Issue 13, February 2008

Summer is a great time for travelling. For the last three years, I have been going to the Taranaki Summer Orchid Display in New Plymouth. It is a small display of orchids that are not normally in flower during the regular orchid show season. Take for example, Disa orchid. It normally flowers over Christmas through to February. The summer show probably has the biggest display of disa orchids in New Zealand.

The country should now be experiencing the begining of autumnal weather. It will start to cool down and the weather will be more settled. In the veggie garden, harvesting should be in full swing. When harvesting, keep in mind next year's planting, and save seeds along with the harvest. Therefore, the theme for this month's newsletter is Saving Seeds.

Taranaki Mt. Egmont, shot at Mokau, on my way to New Plymouth.

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Today, it is relatively easy to go out and buy plants and seeds. Many different types of vegetable and flower seeds are available through garden centres and mail order nurseries. So why save seeds? There are many reasons.

Growing from seed is a higher plant's primary way of reproduction. In the production of seed, plants' genes are mixed and the resultant offsprings have subtle variations. These variations ensure that when the species is under threat, chances are there will be a few offsprings that will have some resistance to the threat. For example, if a new bug were to start eating the plant, there may be a chance seedling that produces chemicals that repel the bug. This seedling will be more successful than its siblings and will pass its genes on to its offspings. In time, a new variety of the species will arise that is resistent to the new bug.

There are plants that are able to reproduce without needing seeds. These forms of asexual reproduction can produce a population of clones, lacking the ability to adapt to changing conditions. This ability to clone has been exploited to mass produce identical plants. There are advantages for agriculture, for it is then possible to guarantee the quantity and quality of harvest. For more information, see Clone the Garden.

Having said that, compared to other forms of propagation, starting plants from seed requires the least amount of effort. Even for plants that have been mericloned by the thousands in the laboratory, breeders are now developing seed lines that breed true to type. Furthermre, Seeds can be stored, sometimes for many years, and can be used as a backup, to preserve a species or variety.

The seeds of heirloom and unusual varieties of vegetables and flowers are not commonly for sale. Saving your own seed is often the only way to keep these varieties.

Pollination
Cross Pollination
Selection
In-breeding Depression
What to save
When not to Save Seeds
Collecting Seeds
Cleaning Seeds
Storing Seeds
Labelling

Seed production starts with pollination. Most plants require pollen to be transferred from one flower to another to set seeds. Pollen can be transferred by the wind (eg. grasses), birds (eg. fuchsia), or more commonly insects. Some plants, such as tomatoes, self pollinate. On a tomato flower, the pollen drops down to the stigma and self pollinates the flower. In extreme cases, such as for beans and peas, the flower is pollinated even before it opens!

Most plants however, do not self pollinate and will not set seed unless pollinated. The most common failure for plants not setting fruit or seed is inadequate pollination. It could be that the floers have opened too early and bees are not yet out and about. It could be that wild bees have been wiped out by the Varoa mite. Another possibility could be the plant has a natural pollinator, but when taken out of its native habitat, there are no suitable pollinators.

If the plant cannot be pollinated naturally, it is necessary to use hand pollination. For plants with big flowers that produce ample amounts of pollen, this is a simple task of brushing to pollen on to the stigma. Even for self pollinated plants, such as tomatoes, during periods of calm weather, it may be necessary to gently tap the plants to ensure that the pollen drops on to the stigma. Commercial kiwi fruit orchids employ bee keepers to pollinate their crop. Sometimes manual pollination is used.

A number of plants require cross pollination in order to set seed. Only the pollen from a different plant will set seed. The pollen must come from a genetically distinct plant, not just a clone. For example, most feijoa will only fruit if two or more varieties are plant close to each other. Planting two plants (or clones) of the same variety will not achieve cross pollination. Even for plants that do not require cross pollination, the seedlings that result from cross pollination tend to be more vigourous.

There is also a down side to cross pollination. For many plants, different varieties, and even different species and genera, will cross with each other. This is beneficial to the hybrider, but presents problems for the seed saver wanting to keep the variety pure. Pollen from another variety must be excluded.

There are several ways to prevent one variety from crossing with another. The safest way is to physically separate the varieties. For wind pollinated plants, such as cord, this means separation of several kilometres, not practical for home gardeners. Certain plants, such as tomatoes and chillies, will self pollinate, but can be also be insect or wind pollinated. There should be around 3-4 metres of space between different varieties.

Insect pollinated plants should be separated by a distance of at least 10 metres, preferbly with a row of taller flowering plants separating them. The other method is to place fine mesh screens around the plants. Keep the mesh between two varieties on alternate days. This will ensure that insects only pollinte one variety at a time.

Some plants that produce a large amount of seeds from one flower. It is possible to hand pollinate these plants. For example, pumpkin and other members of the melons family, produces fruits with plenty of seeds. They also produce separate male and female flowers. Pollen should be transferred early in the morning, before bees are out and about, and a stocking placed over the female flower for the day.

Peas and beans can be grown side by side because they are self pollinated, and by the time the flower opens, it has already been pollinated. It is very rare for different varieties of beans and peas to cross pollinate.

When collecting seeds, the gardener is inadvertedly selecting plants. Seeds should only be collected from healthy and vigorous plants. When saving seeds of vegetables and fruit, try and save the seeds produced in the middle part of the main season, or ones produced just prior. When saving seeds of flowers, try and get the first seeds produced, as these will often be the best quality, with the most viable seeds.

Through a process of selection, it is also possible to end up with breeds that are more suited to the conditions in your gardens. For example, if you consistently get late frosts, then try and save seeds from those plants that flower later. This way, you may be able to gradually move the main flowering season out of frost danger.

Hybrid vigour is a phenomenon where seedlings resulting from a cross between two inbred lines have exceptional vigour compared to their parents. The opposite of hybrid vigour is inbred depression. Different plants suffer to different degrees, but in general, seedlings resulting from self crosses tend to be weaker. When saving seeds, it is best to save seeds from a larger number of plants. This ensures that succeding generations still have enough of a gene pool to avoid inbred depression.

Only seeds from open pollinated varieties should be saved. This includes vegetables such as tomato, most melons and chillies, and herbs such as coriander and basil. Seeds from annuals, or plant grown as annuals, are the easiest to collect. Simply grow the plant to maturity, allow it to flower and fruit, then collect the seeds when the fruit is ripe. Certain perennials (such as chillies) are grown as annuals, and may require a long growing season, and for these, it is necessary to start the seeds indoors at the end of winter. Allow the seedlings to grow indoors until planting time in late spring. This gives the plant a head start, giving it more time to produce seed.

Biennials, such as parsley and carrot, must be planted and grown for two years before they will flower and set seed. For parsley, allow the plant to keep growing until it flowers. A small amount of leaves can be harvested without affecting the quality of seed. For carrots, leave a few carrots to over winter. The following season, the carrots will sprout, flower then set seed.

With perennials, it is best to propagate vegetatively, such as by cuttings or division of the crown. Certain perennials, such as Aquilegia, Echinacea and balloon flower, can also be propagated through seeds. These perennials typically only flower from their second year. Leave the dead flower heads on and allow then to set seed.

F1 (First Filial) hybrids are created by crossing two in-bred lines to produce seedlings with desirable traits, such as vigour. The second generation (F2) seedlings tend to revert back to their parents, or at least a number will have undesirable traits. It is not worthwhile to save seeds from these hybrids. Examples of F1 hybrids are most modern corn varieties, certain broccoli, cauli, capsicum and melons.

Fruit trees are usually propagated by grafting a highly selected variety on to a rootstock. As the scion wood is already mature, these trees tend to only take a couple of years to start producing, and as a result, it is possible to have smaller sized fruiting trees. Seedling trees will take much longer to start producing, and the trees need to grow quite large. Furthermore, there is no guarantee that the seedling tree will produce the same fruit, and it will most likely not. For the average home gardener, it is not worth the risk taking many years growing seedling trees, only to find out that the fruit is not good.

A number of ornamentals, for example, shrubs, certain perennials and most bulbs are also produced through vegetative methods. These tend to be also highly selected. Seedlings will usually be quite different from their parents. This trait is exploited by plant breeders to produce new varieties.

There are a number of plants that do not readily grow from seed. Here are a few examples. Tahitian lime is a sterile hybrid and does not set seed. Most varieties of garlic require cross pollination with another variety to set seed. Garlic is usually grown through planting cloves. Orchids produce microscopic seeds that require a lab for germination.

Seed should only be collected when they are ripe. This may or may not coincide with the ripeness of the fruit. For example, several varieties of melons will only have half ripe seeds when the melons are picked. If these are then left to cure, the seed then ripens.

Pods and capsules that explode or split to release seeds should be harvested just before they burst. This is usually just before they change colour, but colour may not be a reliable indicator. When in doubt, a fine mesh bag can be placed over the pod or group of pods to catch the seeds as they are released.

Poppy seed heads should be cut just before they turn brown, and before the head opens to release seed. Hand these up side down in a paper bag and place in a dark, cool, dry place, such as a garage. In time, the seeds will fall to the bottom of the bag. The bag can be shaken from time to time to accelerate the process. Foxglove, snapdragon and aquilegia seeds can be similarly treated. On these, the seeds ripen at different times. The whole flower spike should be cut off when the majoity of seeds show signs signs of ripening.

Soft fleshy fruit should be lightly crushed and soaked in a bowl of water for a couple of days. Fungus and bacteria will ferment the pulp, releasing the seeds. Viable seeds will sink to the bottom while empty seeds float to the top. The softened pulp and other debris can then be washed from the seeds. Fermentation also produces reactions that later protect the seedlings from fungal and bacterial attack during germination.

Chilly and pepper seeds can be saved by scraping the seeds from the chillies. Alternatively, allow the chillies to dry out naturally. Break off the bottom end and gently squeeze the seeds out.

Plants from the daisy family produce seeds in the flower head. These should be cut from the plant when ripe, then allowed to dry. The seeds will either fall off naturally or can be easily teased off. Winnow and sieve to remove any chaff.

Seeds should be dried before being stored. Inadequately dried seeds will not keep well. Seeds should be dried in a cool dry place. Larger seeds will take longer to dry than small ones.

Certain types of seeds will not dry and keep. These should be sown as soon as they are collected. Most fleshy seeds from tropical plants fall into this category. Certain New Zealand plant seeds also do not keep well.

Once dried, seeds should be placed in an air tight container and stored in a dark, cool, dry place. To store seeds in a fridge (not freezer), place silica gel (or another dessicant) into the container. Othereise, the moisture in the fridge will spoil the seeds.

It is important to correctly label stored seeds. Seeds from different plant and varieties can look alike. If the seed is not labeled, the only way to tell the difference is to germinate the seeds and see what sort of plant results. To tell different varieties, it is often necessary to then grow the plant to flowering or fruiting size.

Seeds only last for a finite time in storage. Most often only last two years. Certain seeds such as parsley only last one year. Old seeds either germinate poorly or not at all. The seed label should also contain the date in which the seed was harvested. This allows old seed to be discarded.

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Area: Warmer Colder

Sow these seeds:
Aquilegia
Cape Gooseberry
Cineraria
Coreopsis tinctoria - Golden
Coreopsis tinctoria - Dwarf Red
Cornflower
Parsley
Foxglove
Fuchsia boliviana
Fuchsia procumbens
Gaillardia pulchella
Giant Geranium
Kaka beak
Kowhai
Living Stones
Sweet Williams

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