Garden Fundamentals - Learn about plants and gardening

Collecting Seed – Great Way To Propagate Plants

Collecting seed is an easy and cheap way to propagate and share plants. It allows you to make more of your own plants or add new types of plants to your garden. You can collect from both gardens and the wild, and it is a great pastime when you are traveling.

In this post I will describe different types of seed and help you determine when they are ready to collect.

collecting seed from clematis seed head (achene) by Robert Pavlis

Clematis seed head (achene), by Robert Pavlis

Can I Grow That From Seed?

One of the most surprising questions I see in social media is, can I grow that plant from seed? People are surprised to learn that all plants come from seed. Granted they can also be propagated by tissue culture and cuttings, but this can only happen once the original parent is grown from seed. All perennials, bulbs, grasses, trees and shrubs grow from seed.

I’ve built up a large collection of different plants from seed and each year I start anywhere from 40 to 200 different ones. This is mostly from seed that others have collected and donated to seed exchange programs. I do the same in my garden. I collect seed each fall and send them to different seed exchanges for others to use.

Having said this, there are some sterile plants that do not form seeds. When it comes to collecting and germinating seeds there are exceptions to every rule.

Where Do You Find The Seed?

collecting seed - hosta seed head, by Robert Pavlis

Hosta seed head, by Robert Pavlis

I am now talking about collecting your own seed and how to find it on the plant. In most cases, seed is formed at the base of the old flower after the flower is pollinated. As the flower fades away, the base starts to swell and form a seed compartment. As this process continues, the compartment and the seeds inside mature. The plant keeps feeding the seed during this process so ideally they should not be harvested until they are mature and fully developed. In most cases, immature seeds will not germinate properly.

The key to collecting seed is to know when they are ripe. For most plants this is fairly easy to determine as explained below but for some this can be tricky.

There are also some plants that form seeds in unexpected places. Some of the large sundrops (Oenothera species) form the seed pod at the base of the plant several inches away from the old flower.

collecting seed - hosta seed capsule, by Robert Pavlis

Hosta seed capsule that is still green. Is it ready to collect? , by Robert Pavlis

 

collecting seed - hosta seed capsule by Robert Pavlis

The same hosta seed capsule showing black seeds that are ready to collect. You do not always have to wait for the seed capsule to turn brown, but waiting does no harm, by Robert Pavlis

Types of Seed Fruit

The botanical name for the part of a plant that contains the seed is called the fruit. Don’t confuse that with the common culinary definition of the word fruit – the thing we eat. The fruit that produces seeds can take many different forms but to keep things simple and practicable I’ll discuss the 3 main types that you are most likely to encounter in your garden: hard capsule, fleshy fruit and achene (ball of fluff – hows that for a scientific name?) For a more detailed description of different types of seed fruits see Fruits.

Hard Seed Capsule

collecting seed Penstemon hard seed capsule starting to open. This is the perfect time to collect the seed, by Robert Pavlis

Penstemon hirsutus hard seed capsule starting to open. This is the perfect time to collect the seed, by Robert Pavlis

When someone mentions seed collecting, this is probably what you picture in your mind. This is a hard or semi-hard structure that contains seed.  The picture to the right shows a very typical dry seed capsule from Penstemon hirsutus. The picture above of the hosta seed capsule is also a hard capsule type, except that the one in the picture is still green.

If you open the capsule you will see the seed inside. The capsule is normally ripe when it is dry. A green capsule tells you the seed is not yet ripe, but the hosta pictured above is an example of where this rule does not work.

The seed may stay attached to the capsule, but in most cases it becomes loose once it’s ripe.

collecting seed Allium cristophii seed head with the seed capsules opening up to show the ripe seed, by Robert Pavlis

Allium cristophii seed head with the seed capsules opening up to show the ripe seed, by Robert Pavlis

collecting seed Primula hard seed capsule. The capsule is open and some of the seed has already spilled out, by Robert Pavlis

Primula hard seed capsule. The capsule is open and some of the seed has already spilled out, by Robert Pavlis

 

collecting seed - Ripe seed collected from the above Primula capsules. Plenty of seed left for the home gardener, by Robert Pavlis

Ripe seed collected from the above Primula capsules. Plenty of seed left for the home gardener, by Robert Pavlis

Fleshy Fruit

Mountain ash fruit cluster ready for collecting seed, by Robert Pavlis

Mountain ash fruit cluster ready for collecting seed, by Robert Pavlis

Many seeds are formed inside a fleshy fruit, like an apple or a tomato. Botanically speaking a tomato is a fruit. Some fruits contain several seeds and others like the cherry contain a single seed.

Fleshy fruit is more common on trees and shrubs, but some perennials, like the jack-in-pulpit also form fleshy fruits.

The seed is usually ripe a week or two before the fruit is fully ripe. In some cases the fruit dries out and forms a tight covering over the seed. The mountain ash shown to the right is ready for harvest; it is over-ripe and starting to shrivel. If you open one of the fruits you will see the small tan-colored seeds inside.

Because the fruit never really dries out to form a capsule, the seeds never become loose. Collecting them is easy, but this type of seed does require some special treatment to separate the seed from the fruit.

Achene (ball of fluff)

collecting seed Seed head from Gaillardia. Note the fuzzy head and lack of a capsule, by Robert Pavlis

Seed head from galardia. Note the fuzzy head and lack of a capsule, by Robert Pavlis

Quite a few garden plants produce seeds without any container holding them together and the dandelion is a good example of this. This seed head consists of a ball of fluffy seeds, hence the common name I have given this type of seed. Botanically they are called achene (pronounced, ay-keen).

The seed usually consists of two parts, the real seed at the bottom with a tail or fluffy top. Many of these seeds are designed to disperse by wind.

The clematis seed shown at the top of this post is a good example, as is the galardia (blanket flower) shown at the right.

The easiest way to collect this seed is to just grab the whole seed head and pull it off.

Achene seed head of a native aster, by Robert Pavlis

Achene seed head of a native aster, by Robert Pavlis

Color of Ripe Seed

Immature seed is usually white or green and as it matures it becomes tan, brown or black. When the seed develops in a fruit, it is still brown or black, but may look colored because of the fruit. A magnolia seed looks bright orange but the orange part is really the fruit, not the seed.

collecting seeds - Magnolia fruit cluster on the left showing what looks like orange/red seeds. Once the fruit is removed from the seed they are black (three on the right side), by Robert Pavlis

Magnolia fruit cluster on the left showing what looks like orange/red seeds. Once the seed is removed from the fruit they are black (three on the right side), by Robert Pavlis

Seeds Don’t All Ripen At The Same Time

Most plants flower over a number of days or weeks and their corresponding seeds also ripen over a period of time. This is important for the plant since it increases the chance that some will survive and grow into seedlings.

collecting seed Crocosmia flower heads open a couple of flowers at a time from the bottom up. Consequently, the seeds mature in the same sequence. In this photo the left ones are ready for harvest, by Robert Pavlis

Crocosmia flower heads open a couple of flowers at a time from the bottom up. Consequently, the seeds mature in the same sequence. In this photo the ones on the left are ready for harvest, by Robert Pavlis

It is a good idea to visit the plant every few days to see how the seeds are progressing. In many cases, like the crocosmia in the above picture, some seeds will be mature and ready to harvest while others will still be green. Collect only the ones that are ripe.

Does Seed Need to Be Fully Ripe Before Harvesting It?

Ideally seed should be fully ripe before harvesting. If you harvest too early, the seed will not have gotten enough food from the mother plant to complete development and may never germinate properly.

However, many seeds can be collected a bit early and still mature away from the mother plant. If the plant is in your own garden, wait as long as you can and get mature seed. If this is not your garden or you are traveling, collect when you can, and hope they mature.

When Should Seed Be Collected?

Collect seed when it is ripe as described above and in most cases waiting too long is not a problem provided the

collecting seed Iris cristata seed heads covered in organza bags so the seeds are not lost as they mature, by Robert Pavlis

Iris tectorum seed heads covered in organza bags so the seeds are not lost as they mature, by Robert Pavlis

seed waits for you. Many fruits are eaten by animals and if you wait too long you will miss out. Birds also open seed pods to get at seeds.

In other cases the seed pod expels their seed when it is ready. The poppy seed pod develops holes and ripe seed can fall out before you get it. The seed pod of the gas plant is designed so that it propels the seed quite a distant when it is ripe. Wait too long and you will not get any. In such cases it is a good idea to place an organza bag over the seed head before the seed is ripe. That way the ripe seed drops into the bag instead of being lost.

Many North American native plants, like trilliums, produce seed that germinates better if it is a bit immature so it is a good idea to collect early. Besides, ants collect trillium seeds and it is race between you and the ants.

Harvest Seeds From Your Best Plants

If you have more than one plant of a particular type, always harvest from the best plant. How do we define best plant? That is very subjective.

You might have plants with different heights. You could select either the tall one or the short one, depending on your preference. There might be slight differences in flower or leaf color, or one plant might produce larger flowers or more flowers. Select for the quality you want to preserve.

It is also a good idea to select a healthy plant. It might have less mildew, or have fewer bite marks on leaves. Genetics affects how a plant grows in your soil and climatic conditions. Selecting the healthier individual makes it more likely the seedlings will also grow well in your conditions.

Short Growing Season

Plants that flower in late fall in colder regions may never have time to fully develop seeds and you might not be able to collect ripe seed. Here are a couple of examples from my garden.

collecting seed Unique seed capsules from Kirengeshoma palmata. This plant flowers in fall and rarely makes ripe seed before winter stops their growth, by Robert Pavlis

Unique seed capsules from Kirengeshoma palmata. This plant flowers in fall and rarely makes ripe seed before winter stops their growth, by Robert Pavlis

 

collecting seed Inside a seed capsule from Kirengeshoma palmata showing the unripe seed. These will not germinate if collected at this stage, by Robert Pavlis

It is October in zone 5 and Kirengeshoma palmata still has unripe seed. These will not germinate if collected at this stage, by Robert Pavlis

 

collecting seed This poppy is a first year seedling and is flowering very late. This long seed head will not mature before winter, by Robert Pavlis

This poppy is a first year seedling and is flowering very late. This very long seed head will not mature before winter, by Robert Pavlis

Some Plants Don’t Make Seed

There are several reasons why a plant may not make seeds.

Too young – immature plants will not flower and if they don’t flower there will be no seeds.

Unhealthy plants – these may or may not flower, but even if they flower the plant may not have the energy reserves necessary to make seed. Try growing larger, healthier plants.

Sterile – many of today’s annuals and some perennials are sterile. Think about the seedless watermelon. Plants tend to flower until they make some seed. If the genetics of the plant prevents seed formation, they keep on flowering all summer long, a trait that is very popular to gardeners. These plants will not make seeds and because it is due to genetics there is nothing you can do.

Lack of pollinators – flowers need to be pollinated in order to make seed. If the plant requires an external pollinator to do this job and they are not present at the right time, no seeds will be formed. That is a reason why a cold snap in spring can result in lower production on fruit trees. Hand pollination may be an option.

Missing mate – some plants are male or female. Males will never make seed, but even if you have females and there is no suitable mate in the near vicinity, there will be no pollination and therefore no seeds. In this case you need to find a mate – for your plant.

The Power of Seed Exchanges

You might not want more plants of the type you have – so why collect their seed? One good reason is that you can exchange that seed for other seed that you don’t have. The best way to do this is through a seed exchange which have I written about in Seed Exchange – A Great Way To Get Free Seed which explains how they work and lists all kinds of different seed changes.

Other Posts About Growing From Seed

Best Method For Starting Seed Indoors

Plant Seeds – Getting Started  – an introductory guide

 

Seed Starting Videos

Soaking Seeds

Seed Scarification

Germinating Small Seeds

Winter Sowing Method For Seed Germination

Baggy Method For Seed Germination

 

Other Seed Information Blogs

Botanically Inclined – contains lots of specific seed information

 

References:

  1. Fruits; http://theseedsite.co.uk/fruits.html

 

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Robert Pavlis
Editor of GardenFundamentals.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Fundamentals an educational site that helps you understand your garden better.

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