Starting summer vegetables from seed
Written for the Davis Enterprise, January 28, 2010
We've had a business web site for over a decade now. That's a pretty long time in internet history, so we've crept up on search engines to the point that we get 30 - 50,000 hits a week. My server thoughtfully provides lots of statistics about what people are looking for, where they're from, and which pages they're looking at.
Some of these stats are curious. The highest number of foreign web site visitors, week in and week out, is from France. China, the UK, and Russia are always high on the list. But why are hits from North Korea eighth on the list this week?!? The 600 to 700 people each week who find us by searching for "shades of purple" may be happy with the article with that title that I wrote for the Enterprise about purple flowers (June, 2006). More likely they were looking for the album of the same name by the Norwegian pop duo M2M (#1 in Norway in 2000!). Since the Christian Science Monitor linked to my picture of Aspidistra in an article about low-light house plants in 2008, nearly 2500 people have clicked on it.
In spite of seasonal ups and downs about various timely topics such as frost protection or fruit trees, the search inquiries that consistently have the highest percentage of hits have to do with planting seeds. An article I wrote for the Enterprise in April 2005, Seeds That Are Easy To Grow, is always in the top 5 pages viewed. The exact phrase "fast growing seeds" was 5% of the search inquiries last week, far above any other single inquiry. "Fast germinating plants ... easy to grow seeds ... easy seeds for kids ... how to plant seeds ... ." and the like added up to 12% of search phrases.
Ok, I get the message! You want to know about seeds! As it happens, February is a great time to start planting seeds for summer vegetables and flowers.
Garden centers will have lots of seedlings of tomatoes, peppers, and eggplant at the proper planting time. But there may be unusual varieties you wish to grow. Starting seeds indoors can be a fun project. You may wish to save a little money, or make sure that your seedlings are organically grown.
But the indoor environment is not ideal for vegetable plants.
o Low light and lack of air movement cause plants to "stretch" and become leggy. There is the risk of attack by seedling diseases.
o If you start your seeds too far ahead of outdoor-planting weather, they become very tall and undergo transplant shock when you finally move them out.
Given these limitations, the following guidelines will help you succeed:
When to plant
o Start tomato seeds 6 to 8 weeks ahead of your outdoor planting time. We plant outside in late April or May here. Tomato seedlings sprout in about a week and grow very quickly.
o Start pepper and eggplant seeds 10 to 12 weeks ahead of your outdoor planting time. We plant them outside in May here. These seeds sprout in 1 to 2 weeks and grow rather slowly.
Planting by the calendar?
Tomatoes grow faster, but can be planted out earlier. Peppers and eggplant grow slower, and require warmer soil outdoors. So February is the ideal month to start all of them here. Just be aware that you will hold your pepper and eggplant seedlings a few weeks longer than your tomatoes before putting them in the ground. March is ok; April is too late from seed.
What to use
You can make your own seedling mix quite easily. A good blend will retain moisture, but not stay soggy, and will NOT contain ingredients that might encourage fungus diseases. Shown here, we used 2 parts peat moss to 1 part each perlite and pumice. Containers are two to four inches diameter, sufficient to hold the seedling up to three to four inches height. The peat pots (brown pot, center) have an advantage that the seedling can be planted in them directly in the soil without disturbing the roots, and the pot simply disintegrates.
o Start seeds in a soil mix that is naturally sterile. Seedling mixes usually contain materials such as peat moss, sand, perlite, vermiculite, or pumice. Peat moss holds moisture. The others are coarse, low-nutrient media that drain quickly. All are basically sterile, providing little sustenance for fungus and bacteria.
o The mixes should not contain garden soil, compost, wood shavings, or fertilizer. So you don't use a regular potting soil to start seeds, as most potting soils contain compost and fertilizer, and some contain wood shavings.
No fertilizer? Not yet. Seeds don't need food while they are sprouting: the cotyledons (the first two leaf-like structures that sprout, usually called cotyledon leaves) contain all the nutrients the young seedling requires. Fertilizer in the soil mix encourages seedling diseases.
Any small pot or tray will work fine as long as it has drain holes. Small nursery pots, recycled nursery 6-packs, or even yogurt containers or small milk cartons are all fine. Wash them with soap and warm water. If you have used them for seedlings before, a quick dip in a bleach solution helps prevent fungus (one glug of bleach in a gallon or so of water).
The soil ingredients should be blended thoroughly. Always wear gloves when working with potting soils, as some of the ingredients can cause minor skin irritation.
What are these?
Peat moss is the decayed remainder of sphagnum peat, a moss which grows in very acidic bogs. It is very lightweight, and holds up to 20 times its weight in moisture, releasing it slowly to the plant. You should hydrate peat moss before using it by pouring some water into the bag. Most American peat moss comes from Canada, which has about 270 million acres of peatlands.
Perlite is a volcanic glass that has a high water content. When it is heated, the water vaporizes and escapes, and the perlite expands by more than ten times, leaving a rock with lots of air pockets. It is lightweight and enhances drainage.
Pumice is just solidified frothy lava rock found near volcanoes that have erupted violently. It is heavier than perlite, so it helps to anchor the plant, and also enhances drainage.
How to plant
o Fill the pot nearly to the top with soil mix.
o Don't plant too many seeds close together. Seedling fungus moves rapidly from one soft stem to another. Plant 2 to 3 seeds in each single pot or cell.
o Cover with a fine layer of soil mix. Water gently with a hand-held sprayer set to a coarse spray.
o Label your pots!
The seedling trays don't need to be covered, although that will speed germination by keeping temperatures and humidity a bit higher. Remove any cover as soon as you see the seedlings.
Where to grow them
Place the seed pots in the brightest natural light in your house. A window facing south is ideal; east is second-best. You can put them under fluorescent lights or grow lights, but those light sources need to be very close (12 inches or so) to the plants.
Seedling care
o Water gently. The stream from a hose or water can is likely to wash the seedlings out. A small spray bottle is more effective.
o As soon as they sprout, move the seedlings outside during the day and back in at night. This is very important! Air movement causes plants to move and release an internal hormone that thickens the stem. Natural sunlight is better for plant growth than indoor light. But the night temperatures are still too cold for the plants. So the daily shuttle in and out, hassle that it may be, is the key to getting sturdy seedlings.
Interestingly, it is vibration of the plants that triggers the hormone which thickens the stems. So gentle air movement indoors, such as from a small fan, or some form of vibration of the pots, might do the trick. Or gently shake the seedling tray every time you walk by.
Once they have a set of true leaves (the set that forms second, after the cotyledon leaves), they will want to be fed. Regular house plant fertilizer at half strength every 2nd or 3rd watering will work. One popular brand has you fertilize every time you water, which is also fine. Organic fertilizer such as fish emulsion is fine, but odoriferous (your cats will appreciate it; you might not).
If the seedlings are growing fast and outdoor planting is still a few weeks away, you may wish to transplant them into larger pots. For this next stage, any good potting soil will do. They can be left outside on warmer nights without harm.
When to plant in the ground
Plant tomatoes outside when the night temperatures are consistently 50 to 55 degrees F, or the soil temperature measured with a soil thermometer is 60 F. Plant peppers and eggplants outside when the night temperatures are consistently 55 to 60 F, or the soil temperature is 70 F.
Other summer vegetables
Most of the other vegetables we grow in warm weather sprout and grow much more quickly from seed, as does the popular herb basil. So these are planted much closer to outdoor planting time, usually in March or early April:
o Cucumbers
o Melons
o Pumpkins
o Squash
o Beans
o Okra
o Sunflowers
These large-seeded types can be planted directly in warm, loose soil. If you want to start them in pots, plant 2 - 3 seeds each in small individual pots. They will sprout in just a few days and be ready to plant out in a couple of weeks. Don't keep them in pots too long or they will be stunted.
Vegetables grown for their roots should be planted directly where they are to grow, as transplanting damages or stunts the roots. These prefer milder weather, so try to get them planted by April:
o Beets
o Carrots (sprout very slowly)
o Radishes (sprout very quickly!)
Potatoes are grown from roots (tubers) which are cut, left to sit for a day or so, and then planted directly in the ground in warm, loose soil. Buy certified disease-free potatoes anytime February through early fall.
What about basil?
Basil has small seed but is very easy to grow, sprouting in just a few days. Sprinkle the seed onto soil in a small pot and gently press it into the soil, then cover with a very fine layer of soil. Once the seedlings are an inch or so tall, you can plant them out in the ground.
A garden without flowers? Of course not.
Be sure to start some easy summer flowers: sunflowers, nasturtiums and cosmos are all quick and easy from seed. While you could seed them directly in the garden, they are also readily started in containers, along with your summer vegetables, anytime February through May.
Don't fret if your seedlings aren't as deep green and robust as the ones you see in garden centers. Properly "hardened off" (prepared for outdoor planting by gradually acclimating them to outdoor sunlight and temperatures), and given a little TLC with watering and fertilizing once they're in the ground, your homegrown seedlings will catch up quickly.
For a printable version of this article, click here (pdf)
© 2010 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616
www.redwoodbarn.com
Feel free to copy and distribute this article with attribution to this author.
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