Module 4 Seed Starting Basics

Module Overview

Seed starting involves techniques for germinating seeds and maturing them into seedlings. Seed starting under LED lights can be done in the classroom any time of the year. It provides opportunities for students to closely observe plant growth on a daily basis. This module outlines the materials and process for sowing seeds and growing seedlings under an LED light in the classroom.

Learning Goals

After this module, learners will be able to:

Define “seed starting”
Identify basic seed starting principles and equipment needed for seed starting
Reference a suggested seed starting timeline
Set up seed starting materials and sow seeds indoors
Use appropriate watering techniques for seed starting
Grow seedlings to the point at which they are ready for transplanting

Roadmap

These items will all appear, in order, in the module.

READ: Seed Starting kit materials list
READ & WATCH: Seed Starting Principles
READ: GTS Seed Guide
READ: GTS Planning and Planting Chart
ADDITIONAL RESOURCE: Seed Starting Webinar, Franklin County Extension

Please click NEXT at the bottom of this page to advance through the module. To return to the list of modules, PC users click “Modules” in the top left corner, App users click the back arrow in the top left header.

Seed Starting Materials List

An aerogarden box and a box with indoor growing kit supplies These are the suggested materials needed for indoor seed starting.

10″ x 20″ flat tray
32 cell inserts
Humidity dome
LED grow light panel
Water-soluble tomato plant food
Timer
Spray bottle
Seed starting potting mix

Seed Starting Principles

Seed starting is process of germinating seeds into transplants. In GTS, the transplants can be matured under LED lights or planted outdoors in your raised beds for later harvest.

The Planting Medium

Indoor growing supplies on a table include LED lights, potting mix,
aerogarden, extension cord, timer, seeds, pots. — Purchase high quality materials, clean materials thoroughly, and store them carefully. Label materials so they won’t be discarded.

When planting seeds in pots under LED lighting, we recommend using seed starting mix. This mix is not made of just soil, but includes mediums like peat moss, perlite, or coconut coir. It holds water very well, but also drains very well and promotes easy germination and rapid seedling growth.

Pre-moisten the seed-starting mix in a bucket before adding it to your pots. The mix should clump together like a loose snowball. Next, add the mix to top edge of pot and gently firm it down to create the seed bed.

Adding Seeds

Seeds generally need to be covered and receive adequate moisture and light in to germinate. Plant 2-3 seeds in each 2”x2” pot. Add soil on top 3 times the seed’s diameter.

Humidity and Watering

Once planted, the seeds and seedlings must remain slightly moist. Seedlings in a tray are covered with a humidity dome to trap moisture.

When seeds are first planted, use a mister or sprayer to hydrate the seed bed and fragile seedlings, or water gently under a faucet.
Next, fill the bottom tray with about an inch of water and set your pots in the tray for about 30 minutes to allow the growing mix to hydrate from the bottom. After germination you should only use the bottom watering technique.
After 30, or once the soil is fully hydrated, remove the pots from the bottom tray, empty the remaining water, and place the insert tray with the pots back in the bottom tray.
Cover the pots with a humidity dome until numerous seeds germinate. If you do not have a humidity dome, cover lightly with a sheet of plastic or plastic wrap. Be sure to open the ventilation holes in the dome or to create small ventilation holes in the sheet of plastic.
Remove dome or plastic cover after seeds germinate.

Lighting

Plug the LED light into a timer unit that you plug into an electrical outlet. Be sure to check that the light is coming on and going off at the times you intend. A timer is critical to ensure that the plants get the required amount of light. If you do not have a timer, buy a timer! Seedlings will generally germinate and grow best with 12-15 hours of light in a 24 hour period.

Thinning

Seedlings will thrive best if there is only one plant per pot. See Module 8 for further guidance on thinning.

Fertilizing

Seeds and seedlings need a complete fertilizer to thrive. Seed Starting Mix contains only a small amount of fertilizer. A good seed starting mix will generally only provide all the nutrition for seedlings to grow for a week or so. Continue to fertilize using the bottom watering technique (above), mixing water-soluble fertilizer into the water. Be sure to closely follow instructions on the package for the proper proportions. See Module 13 for further guidance on fertilizing.

Seed Starting in 4 Minutes

Check out this seed starting video for a visual description of the processes described above.

(4 minutes, 6 seconds)
Watch this video on YouTube to access a full text transcript.

Tips and Tricks

Plants uptake their water, oxygen, and nutrients through the soil. The greater the soil volume they have in their pot, the greater their capacity to store and utilize water, oxygen, and nutrients.
Make sure your humidity dome or saran wrap is removed once germination has begun, otherwise plants can become too moist and predisposed to disease.
Set your LED timer to 12-15 hours a day. This will simulate the amount of daylight that would be outside in the summer.
To minimize the amount of “green” around the top of the plant , you can sprinkle a small layer of vermiculite on top when you sow your seeds.

Seedlings very crowded in pots. — These seedlings were not properly thinned. They are tall and leggy, which may be a sign of nutrient deficiency.

Baby tomatoes are growing in an AeroGarden. They are wilting. — These wilting baby tomatoes are too close to the light and may not have enough water.

Baby collard greens planted one per pot. Yellowing present on the leaves. — The yellowing on these baby collard greens signifies a nutrient deficiency and need for fertilizer.

Bottom Watering

Watch the following video to learn about the bottom watering process and best practice.

(1 minute, 24 seconds)
Video Transcript: Bottom Watering

Tips and Tricks for bottom watering:

We recommend pots are removed from the insert and placed in water in the bottom tray so they fully hydrate before they are replaced in the insert to drain.
If water is added to the bottom tray while the pots are in the insert, and the plants are just getting started (meaning the roots have not extended out the bottom of the pots), the pots will stop taking up water once the level drops below the level of the insert.
Do not leave standing water in the bottom tray when plants are not being bottom watered. Standing water can cause the tray to grow algae, which means it will have to be cleaned before water is added again.
As your plants grow a great root system, the roots may grow down into the bottom tray through the holes in the insert and then continue to take in water. This may also make it more difficult to remove them for transplanting, so be gentle when pulling the pots out of the insert.
If you need to leave for a week-long break, we recommend you remove the pots from the insert and place the pots directly into the bottom tray. You can then put 1-2 inches of water in the bottom tray and leave the pots to use the water up over the week-long break until you return. We recommend you do not leave the pots in water continuously on a regular basis, as the roots could drown. Leaving the pots in a tray of water is only a short-term solution for keeping them hydrated over a breaks and ensuring they will stay alive until you return. Plants do not drown in the AeroGarden as the AeroGarden adds oxygen to the water when the pump cycle runs, which provides a constant source of fresh oxygen to the plant roots.

GTS Seed Guide

Use this Seed guide when planting each month.

Downloadable PDF: GTS Seed Guide

Planting Instructions by Seed Variety
	When to Plant	Where to Plant	Days to Germination	Days to Harvest	Special Instructions
Round Radishes “Easter Egg II” Raphanus sativus	September	Direct seed in raised bed	3-7	28-32	Space or thin to at least 3″ apart. Use paper towel planting method with lower grades.
Cilantro/Coriander “Cruiser” Coriandrum sativum	September	Direct seed in 12-18″ raised bed	7-10	50-55	Can plant in pots, also, to grow indoors under LED lighting or outdoors. Recommended spacing is 3-5″.
Basil (in pod) “Genovese” Ocimum basilicum	September	Plant two pods in the AeroGarden	6-12	30-60	Harvest top growth to keep plants bushy and productive.
Sugar Snap Peas “Sugar Ann” Pisum sativum	September	Direct seed	7-10	42-56	Plant as soon as possible. Seed along the north or east side of the raised bed, if possible. Recommended spacing is 3-4″.
Bok Choy “Bopak F1 OG” Brassica rapa var. chinensis	October	Seed start under LED lights	7-10	50	Can transplant to raised bed or larger pots for a December harvest. Recommended spacing is 6-12″.
Kale Any curly type Brassica oleracea	November	Direct seed in raised bed	7-10	60	This is a hardy, curly kale. Leaves can be harvested at any size. Recommended spacing is 4-6″.
Spinach (savoyed) “Bloomsdale” Spinacia oleracea	November	Direct seed in raised bed	10-14	21-35	May have poor germination. Will grow slowly in cold months. Recommended spacing is 4-6″.
Lettuce (Bibb) “Buttercrunch MT0 OG” Lactuca sativa	January	Seed start under LED lights	3-5	28 to baby, 46 to full	Thin to one plant per pot. Can transplant seedlings to raised bed. Recommended spacing is 6-12″.
Tomato (in pod) Red Heirloom Solanum lycopersicum	January	Plant one pod in the AeroGarden	7-14	28-42	Follow AeroGarden instructions carefully, including covering all the unused openings.
Collard Greens Vates, Top Bunch Brassica oleracea	February	Plant half the 2″ pots in the tray	3-7	50-55	Transplant to raised bed in March or April. Space at least 12″ apart. Can eat the leaves.

Planning and Planting Guide

Refer to this guide for oprimized schoolyear growing.

Planning and Plating Guide chart

GTS Planning and Planting Guide Image Transcript