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Starting Seeds Indoors

Updated: Apr 20, 2023

Germinating and starting seeds indoors is a way to get ripe fruit from crops that need a longer growing season (more than 100 days till harvest). This includes vegetables like peppers, eggplant, and tomatoes.

There are also many plants that have a better chance at survival when their seed is started indoors because there are no external weather factors to disturb them. Starting your own seeds is such a good way to get your hands in the soil while you are waiting for Spring to arrive.

The process of seed germination is fascinating. Seeds need three things for germination to be successful; adequate soil and air temperatures, even moisture and oxygen. Some seeds have specific requirements to their outer coatings in order to germinate, but in general the three above mentioned are the most common.

In a cliff notes version, the water rehydrates the seeds cell, which causes a root to emerge. It then develops root hairs allowing the root to absorb water, oxygen and nutrients from the soil. The seed feeds off of the stored food in the cell and then the cells divide causing the embryonic stem to unfurl. This is when we see the little stem with its cotyledons appear at the soil surface. The amount of time it takes for a seed to germinate depends on the species.


Here is a simple list of common plants that should be started indoors. This list assumes that the last frost date is June 1st.

It's always good to read the packages and see what the instructions are specific to the seeds you are growing.


Early March: Onion seeds (not sets)

Mid-end of March: Peppers

End of March: Tomatoes, Celery, Eggplant

Early April: Artichoke

Early to Mid- May: Cucumbers, Pumpkins, Squashes, Watermelon


End of March - Early April: Petunias, Snapdragon, Verbena

Early April: Impatiens

Early to Mid-April: Ageratum, Castor Bean, Celosia, ornamental Kale, Thunbergia (black-eyed Susan)

Mid-April: Coleus

Perennial Flowers

Early February to mid-March: Delphinium

Late February to mid-March: Sweet William

Early March: Lupine

Early to mid-March: Foxglove

End of March - Early April: Hollyhock, Rudbeckia

Factor in the time it takes to acclimatize your seedlings before you plant them in the garden (1 week).


Choose a container that provides good drainage. The container can be very small so that it doesn't use a lot of soil, choose the size of container based on the seed size. Seeds can be put into a small cell seedling tray or into Jiffy peat pots. Always watch how fast the soil dries out so that you can keep it consistently moist.


Seed starting potting mix is specially formulated to allow seeds to germinate quickly. The soil mixture must hold moisture while providing aeration. Garden soil is not recommended for starting seeds indoors. Instead, choose a soil-less mixture such as 1 part peat moss and 1 part vermiculite or perlite or 1/3 peat moss, 1/3 perlite, and 1/3 vermiculite. We recommend that you use a germination soil that can be found here.

Some seeds require special treatments to their seed coat. Always make sure that you read the information on the back of the packets, for example Snapdragons need to be frozen for 48 hours before seeding.


Now it is time to sow your seeds! Make an indentation in the soil. This keeps each seed in the center of the cell and prevents them from being bumped out of place or mixed up with other seeds.

Drop the seed into the center of the soil divot. Refrain from pushing on the seed with a tool. This can damage the seed coat. Some seeds need total darkness in order to germinate and some seeds need to be exposed to light. Read the back of your seed packet to find the germination requirements. If seeds need cover, you can layer vermiculite (finely crushed lava) over the entire top of the seeds and soil.


Watering is a crucial step for the success of your seeds. After seeding until germination, the soil must stay moist so the cotyledon can break through its seed coat. Spray your seedling tray with luke-warm water using a spray bottle. Extremely cold or excessively hot water will shock them. Try to avoid using chlorinated water or water that is high in salts and bicarbonates, if this is the only water source that is available, let it sit for 24 or 48 hours before using. In early spring, warm melted snow water is the preferred type of water to use. You can cover your seed tray or containers with a clear plastic cover to create a mini greenhouse environment until your seeds germinate. Gradually remove the cover once the seeds germinate. It is important to remember that any changes that you make to your seeds should be made at a gradual basis so that your seedlings don't get shocked.


Once your seedlings emerge from the soil, they need to be placed in full light. If you don't have grow lights then fluorescent lights are recommended as they are the closest color to sunlight.

Start by placing your light about 3 to4 inches above the seedling tray and gradually move the light up as your seedlings grow. If your seedlings do not receive enough light they will be very leggy, pale and will have huge gaps in-between their leaves. At the beginning your seedlings need about 14 to 16 hours of daylight or fluorescent light. More light than this can cause harm to your seedlings. You may want to use a timer for your light to ensure the success of your seedlings.

Pictured is the grow light that we sell at our greenhouse, to shop click here.


To germinate, the soil needs to be fairly warm (between 21.1 and 32.2 degrees celsius). There is a variation between different species so read the package or research what the ideal temperature is for your species. You can measure your soil temperature with a meat or soil temperature thermometer. If you are using a fluorescent bulb, place the seeds that need higher heat in the middle and then ones that need lower temperatures on the outside edge. If the room you are growing your plants in is quite cold, an additional heat source will be very necessary. A good additional heat source is bottom heat, we recommend using a heat pad like this one. Once the seeds have sprouted, remove the heat mat as you do not want to promote accelerated growth.

Monitor your seeds closely to make sure that they don't dry out.

Note: your seeds do not need to be fertilized, we recommend that you start fertilizing once your seeds have reached four to six true leaf stage. We cover this topic in our blog called "Taking Care of your Seedlings".

We wish you all the best as you start your seed journey, if you have any questions, don't hesitate to contact us. Next, we will talk about how to take care of your seedlings once your seeds have germinated!

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