Tuesday 31st October 7pm, at Rhydlewis Hall; A Discussion on Propagation techniques

We met in the hall, a nice crowd of us around a large table to share our knowledge and enjoy having a go at propagation. 

Propagating plants is a rewarding and fascinating process to obtain new plants. Select the appropriate method and timing then follow some basic principles to ensure success.

There are two main kinds: seed (sexual) and vegetative (asexual). 

PROPAGATING WITH SEEDS

Harvest your own seed is fun and just takes a little understanding and planning:

Seed propagation of plants involves fertilisation of pollen and egg leading to seed formation. 

It’s an effective technique for ornamentals or flowering plants, vegetables, fruits, and medicinal plants. It can lead to  genetic diversity and create new varieties and cultivars of plants. Seeds can be stored for a long period of time. Disadvantages are delay in getting a result, non seed producing plants do not produce seeds and identical plants can not be produced.

Seed comes in many different natural packagings, from pepper pots like poppies to hard casings and soft fruits.

What seeds do you collect?

Easy to collect; peas, beans, toms, courgette, squash. Some members had brought seeds to swab, so thank you especially Jeanette, for you runner bean seeds. 

Collecting seed

• Collect ripe seed on a dry day, as soon as the seedheads (e.g. capsules or pods) ripen. This is often indicated by a colour change from green to brown, black or red, but must be before they open and shed their contents
• Pick the seedheads, either singly or on stalks, and lay them out to dry on a greenhouse bench, warm windowsill or in an airing cupboard. This enables seed to be more easily extracted from pods, cones or capsules
• If they don’t open when dry, gently crush pods and capsules to release the seed
• Collect seed from fleshy fruits and berries by mashing them in a fine sieve and then rinsing away the pulp in cold water. Leave the seed to dry for a few days on paper towels
• Place a bag over Exploding seedheads and shake until they explode into the bag. Alternatively, remove the seedheads on their stems as they turn brown and place in a labelled paper bag
• Nuts should be collected around the time they would naturally fall either by hand-picking, or by placing a sheet at the base of the tree and shaking the branch
• After extracting the seed, clean off any surrounding material (chaff) attached to them, as this material could rot and lead to the seed damping off. Chaff can harbour moulds, pests and diseases
• Beans and peas ideally left to dry on the vine or hung in a dry garage. 
• Flower seedheads can ripen quickly, and must be watched carefully in order to collect the seed before they are dispersed
• As a rough guide, seed is set about two months after flowering
• The plants from which you collect seed must be healthy and vigorous. This will help ensure good quality 
• Most seed is best collected when well-developed.
• seed harvested while immature will not germinate
    Some, such as Anemone nemorosa, calendula and Ranunculus are collected when the still look immature and green, but are actually developed
• Collected seeds before they are taken by birds

One member had taken cuttings from a spindle tree growing on her late husband's grave. For personal reasons, she wanted plants for her children that were the progeny of the original bush. The members suggested that taking cuttings is very slow and unsuccessful in Spindle, and we all had a look at how the seeds form inside the pretty red berries. It was recommended that she tried planting the seeds next spring. 

Growing for seed collection

Professional seed collectors grow the plants they will collect from in a separate bed or polytunnel from the other plants.  They need to allow for losses, etc.

Smaller gardens can’t manage this, but try to isolate a strong, good quality specimen and save it for seed collection. 

What are seed potatoes?

David explained that seed potatoes are different from the potatoes that sprout in the kitchen from purchased spuds. 

Seed potatoes are disease–free potatoes that have been selected, tested, and kept in a cool dark place until needed for planting for the next years crop. It was also pointed out that you can keep early seed potatoes by refrigerating them, ready to plant December-ready new potatoes which are planted in July.

Propagating from Supermarkets

Kerry brought three plants that Paul Killick had propogated from supermarket-bought crops; Ginger, Pineapple and lemon grass. 

His pineapple plant already had baby pineapple fruit!

She suggested doing the following; 

Select the best sample in the store.

For ginger rhizomes, check for a full jacket of skin and avoid dry shriveled 

Choose organic if available.

Check for missing bits 

Then look online for further hints. 

Storing seeds

Some seeds, particularly some flower seeds, are best sown immediately as their viability reduces with storage. These include

Astrantia

Aquilegia (but you can save some for spring)

Orlaya (if you can protect them)

Trilliums (but you need to clean the seeds)

However, for many species, sowing is best delayed until a more suitable time of the year, such as autumn or spring, so the harvested seed will need to be safely stored until sowing. Storing is also required if surplus seed has been collected.

Place dry seed in labelled paper packets or envelopes in an airtight container with some desiccant to remove excess moisture. Suitable materials include calcium chloride (sold in DIY stores for use in dehumidifiers) or silica gel.

Certain seed must not be allowed to dry out as they cannot then take up water necessary for germination. Examples are walnuts, oaks and magnolias. These seed can be stored in a plastic bag of damp vermiculite, sand, or a mix of moist coir and sand for several months 

It is said that storing in a refrigerator at 5°C (41°F) until required is the best way to do things.  Most seed will remain viable in this way for many years. But who has room for this if we are collecting quite a lot of seeds?

Orthodox and Recalcitrant Seeds

Seeds have been classified into two general groups; Orthodox and Recalcitrant (non-orthodox).

The first group, orthodox seeds, probably got their name because these seeds behave very much like the seeds that have been collected and stored for thousands of years. After collecting they can be dried and stored for a long time. This group makes up 80% of all seeds.

The second group of seeds were researched more recently and became known as recalcitrant (having an obstinately uncooperative attitude). In the early days these seeds seemed impossible to germinate, but now we know that they die when they dry out or are stored too cold.

Seed banks are set up to store orthodox seeds. The seeds are dried so that the moisture content is below 10% and for some species as low as 5%. Once they are this dry they can be safely frozen for a very long time.

Gardeners have learned about these storage methods and think it is best to mimic them. They collect seed and then place it in the freezer. If it is good enough for a seed bank it should be good for gardeners, but they forget one important step – drying the seed.

Freezing seed with a moisture content higher than 10% can kill the seed as ice crystals form.

Homeowners don’t have an easy way to measure moisture content and therefore they should not be freezing seed.

Who stores at 5c in a fridge?

Seed maturation is complex. Many orthodox seeds continue their maturing process after the seed is black and released from the mother plant. In some cases germinability increases only after the drying process starts.

Seed from chillis, tomatoes, eggplant, watermelon, bell peppers and cucumber have a high rate of germination when seeds are left in picked fruit for 14 days. This mimics

what happens in the wild. Fruits/seeds mature, fall to earth and experience cold gradually from late fall to winter. For this reason, it is not a good idea to store your seed in the fridge. Let it sit at room temperature and continue its maturation process. By late winter or spring it will be ready to germinate.

Freezing seed with a moisture content higher than 10% can kill the seed as ice crystals form.

Problems

Lack of collectable seed: Some plants are sterile and cannot set seed. Trying to collect seed from such plants will obviously be disappointing.

Others (e.g. holly) may carry male and female flowers on separate plants so male plants will never bear seed. Seed production can be exhausting for a plant so it is also not uncommon for seed production to be cyclical – some years will be good for harvesting, others bad 

it may simply be that weather conditions for that season were not favourable, perhaps due to a late frost or drought.

Poor viability (the length of time that seed stays alive and able to germinate): If seed is sown but fails to germinate, it suggests it was not viable. Seed viability depends on the condition of the seed when first stored, how long it is stored and what seed is being kept. A good propagation book should be consulted.

Cross Pollination

A hybrid plant is the offspring produced by cross-pollinating one specific cultivar with another different cultivar. This process of cross-pollination, rather than pollination between plants of the same cultivar, generally creates stronger, healthier, improved offspring, said to have ‘hybrid vigour’. Hybrids will be extremely variable. 

 
Flowers typically contain both male and female parts. Some plants produce two different kinds of flower – one with only female parts and another with only male parts. These single-sex flowers may be produced either both on the same plant, such as , such as hazel and courgette, or on entirely different plant, such as skimmia and holly.

	Cross Pollination.     Self Pollination
Definition	the transfer of pollen from the anther of a flower to the stigma of a flower of a different plant of the same species.	Self pollination is the transfer of pollen grains from the anther to the stigma of the same flower
Seen in	Insects: Apples, grapes, plums, pears, raspberries, courgettes blackberries, strawberries, runner beans, pumpkins, daffodils, tulips, lavender  Wind: grasses, catkins etc	Some legumes, cucumbers peppers,  Orchids, peas and sunflowers, wheat, barley, oats, rice, tomatoes, potatoes, apricots and peaches.
Transfer	Wind, insects, water, animals,	Shed pollen onto stigma.
Plant differences	Colourful petals, nector and scent, long stamens and pistils.	Smaller flowers.
Results	More variety in species. It allows for diversity in the species, as the genetic information of different plants are combined. However, it relies on the existence of pollinators that will travel from plant to plant.	More uniform progeny. Allows plant to be less resistant as a whole to disease. However, it does not need to expend energy on attracting pollinators and can spread beyond areas where suitable pollinators can be found.

VEGETATIVE PROPAGATION

Vegetative propagation uses leaves, stems, roots, or modified organs. It clones plants, producing plants identical to their parents. 

It includes division, layering, grafting, budding, and tissue culture techniques. 

Which technique you should choose depends on what type of plant you want to propagate, the purpose of your propagation, and how much time and effort you can put into the process. 

Cuttings

This is cutting the vegetative part of the plant (leaf, stem, and root) and then planting it again to regenerate the whole plant. Members had a go at planting the following; Stem cuttings, hardwood cuttings and softwood and green cuttings, using small pots of growing medium. 

This discussion only scratched the surface of vegetative propagation, and we will return to this subject at another discussion meeting in the future. 

Thank you all for coming!