Growing Herbs, Vegetables & Flowering Annuals from Seed

The following article on how to grow herbs, veggies and flowers from seed is republished with permission from Sustainable Gardening Australia. It's a helpful overview for those wanting to understand the steps involved in sowing, seed germination, raising seedlings and transplanting.

Growing from seed is fun and rewarding as well as being very cost effective. You can access a much broader variety of plants than those that are generally available as seedlings in nurseries. Commercial growers simply cannot afford to produce small volumes of a wide range plants profitably and so concentrate on the mass production of familiar and ‘safe’ options. So if you want to grow heritage plants or rare and unusual varieties, particularly of vegetables, then you need to grow from seed.

Nowadays it is relatively easy to obtain high quality seeds through nurseries or direct from seed companies through mail order. (Note that there are quarantine restrictions on seed coming into Australia from overseas).

Seed Provenance

One thing to consider when ordering seeds online is to identify the provenance or original source of those seeds. If say, you are purchasing seeds from a seed company in Queensland who produce their own seed, then potentially those seeds will have performed well in that environment. But will they necessarily perform as well in say, the foothills of the Victorian Alps? As a rule of thumb you should try to source seed from an area as close to your own growing conditions as possible. Some seed companies source seed from other growers so, if in doubt, check with the seed company.
An excellent way to source locally produced seed is to become part of the Seed Savers Network. This is an organisation that encourages members to grow, preserve, collect and exchange seed with other gardeners in the same area. For further information on the Seed Savers Network visit www.seedsavers.net

Seed Viability

When you are purchasing seed it is important to check the Use By date on the seed pack. Do not be tempted to buy cheap out-of-date seeds. Some of this older seed may germinate but it will probably give a disappointing result and the plants produced will be weak and not very good performers. Seed viability (its capacity to grow and develop) can be variable and, whilst some seed will germinate after being stored for hundreds of years, most seed will only last a season or two. In my experience, the smaller the seed the shorter its period of viability, so obtaining fresh seed is critical for a successful outcome.

A good reference for this is the ‘Seedsaver’s Handbook’, by Michel & Jude Fanton, the founders of the Australian Seedsavers Network. It lists the viability of many edible plants as well as describing in great detail how you can save your own seed. Importantly it also teaches you how to preserve true-to-type varieties by avoiding cross pollination with different varieties of the same plant. e.g. many plants in the cucurbit family (pumpkin, zucchini, marrow, cucumber, melons etc) must be prevented from cross pollinating with close varieties of their type. For example Pumpkin X will cross with a closely planted Pumpkin Y but their seeds will produce hybrids that may lack the desirable characteristics of either one or both of the parent plans.
A simple way to avoid this cross pollination is to only plant and grow one named variety of that plant each season. And check what your neighbour is growing on the other side of the garden fence as well.

Germination Rate

Some seed companies put a Germination Rate (GR) on the seed packet eg GR-85%. This means that for every 100 seeds, on average 85 will grow successfully. Seed packets generally contain a generous amount of seed, ample for any home gardener so the germination rate is probably not critical. But to avoid disappointment, it is a good idea to sow more than you want. For example, when sowing peas or beans you can put two seeds in every hole at the designated spacing. When the plants are about 15cm high, you can choose to remove the weaker of the plants where both seeds have germinated successfully. In other spots, only one seed may have germinated but the second seed will ensure that you won’t have any frustrating gaps.

Don’t give up on seeds too quickly. Most seeds start to pop up above soil level between 5 and 21 days after planting. But some seeds can take considerably longer so check the seed packet for accurate information.

Direct Sowing 

Whilst it can be advantageous to sow seed in seed trays, in order to control heat and water requirements for germination, some seed is best sown directly in garden beds. For example, legumes (peas and beans) as well as root vegetables do not transplant well and should always be sown where they are to grow.

One way to get around this is to use biodegradable pots e.g. toilet roll inserts, egg cartons or rolled up envelopes and sow individual seeds in these. Once conditions are right and the emergent seedlings are strong enough, soak the ‘pots’ well in water and then plant out in the garden. This method avoids disturbing the plant roots which is the reason so many seedlings fail at the transplant stage.

An early crop of summer beans, whether bush or climbing, can be produced by sowing seeds this way in a greenhouse, with the extra warmth tricking the seed into germinating. Once the seeds have germinated, they will grow on even when planted into cold weather.

Pre-Soaking of Seeds

One way to hasten germination, and also to see whether some particular seed is viable, is to pre-soak the seeds. Some sources recommend soaking seeds in water for a couple of hours before planting. Others recommend overnight soaking or even for a couple of days. In my experience, when germinating all types of beans, peas and zucchini (large seeds) seeds, soaking them in water or on moist kitchen paper for several days before planting is beneficial. For an extra ‘kick-along’ place the soaking seeds inside a clear sealed container and place on a warm windowsill. This will ensure that the germinating seedlings are supplied with moisture, light and heat.

Check seeds daily to make sure they are evenly moist and in case of any developing mould. If mould appears, wash seeds gently and returning seeds to the container with new, clean and moist paper will usually avert ongoing problems.

This method can also work well with carrot seed. Soak in tepid water for at least 2 days, changing water daily. Planting seed with a wooden skewer (a dibbler) can help – wet seed is difficult to place!
If any seeds fail to germinate when most others have, then they are not planted.

Planting Depth

When planting seeds they should be planted at a depth double their own size. Fine seed should be sprinkled lightly on the soil, or on the surface of the seedling mix, before a fine layer of soil or seed raising mix is cast across them. A sieve is handy to ensure no large soil particles inhibit germination of fine seed.

Mulch

Do not mulch newly sown seeds as weak seedlings may not be able to penetrate the mulch layer. In some cases a ‘scatter mulch’, e.g. fine straw, can be used to help retain soil surface moisture. A down side with any mulch is that it provides shelter for pests such as earwigs and millipedes that can decimate emerging seedlings over night.

Protection of Young Seedlings

As well as earwigs and millipedes, slugs and snails love tender young seedlings. To deter snails and slugs you could try sprinkling coffee grounds, collected from your friendly neighbourhood barista, around your seedlings. Or spread dried and crushed egg shells in the garden bed. Beer traps are reputedly delighted to drink themselves to death in beer traps.

Recycled plastic milk or soft drink bottles can be used as guards for emerging seedlings. Earwigs are trickier – try enticing them with squeezed grapefruit halves as little houses that they will harbour in. They also like to hide in crushed newspaper drizzled with fishy oil, stuffed inside plastic plant pots. Empty the ‘traps daily’ by disposing of the contents in a manner of your choosing!

Conditions for Germination

Seeds will generally germinate in response to a combination of natural stimuli. The most critical of these are moisture and temperature.

Moisture is generally easy for the home gardener to control with regular gentle watering (fine mist) and by choosing a free draining growing medium (in a seed tray or a garden bed) so that the seed does not become flooded. A simple soft-watering device can be made by using a heated metal skewer to poke holes in a soft drink bottle lid or a fine mist spray bottle.

Overwatering or water logged soil may lead to ‘damping off’, a fungal condition that leads to the collapse of young seedlings. Overcrowding of seedlings may also be a contributing factor, as can bad equipment hygiene. Always clean and sterilise containers before using, and always use fresh potting media (not recycled).

Temperature is a little harder to manage if you are not a commercial grower. The seeds of summer plants need night temperatures to be above 15°c for successful germination. A heat bed may be used to get summer seeds to germinate or they can be kept inside in a warm position until they have germinated. Other useful places to access heat are on top of an outdoor hot water system.

Winter vegetable seeds need night temperatures below 15°c to germinate. A prolonged summer will make it difficult to obtain these cold temperatures so any brief ‘cold snap’ should be taken advantage of. Once the germination process has started, a slight raise in temperature will not affect the plants growth.

Germination Period

Seeds generally germinate somewhere between 7 and 21 days after sowing. During this period it is important to keep the soil moist but not wet. If the soil dries out then the seeds will probably fail to germinate. The first two leaves of the seedling that appear are not ‘true’ leaves but are called cotyledons. They are most often different in appearance from the subsequent ‘true’ leaves. When the true leaves appear it is an indication that the seed has successfully germinated and post embryonic growth has commenced. If the true leaves take too long to appear the seed may become exhausted and fail to progress so it is vital to maintain the optimum germination conditions until this critical stage has passed.

Transplanting Seedlings

If the seeds are sown in seed trays, they should be transplanted when they are approximately 15cm in height when they should be able to resist transplant shock. Be careful not to damage the fragile roots when transplanting as this may cause the seedling to fail. Space or thin out seedlings to the appropriate distance as suggested on the packet so that they have ample room to grow. Water in gently after transplanting with a diluted seaweed emulsion. As they grow continue to provide regular water and a liquid fertiliser as per the seedlings’ needs.

Mail Order Seed Companies

Mail Order Seed Companies that supply heritage, open-pollinated or non-hybrid seeds are listed below. Some seeds may be treated with a fungicide so please read the description carefully, or contact the seed companies directly, if you are looking for untreated and organic seeds.

The Diggers Club: www.diggers.com.au
The Lost Seed: www.thelostseed.com.au
Green Patch Seeds: www.greenpatchseeds.com.au
Beautanicals Vegetable Seeds Australia: www.vegetable.seedsaustralia.com.au
Goodman Seeds: www.goodmanseeds.com.au
Eden Seeds: www.edenseeds.com.au
The Italian Gardener: www.theitaliangardener.com.au
New Gippsland Seeds and Bulbs: www.newgipps.com.au

[NOTE: See full list of Australian suppliers including those that supply certified organic seeds.]

Many new plant cultivars that have been developed over the past decade may be subject to Plant Breeders Rights (PBR). PBR is effectively a plant patent. You may propagate these plants for your own use but NOT for resale unless you pay a royalty to the PBR holder. If in doubt, check the original plant label or seed packet or look for the PBR symbol.