Seed starting basics

Dolichos lab lab 'Ruby Moon' planted 1 April 01

Arrow points to seed coat still clinging to cotyledons (the rounded pair of things at the top of the stems below the leaves). Seedlings get their initial growing energy from the cotyledons, which are the bulk of the seed mass. These soon start shriveling as the leaves take over the task of producing food.

Note the short stout stems.
I've kept greenhouse temperatures in the 70's during the day for the most part, and in the low to mid 50's at night.

Causes of spindly weak seedlings:

Temperatures too high--either day or night or both.

Not enough light. Seedlings will stretch toward the light. I keep seedlings under fluorescent lights about 16 hours a day. The lights are just a couple of inches above the plants.

Not enough air movement. You should have a fan running gently near the plants at all times. This helps them grow stocky and also prevents damping off fungus.
Also, brushing your plant tops gently with your fingers for a couple of minutes a day will help them grow stocky.

Seeds planted too deep. Seeds have a limited amount of energy (in the cotyledons) to push themselves up through the soil.

Not enough food. Once you see leaves, you should be giving the plants weak solutions of fertilizer (I use fish & kelp emulsion).


Ipomoea purpurea 'Grandpa Otts' planted 1 Apr 01

Again notice short stocky strong stems. The leaves are a darker green in real life. The arrow points to another seed coat attached to a seed leaf.


I have raised the lamp for this photo. Normally the fluorescent bulbs are just a couple of inches away from the plant tops. As they grow, I adjust the light.

This setup is just some ventilated plastic shelving (from Home Depot) with a 4 foot shop light suspended from the bottom of the shelf above with wire hooks and the chain that comes with the light fixture.

Above is a flat I just planted today (various types of sweet basil, some pole beans, and melon.

When I plant small seeds (such as basil), I generally use a 4" pot to start. I fill it with good potting soil, water it with warm water, rough up the soil surface a bit, then sprinkle the seeds over the entire surface. I press the soil surface down slightly to set the seeds and then add a layer of perlite on top. The perlite drains very well and dries quickly, thus keeping fungus from forming at the soil surface. Very soon after the seeds sprout above the surface, I prick them out with a fork and plant the very tiny plants using bent-end tweezers into their own cells or pots.

Larger seeds (and tomato seeds) are usually planted separately in their own small "cell" in a flat or a 4" pot to begin with. They are planted a a depth that is about three times their thickness.

I plant bean and pea seeds with the "eye" down, because that is where the root emerges.

I plant cucumber, melon and tomato seeds so that the thinnest part is on top and bottom and the flattest part of the seed is on either side. That is so when the seed sprouts, it can easily push up through the soil. (Think of a table knife--It is much easier to cut through something sideways than to lay the knife flat and try to push through.)

Larger seeds with heavy seed coats I always put in a small bowl and pour hot tap water over them then let them soak overnight before planting.

Often I will presprout seeds between the folds of a wet (but not dripping) paper towel that I then place in a zip lock plastic bag. I check the seeds daily (or more often); as soon as I see a root sprouting, I plant them in potting mix mulched with perlite at above.

The fully planted perlite-mulched and watered flat is then covered with a plastic dome made for that purpose. It is placed on a wire frame suspended over a heat mat specially made for starting plants. Notice how humid it is. As soon as the seeds sprout, I prop up the edge of the dome to get good air circulation in the flat.

My heat mat has no thermostat (I need to add one), so sometimes the soil gets pretty hot. One year that I was actually measuring the temperature, it was 100 degrees Fahrenheit, and seeds such as cucumbers and zucchini sprouted above the soil surface overnight! 85 degrees is a better temperature to aim for, I think.

Here is a Cucumber 'Glacier' planted 1 Apr 01

The seedling in back is just pulling the last of its seed leaves out of the soil.

Notice that the seed leaves (cotyledon) are usually not like the true leaves. Cucumber adult/true leaves have multiple points and are usually fuzzy, not smooth.

Notice the seed leaves of the Ipomoea purpurea 'Grandpa Otts'. They are an interesting shape. The adult/true leaves of this Morning Glory plant are heart-shaped. Within the next couple of days, these plants should be potted up into 4" pots from these small cells.
Below is what this plant's flower looked like in my garden last year. Flowers only last one day and usually close and wither around noon. This particular plant often opened 20+ flowers a day!

I'm sorry that I don't have tomatoes sprouting just yet. I just planted them today! My earlier tomato plants are far past the seedling stage at this point. I'll get some images of the upcoming seedlings as soon as I can.

If you have more questions (this draft page is far from complete!), just email me using this link. I hope this has helped you. Please help me by letting me know what you would like to see in a seed starting feature for the website. Thanks!





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