Seedling Diagnosis

Depending on when the last frost date is in your area, by early March you’ve either begun your seeds indoors, or are gearing up to start.  There is a lot of hope in those packets of seeds, but sometimes hopes can be dashed if everything doesn’t go as planned.

Even under the best circumstances, you might run into a few problems. Here’s a list of a common symptoms and the corrective measures you can take to solve them.

Symptom: Spindly or Leggy Growth
Causes: Low light, too much water, excessively warm temperatures, over fertilization, crowded plants.

Corrective Measures:
Some seeds will germinate without much light, but seedlings need bright light.  Use grow lights if a sunny window is not available.  Position the lights 4 inches above the seed tray and leave the lights on for 16 hours a day.  Don’t forget to raise the lights as the seedlings grow taller.

Provide an air temperature of 70 to 75 degrees during the day and night temperature of at least 60 to 65 degrees.

Soil should be kept consistently moist, but not soggy. Mist with a spray bottle or water from the bottom up by placing the containers in a pan filled with 1 inch of warm water.  Once the soil is moist, remove the seed pots from the pan.

Wait until seedlings have produced their first set of true leaves to fertilize.  This is actually the second set of leaves that emerge.  Use a liquid fertilizer diluted to half strength.  Feed once a week.

Sow seeds and thin seedlings according to the packet instructions to prevent overcrowding.

Symptom: Dwarf Plants
Causes: Low fertility.

Corrective Measures: Because there is so little soil, nutrient levels are hard to maintain.  As mentioned above, feed with a liquid fertilizer diluted to half strength after the first set of true leaves emerge. Feed once a week.

Some seed starting soil mixtures contain nutrients such as Mycorrhizae, a naturally occurring fungus that promotes strong root development.

Symptom: Decay or rotting of the stems of young plants near the soil surface.
Causes: Damping-off. Disease organisms attack germinating seeds and young plants, especially during prolonged cloudy weather.

Corrective Measures:
Use a sterile soil-mix designed for seed starting.

Mound the soil in the container so that it is flush with the edge of the pot.  This will allow air flow across the surface of the soil.

Symptom: Wilting followed by death of the seedling.  Tiny insects hovering around soil.
Causes: Fungus gnat larvae will feed on the roots of the seedlings.  Adult fungus gnats are those pesky, small flying insects that hover around potting soil.  They are attracted to moist potting soils that have a high organic content.

Corrective Measures:
Use a well draining potting soil.

If you see the adult gnats, cut back on water to make the soil less attractive to the adult female gnat. You don’t need to stop watering completely, just allow the soil to dry out between watering.

Placing a moist slice of potato on top of the soil will attract the larvae.  Throw out the potato slice to get rid of the larvae .