Planting Tomatoes When the Soil is Too Cold

When planting seeds or transplants it is important for the backyard grower, community gardener or urban farmer to keep track of soil temperatures, as the soil is where the seed will germinate and where the roots are located.  It is not uncommon to have a large difference in soil temperature in relation to air temperature, especially early in the season.  A grower can get fooled into thinking the time is right for planting based on a warm sunny spring day when the soil temperatures are not actually at the point ready to plant.  I see tomatoes planted each year in April or early May that have been planted too early.

When planted before the soil warms up, phosphorus is not able to be taken up by the plant, even if enough phosphorus is present in the soil.  This manifests in a purple discoloration of the tomato leaves, especially the older leaves near the bottom of the plant.


The purple coloration is from anthocyanin, the same pigment that gives blueberries its color.  Phosphorus is a critical macro-nutrient that assists seedling growth and vigor.  These tomato plants are at risk of further disease or insect damage due to being stressed from nutrient deficiency.

To remedy this, you need to deliver phosphorus to the plant.  The best way would be to use a foliar feeding of a water soluble fertilizer containing phosphorus applied to the leaves, top and bottom.  This should be done early in the morning before the tomatoes stomata close. (the pores on the leaves).  Once the soil warms up the tomato will start to take up phosphorus if enough nutrient is present.  You may need to foliar feed until this occurs.

It is important for the backyard grower, community gardener and urban farmer to monitor soil temperatures to ensure that seeds and transplants go into the ground at the correct time to maximize production success and minimize potential problems.

Ohio State maintains a website with soil temperatures at all of the OARDC stations.  Click here for the link to check soil temperature in your part of Ohio.


Spring Gardening Classes at Bexley Community Gardens in May

There will be two classes held in partnership with City of Bexley Community Gardens to assist the backyard grower, community gardener and urban farmer.
Bring your friends and your questions to these informational garden walks to discuss how to improve soil health in your plot as well as talk strategies to combat the weeds that can drive you crazy.

Classes are free and open to the public.

Using Cover Crops for Weed Control in Spring

Cover Crops are a valuable tool in the toolbox of the backyard grower, community gardener and urban farmer.  I planted a mix of cover crop species last fall in my community garden plot to keep the soil alive over the winter, prevent erosion and increase soil organic matter.

Winter rye, forage radish, hairy vetch and crimson clover blend

This species mix, especially the winter rye component, can be challenging to manage in the spring depending on when the soil is worked.  The winter rye will die from mowing or crimping when it is going to seed and nearing maturity, but when tilled young, some of the grass will continue to grow.

The city tilled the garden in late March, some of the cover crops persisted and will continue to grow without further tillage or herbicide application.

The majority of my plot will be used for summer vegetables.  I do not want to leave the ground bare until that point as the cover crops will continue to grow in spaces and weeds will fill in the rest.  I would also lose organic matter and fertility from spring rains.

I rototilled over half of the plot to create a seed bed about 10 days after initial tillage.  This will kill most of the remaining over-wintered cover crops and created a seed bed for planting.

I followed up with a planting of Buckwheat.  Buckwheat is a versatile cover crop that tolerates poor soils, rapidly germinates, weed suppresses, attracts pollinators and when mowed, will rapidly break down prior to the next planted crop.



I will let the Buckwheat grow until mid-May.  Then I will mow the space which will kill both the cover crop and any annual weed that germinates within the Buckwheat planting.  It will also weaken any perennial weed that is growing.  I will let the residue decompose for a few days and then till and apply plasti-culture mulch in the pathways prior to summer vegetable planting.


2019 Spring Planting Update for Central Ohio

Our first sunny days in the 50’s and 60’s are here and many backyard growers, community gardeners and urban farmers are looking to get outside to start spring planting.  One important step in this process is to make sure the seed that you are using will have decent germination rates to ensure that you do not start with a crop failure at the beginning.  Check this post on Growing Franklin for vegetable seed viability times. 

Have you soil tested your vegetable garden recently? Making sure that you have enough nutrition present to grow your vegetables is another important step in making sure that you have a productive season.  Contact our office if you wish to purchase a soil test as well as get instructions on how to soil sample.  You may be able to get a free soil test kit from our office if you grow in a community garden or urban farm in the City of Columbus or provide food for those who do live in City limits. (LINK)

The National Weather Service Climate Prediction center has their three month projection for April-May-June for temperature and precipitation.  (LINK)

The three month precipitation prediction calls for a greater than normal chance for increased precipitation.


The three month temperature projection calls for a greater chance of warmer than normal conditions.

One very important variable to monitor is soil temperatures.  Since seeds are in primary contact with soil and need that seed-soil contact to germinate, it is more important to monitor soil temperature than air temperature.  Certain seed varieties will need certain temperatures based on what family of vegetable they are in.  Most spring vegetables germinate reliably in cooler soil than summer vegetables.

Currently soil temperatures as monitored by the Columbus Station (Waterman Farm) of the OARDC Weather System are around 40 degrees F at 5 cm and 10 cm soil depth.  (LINK) If you garden in a raised bed, you may have warmer soil than a level garden plot.  This may allow earlier planting than normal.

Make sure that you do not work the soil via tillage if it is too wet, especially with the heavy clay soils common in central Ohio.  This could create a poor growing condition for the entire season if large clumps of compacted soil are created when tilling wet soil.

This community garden was mowed last fall with the residue left on top of the soil. A seed bed was created via tillage a few days ago when the soil was at the right moisture level.

If you have started transplants under grow lights in a seed station, it may be time to transplant them into individual cells.  Check out this video on Growing Franklin that will show how to divide and transplant seedlings into cell packs. 

Good choices for spring vegetables to direct seed into the garden once your soil is above 40 degrees F:

  • Spinach
  • Radish
  • Carrots
  • Lettuce
  • Peas
  • Swiss Chard
  • Cabbage family

Seed potatoes can be planted later this week if the soil is not too wet to work.  If you wish to plant onions but are unsure if you should use seeds vs. sets vs. transplants then click on the Growing Franklin article that goes over the benefits of each type of onion planting.

It will be time to plant transplants in the garden as soon as we get a few more degrees of soil temperature increase.  If you have transplants under the grow lights, it is important that you harden them off for a period to acclimate them to their future outdoor home.  It takes about 3-7 days of gradually introducing transplants to outdoor weather and temperature before they will be adjusted and have success in the ground. Do not forget this step, it is important to do this to minimize transplant shock.




Update on Rain Events for Backyard Growers, Community Gardeners and Urban Farmers.

A recent article in The Ohio State University’s College of Food, Agricultural and Environmental Science news feed gives details that producers at all scale levels may find helpful when planning their site, tillage, drainage and planting plans.

CFAES News, March 13th, 2019, Author Credit: Alayna DeMartini


Click HERE to read the full article.