to dry out of the rain.

Some seed crops are hung in pillow cases to dry.

Seed Cleaning Demonstration

Greta uses a set of seed screens (also notice the colander collection in the upper left corner) to remove most of the chaff from her seeds. The final cleaning of most crops is done with this air column:

Dirty seeds go in the top right pipe. Lighter material (dirt, dust, chaff) is blown out the top of the long pipe. Heavier material (seeds and maybe stones) are collected from the bottom of the pipe.

The air column is powered by a bathroom fan with a dimmer switch.

(Compare this with Patrice Fortier’s air column.)

Thanks Greta for a great farm tour and a great farm lunch – the turkey meat balls were especially good!

ECOSGN is currently planning more great seedy events – more details soon …

Cleaning Lettuce Seed

Lettuce is the other seeed crop that took me years to learn how to clean well (radishes being the first).

The basics are like other dry seeded crops (thresh, screen and winnow ad nauseam) but to do a good job I’ve had to pay a lot of attention to the threshing and final screening.

(If you want to read more about growing lettuce for seed : growing lettuce seed under field tunnels  and growing out crossed-up lettuce seed)

Harvesting Lettuce Seed

I keep a regular eye on the lettuce plants to catch them as they flower.

After flowering, the lettuce blooms close up.

A couple of weeks later, the flowers open again to reveal little fluffies at the end of mature seed (kind of like dandelions).

Since the seed doesn’t all mature at once, some folks walk their lettuce patch every couple days and shake the plants into bins or paper backets to collect the seed. I’ve tried this approach but don’t have the time to handle the plants this regularly.

Instead, when about 1/2 the flowers are mature, I harvest the whole plant.

I cut the plants above the roots (keeping dirt in the garden!), pile them in bins, and bring them back to the barn.

Drying Lettuce Seed Plants

I spread the lettuce plants out on tarps with a fan blowing air over them. I rotate the plants at least once a day so that the leaves dry down rather than rot.

If I have a little lots, I dry them upside down in a bucket.

The lettuce plants usually dry for 1-2 months before I process the seed. By this time the plants are completely dry and most of the seed has matured.

Threshing Lettuce Seed

Whereas we now stomp most seed crops to thresh them, we put on kid gloves to handle lettuce.

We rub the plants vigorously between our hands so the flowers fall apart dropping the seed and fluff.

This leaves the stems bare. I try not to break many stem pieces into the mix as they can be tough to later extract.

Screening Lettuce Seed (First Time)

I usually skip the 1/2″ screen and move right to the 1/4″ screen.

I separate the seed and chaff into the bin below and leave any stem on the screen. This is where cleaning lettuce seed gets tricky because the chaff is similar in weight to the seed and the fluff doesn’t seem to want to let go.

At this point I turn to more specialized equipment.

Screening Lettuce Seed (SeconD Time)

This is my favorite colander. The size of the holes are perfect for little oblong seeds (such as lettuce).

I rub the chaff-seed mix through.

This extracts the coarse material. I use this screen a few times and wind up with seed and a bit of fluff.

Winnowing Lettuce Seed

At this point I winnow delicately. If the seed is still dirty. I winnow again a bit more aggressively and perhaps run the seed through my colander another time.

One of the biggest tricks I’ve learned is to not try to save every last seed. When I accept losing a bit of seed, I can get the remaining seed much cleaner.

This is about as clean as I can get most lots with screens and fans. I pick out some of the remaining bits but have to live with the rest.

I apologize for the delay in getting this post up (Brian Creelman has been asking me to post about lettuce for nearly a year.)

Some of the delay is because I’m not much of a lettuce seed man – I’ve often had trouble getting lettuce seed crops to maturity and even though I’ve been cleaning lettuce seed 10 years, I still can’t get it as clean as most other seed. I’m currently looking into some seed screens from Hoffman Manufacturing. If these work out maybe I’ll become a lettuce seed cleaning maniac. I’ll keep you posted!

The rest of the delay is that I’ve been conference and workshop hopping this past month and any my spare time has been going into our new website. I’ll tell you guys more about all that soon …

Special Seed Winnowing Bucket

On my last post, Xander commented on the bucket I was using to winnow radish seed. The bucket in question in one of the 2011 additions  to my seed cleaning arsenal. Here a few shots of this bucket in action:

Restricting seed and chaff flow rate

I use this modified bucket to restrict the amount of material falling at once and pour a steady stream of material in front of the winnowing fans.

I used an old wooden field marker as the bar and fixed it in place with duct tape. This works better on a bucket with straight sides.

Usually the material flows easily through the gap. Sometimes the chaff gets stuck and blocks the flow.

Increasing flow rate

I use a finger to dislodge any stuck material.

Decreasing flow rate

If on the other hand material is going through too quickly, I use my hand to hold some of the chaff back. I might also do this if the chaff threatens to pour over the bar instead of under!

Anybody have any equally handy high-tech seed cleaning equipment?

Also, happy new year!

Saving Radish Seed With Gusto!

As a new seed saver I used to work delicately with seed crops to avoid any damage and minimize seed loss. This worked well for plants like arugula that have seed that shatters easily and light chaff. But radishes, with their big spongy pods that squished before shattering and left pieces of pod the same size as the seed, gave me a headache. And after a couple miserable attempts, I gave up on radishes for many years.

Four years ago, with some seed saving experience, I tried radishes again with success. The differences in my approach came down to making sure the pods were very dry and not being too delicate with the extraction process (quite the opposite in fact!).

I clean  radish seeds with multiple cycles of threshing, screening and winnow steps in my radish cleaning. This is what I call aggressive seed cleaning and use this approach with seeds that don’t easily shatter (snap beans, and now chicory, fall in this list).

This post covers the radish seed cleaning,  you can read about growing the plants for seed here:

On with the cleaning!

Primary Threshing

We harvest the plants when they’ve dried down in the field. Then let them dry further in the barn

When they are dry, I put the plants in a bin and stomp them with my boots.

I screen out the plant stems and largest material with a 1/2″ screen.

This is what fell through the screen. There are still a lot of whole pods in here.

I run this through a 1/4″ screen. The whole pods stay on top.

This is the chaff and seed (with a few whole pods) that went through the second screen. I leave this in a bin and pay attention to the pods that didn’t fall through.

secondary Threshing

This is what didn’t go through the screen.

I stomp on the pods some more and then screen again the 1/4″ screen. I add what falls through the screen to the bin with what fell through during the previous step. I repeat with any pods that didn’t fall through the mesh.

After a few passes all the plant material has fallen through the 1/4″ screen and is collected in one bin.

I take this bin into the barn.


I transfer the chaff and seed to a bucket and then winnow.

I start with the fans on low-speed and crank the speed each successive pass till I achieve desired results. In the case of radish seed both fans are at high-speed.

I winnow over three bins on a tarp. I can recuperate my seeds if I have a fanning mishap, and also I can see what is being separated at different steps.

The left bin (closest to the fan) is full of seed and non-shattered pods. The bin on the right is full of stems and shattered pods.


Repeat Threshing And Winnowing

I compost the plant matter from the bin on the right and screen the bin on the left with my 1/4″ screen. crushing anything that doesn’t go through with my boots.

After another cycle or two of screening and winnowing, the large plant matter has been removed from the seed.

Only the seeds remain with a few big bits. At this point I take out my specialized radish screen.

Final Screening

This is one of my fine collection of colanders, the square  holes are the right size for radish seed.

I pour the seed into the colander and delicately shake from side to side …

separating the last bits from the seed lot.

I lay the clean seeds on a tray to dry a few more days than bag them up to bring them into the office.

Key Lessons

As you can see I really kick the seeds out of those pods – hence aggressive seed cleaning. Getting the seeds free from the pods is the critical first step in seed cleaning. From that point on screens and fans can do the rest.

Next, I’ll talk about how aggressive winnowing does the job for lettuce seed.

10 Steps For Getting Seed As Clean As Possible

In my early seed-saving days, I’d thresh and I’d winnow but I just couldn’t get my seeds as clean as when those that came from a seed packet.

Over the next dozen years, meeting experienced seed growers, reading piles of seed production books,  and attending whatever seed workshops I could find; I gleaned many pearls of wisdom that I then fine-tuned cleaning hundreds, if not thousands, of seed lots.

Here are the steps and lessons that have had the biggest impact in my seed saving career:

10 Steps For Getting Seed As Clean As Possible

  1. Make sure plant material is dry, dry, dry before threshing. In Eastern Canada, it can be hard to get a crop to dry in the field. Harvest whole plants when they are 3/4 dry. Spread them on tarps in a greenhouse with fans to increase ventilation and turn them periodically to ensure even drying.
  2. Leave dirt in the field. Leave dirty plant roots in the field when you harvest seed crops. It is much easier to not add dirt to your seed than to remove it later.
  3. Clean seeds on a dry day. Even if your seed crops are very dry, ambient humidity on an overcast or rainy will make seeds stick to the chaff.
  4. Thresh aggressively if seeds don’t easily shatter. Use boots, sticks,  rakes, tractors, and trucks to shatter seeds from pods.
  5. Alternate screening and winnowing to blow away the light chaff and separate plant material into 2 groups:
    • Threshed seed and small bits of stem, pods, and rocks.
    • Larger plant material that contains unthreshed seed.
  6. Repeat steps 4 and 5 with larger plant material until you only have bins of threshed seed with small bits of stem, pods, and rocks that are the same size and weight.
  7. Winnow threshed seed aggressively to remove other material of similar size and weight.
  8. Screen seed carefully. Seed usually falls through first. Stop screening when most of the seed has fallen through.
  9. Be willing to sacrifice seed as you repeat steps 7 and 8. If you focus on getting seed clean rather than on saving every last seed, you can get seed a lot cleaner.
  10. Remove any remaining unwanted elements by hand. I usually spread seeds on a baking tray and do a final triage to remove broken and damaged seed, and any other remaining bits.

Seed saving examples

You can see all these principles in action in these two posts:

And in the next couple of posts I’ll demonstrate these principles for two crops that used to really give me a headache: radishes and lettuce.

Are there any tricks or lessons that really improved your seed saving?