Beyond Marigolds – Growing Seeds Part 2

Once easy-to-grow seeds such as marigolds are mastered, it is time to tackle plants that are a little more challenging.

Starting seeds is an extremely rewarding activity and even trying to germinate some of the challenging seeds can be very successful if a little research is done to find out which techniques should be used.

If certain basic conditions are met, most annual and vegetable seeds do not require special treatment to achieve a high percentage of germination. The seed, which must be viable and mature, needs a proper balance of environmental conditions (moisture, temperature, light and air). Some more challenging seeds have natural inhibitors to germination and require special treatment. Such inhibitors include: a small dust-like size; a hard moisture-proof seed coat; a reluctance to germinate until maturity; a chemical that must be leached away; or specific requirements of light or darkness. These seeds may seem like they require extraordinary efforts to get them to grow, but these protections are adaptations which ensure germination at an appropriate time in the wild. Once they are known, then they can be overcome.

Seeds that are a challenge to both home gardeners and professional growers will often have poor or maybe even no germination unless a strict regimen is followed. Such seeds need extra attention to germinating or growing temperatures, moisture and light levels. Otherwise they loose their viability very fast after harvesting. Begonia seed will be dust-like, if the seed is not coated or pelleted, and will be very hard to sow. It also needs extra light during the day from January through March to grow to a size where it can be planted in the garden in early June. The shade loving annual, Browallia needs to be started extra early because it grows very slowly. Dahlberg daisy has irregular germination. Eustoma hates cool temperatures and must be germinated at 77 degrees F. (25 degrees C.).  Start this plant early and sow it directly into deep pots to accommodate an extensive tap root. Madagascar Periwinkle must be keep warm and in darkness until germination is complete. Do not overwater it or subject it to cool temperatures or it will sulk. Osteospermum must be kept cool and dry. Verbena usually has poor germination rates that could be as low as 30%. Use fresh seed that has been chilled for 1 week. Water the seeding pots and soil the day before sowing but do not water them after sowing because the seed is susceptible to rot if moisture levels are high. Cover the seeding containers with black plastic and keep them at 25 degrees C. Chill snapdragon seed for several days before sowing. Soak morning glory seed overnight to soften their coats. Germinate melampodium & mimulus at a cool 65 deg. F. (18 degrees C.). African marigolds should be covered after germination with an opaque material from 5 pm until 8 am for the first 2 weeks to simulate short daylength and produce better flowering. Nasturtium do not need any more than a starter fertilizer after they have been transplanted or else lots of foliage will be produced at the expense of flowers.

Seeds that are very small, such as fibrous begonia, petunia, coleus, dianthus or snapdragons, are often available as pelleted seed. This process coats each seed to make them easier to handle, and germinate faster. The extra cost of these seeds is worth it. Do not cover these seeds when sowing. Simply press them gently into the soil. Small seeds that are not pelleted can be mixed with horticultural sand and sown straight from the seed packet. Tip the packet on its edge and gently tap it with a pencil. The seeds will march down the packet and can be sown evenly spaced in a neat line.

Seeds with a hard seed coat that will not absorb moisture must go through a process of scarification to achieve good germination rates. The trick is to gently abrade the seed coat without damaging the interior seed parts. Depending on the size of the seed and the thickness of the seed coat, a knife, file or sandpaper can be used to scarify. Small seed can be soaked for 24 hours before sowing. This will soften the seed coat and shorten the time for needed for germination. Plant these seeds immediately after soaking. Commercial seed suppliers will use a scarifying machine or apply an acid to wear down the seed coat. One advantage of seeds with a hard seed coat is that they have a long storage life.

Stratification is a process where seeds are subjected to moisture and cool or cold conditions in order to get them to germinate. This is necessary for seeds that are immature when they are harvested. Many perennials and woody plants fall into this group. To get them to germinate, seeds are mixed with moist sphagnum moss or a seeding media and placed in a sealed, clear plastic bag. This is placed into either the refrigerator or freezer as instructed. After the recommended time has elapsed, the seeds can be sown into a seeding container. An alternative is to sow the seeds directly into a seeding container, cover it with a clear plastic bag, label and seal it and then place the whole thing into the refrigerator or freezer.

One of the most problematic diseases that attacks seedlings is called “damping-off.” This is a fungus disease that could be lurking in the soil or on seedcoats. The disease can even move from one seed container to another by hitching a ride through the water. Damping-off strikes very fast and without much warning. One day your newly germinating seedlings are fine and the next day some of them have toppled as if they were severed by a miniature chain saw. There are several tips to keep this disease under control. Use sterilized soil with good drainage to start your seedlings. Sow your seeds so that there is some space between each seed – do not overcrowd them. Make sure that there is good air circulation. You may have to set up a small fan to gently circulate the air around. Avoid overwatering your seedlings. Sowing seeds into rows will help reduce the chances that all of your seedlings will succumb to this disease. If the disease appears, a row or part of a row can be removed to stop the disease from spreading. Commercial fungicides for damping-off can be used to control this disease.

Once seedlings have grown to a stage where they have their first or second set of true leaves then they can be transplanted into their own pot or cell pack. The true leaves will normally be the ones just after the first two large food storage cotyledon leaves. Transplanting seedlings will give them more room to develop and will help to ensure that they have a strong root development.

Soils used for transplanting can be of a different recipe than the seeding media. It is less critical that this soil be of a fine consistency, but it must still be sterilized. When selecting the new growing container, remember that the smaller the volume of soil that annuals have to grow roots, the faster they will develop.

Many plants are available as a collection of mixed colours. Some colours are not as strong as the others. When transplanting seedlings into their own container select a variety of sizes to ensure that all colours are represented. This advice is contrary to the natural tendency of selecting the biggest and strongest seedlings. If this is done, then there is sometimes a risk of increasing the percentages of certain colours.

Before transplanting, fill your new containers with soil and moisten it. Also moisten your seedlings. Next choose a thin narrow tool to help untangle seedling roots. A pencil, ice pick, thin bamboo stake, chop stick, commercially manufactured dibble, or similar tool will work. Label your new container with the plant name and date.

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