Extension Master GardenerSM Volunteers of Buncombe County

seeds

Soil Temperature: Know Before You Plant

This time of year I get anxious to plant my vegetable garden. I look out at the sunny days and think that I should be working in my plot; but sunny, warm days can be deceiving! I need to take a step back and consider other important environmental factors before I begin.

Soil temperature is probably the most critical indicator of when to plant. I have found out the hard way that seeds do not germinate—and transplants won’t grow—if I plant when the soil is too cold.  A soil thermometer is now an essential component in my gardening toolbox.

Soil Thermometer

Factors that affect soil temperature measurement:

Time of day

  • Soil temperatures tend to be coolest between 6 and 8 a.m. in the morning, so use temperatures at this time as a guide as for planting early season crops.
  • In the heat of summer, soil temperatures are highest between 3 and 5 p.m., so use temperatures at this time as a guide for planting late season crops.

Depth of thermometer

  • Take soil readings for seeds at a depth of 1 to 2 inches.
  • Take soil readings for transplants at a depth of 4 to 6 inches.

How to measure soil temperature:

  • Push the thermometer into the soil to the depth of planting.
  • In dense soil, you can use a screwdriver to make an initial hole to the right depth to avoid bending your thermometer.
  • Follow the directions that came with the thermometer as to how long to leave the thermometer in the soil to get an accurate reading.
  • Record the temperature and then move it to another part of the garden.
  • Record measurements from 3 to 4 different places in your planting plot.
  • Take soil temperatures daily for a few days and average the temperatures to be sure your soil is the right temperature for planting

Soil temperatures vary for each type of vegetable plant!

Greens_Billtacular_CC BY-NC-ND 2.0_Flickr
Arugala and mixed lettuces

A list of soil temperature data for some vegetable seeds’ germination:

  • Lettuce: minimum 32℉; optimum range 60 to 75℉
  • Peas: minimum 40℉; optimum range 65 to 75℉
  • Snap beans: minimum 60℉; optimum range 75 to 85℉
  • Pumpkins: minimum 60℉; optimum range 85 to 95 ℉

If you check the soil temperature rather than the air temperature or only the calendar date, you can increase your chance of your seeds sprouting and thriving!

Article by Bob Wardwell, Extension Master GardenerSM Volunteer

Interactive Soil Temperature Map for North Carolina: https://climate.ncsu.edu/map/

Soil Temperature Conditions for Vegetable Seed Germination:

https://sacmg.ucanr.edu/files/164220.pdf

Range of possible planting dates: https://content.ces.ncsu.edu/western-north-carolina-planting-calendar-for-annual-vegetables-fruits-and-herbs

The New Gardening Year: Can I Use Old Seeds?

What a wonderful time of year to be a gardener! The mailbox overflows with seed catalogs showcasing what is new for 2020. I also find myself looking at the 78 seed packets I already have—most great performers from past years—and see some were “packed for use in 2015” or even earlier!

Seed Packets

It’s time to decide if you need to buy new seeds; we can plant onions and peas outdoors as early as mid-February and if you grow your own transplants, you’ll want to start planning, too! For example, tomatoes will need 4 to 6 weeks before the last frost to grow to transplant size, so you’ll need to start them indoors early to mid-April here.

Seed longevity

Must I buy seeds packed for 2020 and throw away these old favorites? Not always—many seeds are viable for years. The Chicago Botanic Garden provides some general guidelines for vegetable seeds: http://my.chicagobotanic.org/wp-content/uploads/Seed-Viability-Chart.pdf

So, for example, if you have cucumber, pumpkin, or squash seed from 2014, you might be fine, but onion, leek, parsnip, or parsley seeds from 2018 may already be worthless!

Testing seed viability

If you want to test your own seeds, Ward Upham, Kansas State Master Gardener Coordinator, suggests the following quick and easy test for each type of seed you want to test:

Place 10 seeds on a paper towel moistened with warm water and cover with a second moistened towel. Roll up the towels and place inside a plastic bag with enough holes for air exchange but not so many that the towels dry quickly. Place the bag in a warm place such as the top of a refrigerator. Remoisten towels with warm water as needed. After the first week, check for germination. Remove sprouted seed and check again after another week. Add these numbers together to determine the percent germination.

Testing Seed Viability and Germination

Planting old seed

If your old seed is still viable, you can simply plant extra seed in anticipation of lower germination rates.

Storing seed

The best places to store your seed are where it is cool and dark, such as the refrigerator or a cold basement. If you save seed from your garden, be sure the seeds are dry before you store them. For purchased seeds, keeping them with their original packets allows you to quickly determine the contents. Seal seeds in an airtight container, such as a canning jar, to prevent moisture.

Article by Bob Wardwell, Extension Master GardenerSM Volunteer

For more information:

Vegetable gardening planting times: https://extensiongardener.ces.ncsu.edu/wp-content/uploads/2016/07/NC-Vegetable-Planting-Guide-1.pdf?fwd=no

**Note: Planting times for Western North Carolina Mountains are in purple and times to harvest from seed are indicated in the left-hand column. Those with an “*” should be started indoors rather direct seeded in the garden.**

Tips for growing plants from seed:

https://content.ces.ncsu.edu/extension-gardener-handbook/13-propagation#section_heading_5129

 

What to Know Before You Buy That Grass Seed for Your Lawn

Is your lawn in need of replacing or repairing? Here in Western North Carolina, we recommend using cool season grasses—and August 15 to September 15 is the best time to plant!

Grass Seed

Seeding after these dates increases the chance of failure caused by winter injury. If you don’t accomplish seeding cool-season grasses in the fall, your best alternative is mid-February to early March.

Recommended grass species:

Tall fescue, Kentucky bluegrass, perennial ryegrass, and fine fescues—such as creeping red, chewings, and hard fescue—are cool-season perennial grasses used for lawns in the mountains. These grasses perform best in spring and fall and have a tendency to show signs of stress in the summer. Recommended rates of seeding for these grasses for new lawns/reseeding are between 1.5 to 2 pounds of seed per thousand square feet for Kentucky bluegrass and perennial ryegrass and 6 pounds per thousand square feet for tall fescue.

 Understanding the label:

Grass Seed Label

Much like a label on pesticides you purchase, the label on a bag of grass seed provides invaluable information about:

  • The seed variety or varieties: In the example given, ‘Grand Slam GLR’ is the variety of perennial ryegrass, ‘Midnight’, ‘Everest’ and ‘Bewitched’ are the varieties of Kentucky bluegrass, and ‘Radar’ is the variety of chewings fescue.
  • Purity: Purity is the percent by weight of each seed component (variety or species) in a mixture and is a measure of “seed quantity.” In the example given, 24.06% is pure ‘Midnight’ Kentucky bluegrass, 19.93% is pure ‘Radar’ chewings fescue, 19.73% is pure ‘Grand Slam GLR’ perennial ryegrass, 19.71% is pure ‘Everest’ Kentucky bluegrass, and 15.63% is pure ‘Bewitched’ Kentucky bluegrass.
  • Germination percentage: Germination is expressed on the seed label as the percentage of pure seed that is capable of growth. Germination declines with age of the seed and therefore seed older than 9 months to 1 year may be less viable than fresh seed. The date when the seed was tested for germination is included on the analysis tag as an indication of freshness and to protect the buyer. Purchase only the freshest seed of the highest purity and germination.
  • Date: The date when the seed was officially tested. It is January (01) 2019, in this example.
  • Other crop seed:Crop seed content is the percent by weight of all seeds identified in the bag that are grown as an “agricultural crop.” These must be specified by name if they exceed 5% of the weight of the seed bag. Look for the lowest possible crop seed content. In this example it is 0.08%.
  • Weed seed: The percent by weight of all seeds in the container that have not been identified as pure seed. In the example, this value is 0.0%.
  • Noxious weeds: Expressed on the label as the number per pound or per ounce found in the seed lot. Weeds classified as noxious can vary by state and are difficult to manage even with proper chemical and cultural practices. In this example, none are specified, which is the best!
  • Inert matter: The percent by weight of all material in the seed container that will not grow. This value should be as low as possible because seed cost is based on bag weight—inert material contributes to bag weight but does not contribute any value in term of seed quality or purity. In this example, it is 0.86%.

Know before you buy!

Reading the label will help ensure that you not only get the best value on the seed you buy but that you will minimize the number of unwanted weeds in your lawn!

Article by Bob Wardwell, Extension Master GardenerSM Volunteer

 For More Information:

Replacing your lawn:

https://www.buncombemastergardener.org/lawn-replacement-lawn-new/

Carolina Lawns: A Guide to Maintaining Quality Turf in the Landscape https://content.ces.ncsu.edu/carolina-lawns

 

 

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Buncombe County Extension Office
49 Mount Carmel Road
Asheville, NC 28806
Helpline 828-255-5522

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