Time to Start Seeds?

Posted: March 5, 2012

Plants vary in the length of time they need prior to transplanting.


A question I often get asked in the Extension Office is: When should I start my seeds indoors for future planting in the garden?  This really depends on when the plants you are growing can normally be grown outdoors.  The range varies from four to ten weeks from when you sow the seeds till transplant time.  Plants vary in the length of time they need prior to transplanting.


Not all seeds do well in a transplanting situation; some plants do best if you direct sow the seeds into the garden.  These plants usually are delayed in production if they are planting from transplants.  Then there are those that do well as transplants, they usually flower sooner and produce an earlier harvest when started from seeds indoors.


There are several vegetable plants that do well as transplants.   In our zone 6 most cool season plants can be started now, late February.  These cool season plants are broccoli, cabbage, cauliflower and head lettuce.  Once you have hardened off the plants they will tolerate a light frost when planted in the garden.  The warm season plants that we can seed for transplant in late March are tomato, eggplant and peppers.  These plants, as they grow from seeds, need to be kept warm and will not tolerate any cool weather or light frost once placed in the garden.  The most delicate of vegetable transplants are the vine plants, cucumbers, cantaloupe, squash and watermelon.  You will need to wait until late April to start these seeds for transplanting.  They also do not like to have their roots disturbed when transplanted so it is best to sow their seeds directly into peat pots.  Then you simply plant the whole peat pot into your garden. Remember to always keep your peat pots warm while the vine plants are germinating and growing prior to transplanting them into your garden.


If you are reusing containers, like wood or plastic flats, or plastic pots you need to make sure they are properly sterilized before using them.  Wash them thoroughly in soapy water.  Do Not put wooden and plastic flats or plastic pots in an oven, this will not sterilize them.  Clean the wood and plastic items thoroughly and then rinse them in a solution of one part chlorine bleach and 10 parts water.  Once washed and rinsed allow them to dry before filling with your potting soil.


Seedlings need to receive bright light promptly after germination.  A good place to put them is in a bright south window.  If a large, bright window is now available for you to set the seedlings, you can use fluorescent lights.  A fixture containing two 40 watt fluorescent tubes will work as grow lights for you.  Place the seedlings about 6 inches from the tubes and keep the lights on for 14 to 16 hours each day.  As the seedlings grow, raise the lights to prevent the any leaf burn due to them touching the tubes.  Plants need both red and infrared radiations.  Since this is not available from common fluorescent tubes you will need to provide additional light from incandescent lamps or windows.  You can purchase special fluorescent tubes specifically designed for growing plants into your fixture.  These tubes cost a little more than the normal fluorescent lights and are sold under various trade names.


Most plants prefer night temperatures to range between 60 and 65 degree Fahrenheit.  Your day temperature should be about 10 degrees higher.  Leggy plant growth develops if you have temperatures warmer than this.    If you are growing cool season vegetables for transplanting, the temperature at night should not exceed 55 degrees Fahrenheit and 65 degrees Fahrenheit during the day. 


Your plants also do best if you provide extra humidity.  This can be accomplished by using a room humidifier or gravel filled shallow pans placed around your pots.  Do not allow your plants to wilt at any time and only keep the soil moist not soggy.


Once the seeds germinate you can apply a water soluble fertilizer at half strength a few days following their germination.  Then fertilize at two week intervals following the manufacturer’s recommended rate.

Be careful because young, tender seedlings can be easily damaged by too much fertilizer when they first germinate.


Prior to planting in your garden your transplants will need to go through a period called, hardening off.  This process should be started at least two weeks before planting in your garden.  Move your plants out of your house and into a cooler shady spot outside.  If you have a cold frame, this is a good place to move them.  Keep them in the shade for several days, and then gradually move the plants into the sun for short periods of time each day.  Increase their exposure each day to the sun.  Do not place your tender plants outdoors on windy days or when the temperatures are below 45 degrees Fahrenheit.  Also reduce your frequency of watering to allow the plants to become accustom to less moisture, but do not allow them to wilt.


A couple tips when transplanting into your garden.  Select a cloudy day to do the transplanting.  This helps reduce the shock of the transplant.  In warm sunny weather make sure you cover the newly planted seedlings with a newspaper tent or some type of shade protection for two to three days, until they get established in your garden. And most important, once in your garden, make sure you keep the new transplants properly watered.