Extension Master GardenerSM Volunteers of Buncombe County

garden planning

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

Kids Post: Planning your garden!

 

Do you have a vegetable garden? Do you know what you want to grow in your garden this year? Now is this time to choose! What do you like to eat? What would you like to try? Some crops are early, and you’ll get to eat them soon—like peas and radishes. Others will take more time, like tomatoes and pumpkins. Choose crops carefully and you’ll have food to eat all summer long!

Where to find ideas:

  • Seed catalogs (paper copies you may receive in the mail or online catalogs) are a great place to start—look at the pictures and find your favorites and maybe something new to try. Think about including some flowers to attract pollinators!
  • Black Mountain Library Sowing Circle is one community resource that has information and a seed-saving library you can visit during regular library hours.

How to decide!

Check on how much space your plants will take: how big is your garden plot or how much space do you have for container gardening? If you are gardening for the first time, pick a sunny spot that is easy to water. Test the soil now and fertilize and lime as directed!

  • Look at what you’d like to grow and figure how much ground or what size container will you need to grow this crop. Many crops need more than one plant for pollination and/or to produce enough to eat. Most vining plants need a lot of space or some kind of vertical support.
  • Make a map of where you’ll put each crop or container. Outdoors you can have fun doing some quick measurements—measure your shoe with a ruler or yardstick and then walk around your garden area to figure how may “feet” your garden area measures!

  • Make a map of your garden

Planning to plant

Can you put seeds directly in the garden? When? If you need to set out plants, do you have time and space to grow the plants to set out, or will you buy transplants?

  • If you want to start your own plants, read the seed-growing instructions and count back from the last frost date (you can use May 10 as a rough date for Buncombe County) to know when to plant for indoor starts.
  • Make a calendar and include when to plant your seeds both indoors (if you are starting your own plants) or outdoors.

Get ready, get set:

If you’ll be planting seeds, get them now! Many popular and new varieties sell out quickly and your seeds will be fine for the few weeks or months before you’ll plant them.

With transplants, though, be careful not to buy them too soon! Use your calendar to decide when to buy, not when you see plants for sale. You may end up with spindly, sickly, or overgrown plants if you buy them too early.

GROW!

Get an adult to help you figure out how to prepare your garden plot and/or containers. You may need to have your soil tested or buy potting soil. Make sure you follow directions on how close to plant seeds or plants and any other information about watering and fertilizing to be sure your crops will grow!

Look what we grew!

Article by Debbie Green, Extension Master GardenerSM Volunteer

For more on the Black Mountain Sowing Circle programs (FOR ADULTS):

Feb. 1, 10 to 11:30 AM, Free Gardening Workshops on Starting Seeds Indoors and How to Sharpen Pruning Tools. Black Mountain Library, Education Room

The seed library will provide free materials to get you started: seed starter soil, containers, and seeds to take home (limited quantities).  Bring your small pruning tools for sharpening. Presentations are in partnership with Black Mountain Blooms Seed Lending Library and Buncombe County Extension Master Gardener Volunteers.

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.**

For more on kids measuring in the garden:

http://www.njagsociety.org/uploads/1/7/0/5/17057112/you_are_the_ruler_lesson_plan_wbs.pdf

 

 

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

 

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

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