Hardening Off and Transplanting Seedlings

 

Photo by Brooke Coburn

It is time to begin to transplant tender seedlings outdoors, and seedlings that have grown indoors up to this point need special treatment before being planted outdoors. These seedlings are used to lower light levels, protection from the elements, and ample water. So they will need to adjust gradually to the outdoor environment, a process called hardening off.

Heatwave in the Garden: how to identify and prevent heat stress in plants

 (Reposted from Oregon State University Extension June 2021)

When a heatwave hits, plants may show the impact.

• Most plants grow best in temperature ranges 59-86F.
• When temperatures above 90F are sustained for long periods, plant growth is slowed, and some plants begin to show signs of stress.
• Above 104F, many plants will survive but will show different signs of heat stress dependent on plant type, maturity of the plant, and factors that often come with high temperatures, such as drought or wind.
• Extreme air and soil temperatures slow down chemical activity and growth in plants.

What are signs of heat stress in plants?

To direct sow, or not... what to do? by Vicky Spelman

John Porter - The Garden Professors

Transplant definition:  is the technique of moving a plant from one location to another. A fully germinated seedling is moved and replanted in a permanent location for the growing season.

So, why do we take the time to start seeds indoors?  Or the added expense of buying transplants?

1. Many plants that we start as transplants require minimum soil temperature of around 60ºF – with optimum germination between 70º-80ºF.  Waiting for the soil to reach these temperatures can shorten the growing season.  

2. You can extend the growing season by starting warm season crops by having a plant ready to go once weather conditions are favorable.  

Direct sow definition:  means that you start planting seeds in the garden, rather than buying small plants or starting seeds indoors earlier and transplanting them outside.

Why plant seeds directly into the garden?

1. Ease – Easier and less intimidating to just plant seeds into the soil versus starting seeds indoors.

2. Cost effective – Pack of seeds cheaper than buying transplants and/or equipment to start indoors.

3. And... Some plants don’t transplant well.  Root crops – like radishes, carrots and beets – don’t transplant well, and others likes cilantro and zinnias don’t do well with root disturbance. You would want to start cilantro and zinnias in large enough containers so you don’t have to repot them, and plant carefully to not disturb roots.

The seed packet will help with determining your grow method.  Some warm season crops – like beans, corn, cucumbers and squash can be started indoors and transplanted, but not necessarily needed – these crops typically grow much quicker from seeds and are hardier.  Other warm season crops – like tomatoes, peppers and eggplants should be started as transplants to take advantage of being planted in warmer temperatures.

Cool season plants – like lettuces, spinach and root crops - can be direct sown into the garden before the last frost date.  

Here is a graphic from Virginia Cooperative Extension for some guidelines – keep in mind your local area and growing conditions and remember to check your seed packet.  

Courtesy Virginia Cooperative Extension
John Porter's Article

A soil thermometer can help when determining soil temperatures get in range for direct sowing outdoors.  

Complete Article:  To direct sow, or not to sow – published by John Porter