DOWN IN THE DIRT: The basics of getting your seeds in the soil
This is what you’ve been waiting for through all the dreary, cold months of Idaho’s winter. Now, finally, it will be you, the seeds and the soil. Following is a discussion of the basic considerations for successful sowing: soil preparation, seed preparation, seed planting techniques, watering and thinning.
Preparing the Soil:
Soil tilth: A friable (crumbly, loose), well-prepared soil is a must for getting your seeds off to a good start. Breaking up the soil and creating a loose, soft base for the seeds is very important. Here are three important things to remember as you prepare to do this:
- Do not work soil that is wet. If you can take a handful of dirt and squeeze it into a ball that holds its shape when tapped with your finger the soil is too wet to be worked. Digging in or walking on soil at this point causes harmful compacting which limits the soil’s ability to hold water and oxygen. Wait a few days then try the soil test again.
- Likewise, if the soil is very dry working it breaks it into such tiny particles that it can become too compacted and crusty when it is watered. If your soil is dusty dry give it a thorough watering and then wait a day or two before doing the soil squeeze test to check for workability.
- If your soil is deficient in organic matter add grass clippings, compost and/or well-aged manure to the surface before working the soil. That will insure that the organic matter gets incorporated into the soil and can begin breaking down. Additions of organic matter ( including turning under your fall cover crop) should be made at least 2-3 weeks before planting.
You can break up the soil using either a spade, a garden fork or a power tiller. The hand tools will be better for your soil in the long run because they will not pulverize the soil as thoroughly as a tiller will. After breaking up the soil rake it to as smooth and finely worked a surface as possible, discarding any rocks or large sticks, twigs, weeds, etc.
Soil temperature: Soil temperature is an important factor for germinating success. Almost all seeds have a temperature range in which they will reliably sprout. Seeds planted when the soil is too cold or too hot will yield inconsistent results, wasting your seeds, time and money. The most reliable way to determine soil temperature is to use a soil or compost thermometer but it is also possible to plant by broad seasonal categories; early spring, mid-spring, and late spring. (More about this in the seed section.) You can positively affect soil temperature with several different techniques:
- Raised beds will generally result in earlier soil warm-up, especially those that are mounded, not framed. (An exception to this is in areas of consistently high winds.)
- Covering the area to be planted with black plastic or IRT plastic mulch will add significant warmth to the soil. The plastic would then be removed or the seeds and seedlings would be planted through holes in the plastic.
- Setting up a Wall ‘o Water a few days in advance will warm the ground where a seedling is to be planted.
- To cool the soil shade cloth or lathe boards can be suspended over the area to be planted.
Soil moisture: Once the seeds are planted maintaining proper soil moisture levels becomes critical. Allowing the soil to dry out just as a seed is about to germinate will often kill the seed. (Similarly, if the soil is kept too wet the seeds will rot before they have a chance to sprout.) There are several techniques that help keep moisture levels consistent during germination:
Preparing the Seeds
- Cover the planted area with a piece of wood or burlap to reduce evaporation and check daily for signs of sprouting. Remove the cover as soon as seeds begin sprouting.
- Sprinkle a light covering of coarse straw over the planted area and water it gently. This will shade the area sufficiently to reduce evaporation without inhibiting germination.
- Mist the planted area daily with a fine mist nozzle during dry periods. On very warm days it might require two applications. Once seeds are up and well-established watering should become less frequent and deeper.
- If using a drip irrigation system run it often enough to keep the surface damp but not soggy until sprouts have appeared.
As I have mentioned before, good seeds are more than worth the investment. No matter how careful you are with all the other aspects of seed starting you will not be satisfied with the results unless you have good seeds. Once you have your seeds and seedlings, it is time to separate them into groups depending on when they should be sown or transplanted:
Don’t get married to a particular date for planting a specific plant, like peas on St. Patrick’s Day. Using only calendar guidelines for planting is a risky practice in this part of Idaho because of the variability of the weather. One year in late March you might have 6” of snow on the ground while the next you could be experiencing record high temperatures. Look at the weather trends and month-long forecasts as you assess how the weather is progressing in a given spring - and be prepared to protect plants if we have a spate of colder-than-usual weather. Don’t forget the importance of hardening off any seedlings you have grown indoors before planting them outside.
- Early spring (soil temp 40-45+ degrees F): peas, onions, dill, radishes, turnips, lettuce, spinach, red orach
- Mid-spring(50-55+ degrees F): carrots, beets, cabbage family, fennel, cilantro, leeks, parsnips, potatoes, hardy annual flowers, chard
- Late spring (70+degrees F, after last danger of frost): beans, tomatoes, tender annuals, corn, eggplant, peppers, squash, cucumbers
Here are three techniques which can be used to hasten the germination or improve the vigor of your seeds:
- Presoaking softens the seed coats of hard seeds like peas, carrots and parsley. Soak seed for 2-3 hours in hot-to-the-touch water, then drain and plant immediately. Small seeds may be mixed with a dry substance like sand to prevent clumping.
- Pre-sprouting seeds ensures a uniform results because only seeds which have germinated are planted. To pre-sprout, roll the seeds in a damp paper towel or cloth inside an open plastic bag placed in a warm location. Check for signs of sprouting every day and plant gently as soon as they sprout.
- Inoculating pea and bean seeds adds helpful rhizobium bacteria, improving both the soil and the crop. Inoculant is available at most garden centers.
Sowing the Seeds
Now the seeds and the soil are ready and you are going to actually get down in the dirt. The rule of thumb for spring planting is that the seed should be covered with 3 times their diameter in soil ( a little deeper for summer plantings). Firming the soil to optimize seed/soil contact is especially important. A gentle initial watering will settle the seeds into the soil and can be repeated as indicated by the weather conditions. Spacing requirements are indicated on almost all seed packets and thinning will achieve what seeding accuracy didn’t. There are a number of homemade tools which can simplify the spacing task.
Now you need to decide which seeding technique you will use:
Once the seeding is completed the seeded area should be gently but thoroughly watered. Using a fine spray nozzle or watering can minimizes the possibility of washing the seeds out of the soil. The soil in spring is usually sufficiently cool and moist but if there is a dry spell supplemental water can be critical. Floating row cover can also help retain soil moisture while waiting for germination. (See Soil moisture, above, for additional techniques.) Water conditions need to be carefully monitored once seedlings have emerged until they have established sufficiently deep root systems.
Once seedlings emerge it is important to ensure that they have enough room to grow. Thin seedlings early and often until you have achieved the recommended planting distance. Some thinned plants, if carefully removed, can be transplanted into new spaces. Others, like lettuce and beets, can be harvested for eating even when quite small.
Beds need to be carefully prepared for seedling transplants, too. The issue of good soil/root contact is important and is optimized by good soil prep. Be sure to warm up soil as necessary before transplanting if the soil temp is too cool. Water your seedlings thoroughly before transplanting. Water the generously sized hole to settle the soil before setting in the seedling. Gently pack the soil around the plant to eliminate air pockets. Water again immediately with manure tea or seaweed extract. Protect seedlings from strong winds and extremes of heat, cold and drought. Except for tomatoes, seedlings should be set out at the same depth which they were growing in their containers. Tomatoes can be set into the soil up to their first set of leaves.
Take advantage of early space in the garden for quick maturing or shade-loving plants that will later be taken up or shaded by the spread of large plants. Plant radish seeds in the same row with carrots or lettuce. When the radishes mature and are pulled, thin the carrots. Or, plant lettuce in between the broccoli and cabbages. By the time the brassicas have grown together the lettuce will be finished. Plant bunching onions similarly and pick them as they mature leaving the space for the other plants by the time they have grown large enough to need it. Do a little research on companion planting before deciding on planting partners.
A fun activity for kids is to make home-made seed tapes for small, difficult-to-sow seeds.
· Prepare seed bed, place seed tape and cover with soil. Water lightly.
- Use 3 - 4’ sections of sturdy toilet paper or paper towels
- Check seed packets for correct seed spacing
- Mix 1 T. cornstarch or flour in 1C. cold water and cook over medium heat, stirring constantly, until translucent and gel-like. Let cool to room temperature but don't allow to stiffen.
- Mix seeds and cornstarch together and put in a plastic sandwich bag. Snip off small corner of bag and squeeze dots of the mixture onto the paper strips at proper intervals.
- Let tapes dry then label and roll up. Store in plastic bag until ready to use.
FURTHER READING / RESOURCES
- The New Seed-Starters Handbook, Nancy Bubel, Rodale Press
- Your Organic Garden, Jeff Cox, Rodale Press
- Growing Fruits and Vegetables Organically, Nick and Bradley, Rodale Press
- Crockett’s Victory Garden, James Crockett, Little, Brown and Co.
National Gardening Association Q & A Library - lots of great information
The Garden Gate -directory for internet gardening sites
The Weekend Gardener - individual plant guide, seasonal planning guide
Web Gardening Links - a zillion links!
For more information about the Idaho Falls Community Garden
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