THE BASICS OF SAVING YOUR OWN VEGETABLE SEEDS
For more information on specific crops, please refer to our species specific gardening guide section of the site!
You can also join up to our dedicated NZ Seed Savers Facebook group and ask any questions that you may have.
KEY PRINCIPLES OF SEED SAVING
There are a few things that are the most important to keep in mind when saving seed. More specific concepts are discussed below but fundamentally, successfully saving seed depends on
Saving seeds from a good number of plants. Saving seed from one or two plants can result in a weakening of the genetic diversity known as a 'genetic bottleneck'. As a rule of thumb, save seeds from a patch of at least ten healthy selected plants. But more is always better where possible.
Avoid cross pollination with other varieties. Ensure that only one variety of a certain species is flowering in the vicinity at any one time. More detail below.
Ensure that seeds develop to full maturity before harvesting them. Under ripe seeds will be lacking in vigour and have poor viability and lifespan. Generally seeds are ripe when they are plump and hard and the plant is beginning to brown off and die. Soft green seeds or seed pods are not ripe yet.
Harvest Seeds From the Healthiest Plants
The seeds from healthy plants will tend to be healthiest. Stunted or sickly plants should not be harvested for seeds.
Preserve Genetic Diversity
Within each strain of open pollinated or heirloom vegetable there exist 'sublines' which represent genetic diversity. This means that there is a slight degree of variability within the plants. Some might mature slightly later, some slightly earlier, some might favour slightly drier or wetter conditions, and so-on. While you loose a little bit of uniformity (but hey, uniformity is boring anyway, right?) what you gain is the resilience of your vegetable strain to a range of environmental conditions. To preserve this resiliency and genetic diversity, a good rule of thumb is to save seed from at least 10 plants from your crop. And of course be sure to make these ten of the best!
Gather Seeds Only From Representative Plants
Gather seeds only from representative plants which have the characteristics you're wanting to promote, not tiny or diseased ones. Pick ones from plants that produce the flavor and vigor you are trying to preserve.
Avoid Cross Pollination Between Varieties
When saving vegetable seeds it is very important to keep a variety 'true to type'. You want to know that the seeds planted next year will be representative of the plants you saved seeds from, rather than an unpredictable cross.
As such it's important to make sure that only one variety of any given species is flowering at any one time. And don't forget that all brassicas (broccoli, cabbage, cauliflower, kale, brussel sprouts etc) can cross with one another, and the same goes for beetroot and silver beet!
It's always tempting to attempt some whacky 'crossing' experiments, and by all means do, however they are often very unpredictable and it can take years of careful work to stabilise a new variety. So it pays to do some reliable single-variety seed saving alongside your experimentations! NOTE: This does not apply to self-pollinating plants like peas, beans, lettuce and tomatoes.
Choose Mature, Ripe Fruits or seed heads
Choose mature, ripe fruits or seed heads for seed harvesting. An unripe fruit or seed head may have immature seeds, which aren't going to be as viable. In general, seeds are ready when fruits become ripe, or when seed-heading plants begin to dry off. Mature seeds are usually a dark or tan colour, as opposed to green.
To be Able to Share Your Seeds
To be able to share your seeds, harvest more than you can use, saving some for a dry year, and some for trading or giving away.
Don't Mix Varieties When Harvesting
Don't mix varieties when harvesting, and label them clearly as you harvest them.
Clean the Seeds Well
Clean the seeds well, rinsing off any vegetable matter and spreading to dry thoroughly on a towel, newspaper, or pie tin. Stir seeds daily so they can fully dry, or transfer to a brown paper bag to continue drying.
Beans and Peas Can Be Left on the Vine
Beans and Peas can be left on the vine to dry in their pods, either in the garden, or in a cool dry place inside. Beware of mildew as autumn approaches - hanging plants under shelter can prevent fungal rot.
For Seeds Not Produced in a Fruit
For seeds not produced in a fruit, like lettuce or spinach, leave the seed heads on the plant until dried, or cut when mature and bring inside to dry completely. Put the seed heads in a small paper bag and rub between your fingers to remove the seeds.
When the Seeds are Fully Dried
When the seeds are fully dried, store them in small envelopes, prescription bottles, baby food jars, spice jars etc. Placing the small envelopes in a jar helps to ensure they stay dry. Be sure to label the container well with the variety and any other planting notes to yourself.
Seeds Should be Stored in a Cool, Dry Location
Seeds should be stored in a cool, dry and dark location. The seeds are best planted the next year, but some varieties stay fertile for up to five years.
Maintaining vs. Modifying a Vegetable Variety
I would like to discuss two different approaches to seed saving. These are 'maintaining' as compared to 'modifying' a variety.
For both approaches, the basic seed saving techniques remain the same. The difference lies in the selection of which plants to save seed from, and the method that is chosen depends on the goals of your seed saving efforts.
If it is desired to retain the 'true type' characteristics of a variety, a maintenance approach should be taken, whereas if you desire to develop or 'improve' the varety to have altered characteristics or greater suitability to your conditions, then a modification approach should be taken. In practice, there's no reason why you can't do both at the same time, but seeds of each approach should be kept separate because of their different purposes.
Let's use peas as an example.
Say you have an heirloom variety of peas that you are saving seeds from. The characteristics of this strain have been selected for generations, for various reasons. Because of this, it could be seen as important to preserve these characteristics. This could be especially relevant if you are returning your seeds to a local seed savers network. Also in the case of heirloom varieties many people like to try and preserve them the way that they were many years ago.
However, you may also wish to further adapt the variety to your own conditions, or select for characteristics that you prefer.
It should be noted here that we are talking about 'within variety' selection, as opposed to creating 'crosses' between different varieties of the same species.
So in this case we are talking about growing a group of plants from the same open-pollinated seed stock, that are isolated to the necessary distance from any other varieties, depending on how they are pollinated (wind/insect pollinated plants require greater distance between them than self-pollinating plants to avoid unwanted crossing).
Regardless of which approach is used, rogueing should always be practiced. This is the process of removing any plants from your crop which are unhealthy, lacking vigour, have bolted to seed early, exhibiting signs of disease, stunted, detrimentally mutated, and so on. Seeds should always only be saved from healthy plants. This is the most fundamental form of 'selection' undertaken by a seed saving gardener.
MAINTAINING A VARIETY
If you are wanting to maintain a variety, you need to save seeds from plants that are 'true to type' / 'normal' for the variety. In other words, you'll be saving the seeds from the middle of the spectrum of variation that you see within your group of plants. Of course, healthy plants should always be selected for seed saving, but what we are talking about is the general characteristics of the plant - height, pod size, bushyness, etc.
Using this approach, you're avoiding saving things that are at the 'extreme' ends of the spectrum of observable traits, even if these ends of the spectrum seem 'better' in your own opinion.
IMPROVING / MODIFYING A VARIETY
It may be that you have a desire to modify, or 'improve' a variety to better suit your growing conditions or preferences. By saving seeds from plants that lie at a a particular end of the spectrum of traits seen in your group of plants, you can begin to further 'breed' the variety. Many changes happen slowly and it can take at least a few seasons to make any drastic changes for some varieties.
For example, you may want to have pea plants that grow taller, or have bigger peas, or more peas in each pod. Or you may want ones that can be sown earlier in the winter for an extra early spring crop of peas.
To do this, you will need to carefully select seeds from plants that exhibit the characteristics that you are looking for. I emphasise 'plants' because it is the whole plant that you need to look at - not just the individual fruits or pods.
So say you are working with a pea variety that normally has around 7 peas per pod but you are aiming to increase this to 8 or 9 peas per pod. In your first year, most of the plants will have 7 peas per pod. Some plants might have 5 or 10 pods with 8-9 peas in them whereas others may have just the odd fluke pod that has 8 or 9 peas. You need to be sure to save the peas from the plants which have the most pods with a higher number of peas in them.
If you are wishing to extend the growing season of a variety, you will need to plant seeds earlier than normal (or later than normal if selecting for extendability into autumn).
This may well result in the majority of your crop dying from frost. But if seeds from the plants that do survive are saved for a few years in a row, cold-hardiness will be selected for and you will have a stronger variety.
Seed selecting for cold hardiness is a fairly experimental pursuit, and obviously the further you push the limits, the greater the risk of loosing all of your plants. As such, these kinds of experiments should only be preformed on varieties which there is ample seed stocks of. And it also pays to plant out a crop at the normal time as well to provide you with your food (although of course be aware of cross pollination if the plants are flowering at the same time).