Starting Flower Seeds Indoors

Starting flower seeds indoors is a great option when starting a flower farm on a shoe-string budget (like I did). It’s certainly more affordable than a greenhouse, HOWEVER, it does still require a significant investment (more on that later) and additional attention to detail.

It works just fine to start handfuls of trays indoors, but it does become inevitable at a certain scale to upgrade to a greenhouse. Starting seeds indoors can be done carefully, but it’s not ideal. Often, seedlings can’t get enough light so they end up stretching, producing “leggy” and unhealthy plants. It also can be difficult to achieve enough airflow to prevent stagnant air and fungal diseases from forming. Water management is also a great challenge indoors, not to mention that lugging trays of soil and water around your house makes an incredible mess. Plus the humidity can destroy your home!

Greenhouses provide more light, more air movement, less mess, better water management options, and more space. It also keeps the dirt and mess out of your living room. -Trust me, after a while you’re going to want to separate your work/home spaces at least a little bit. I prefer to start seeds in a greenhouse, however, I will sometimes start seeds indoors under one condition: I only start seeds indoors under lights if I only have a few trays to start VERY early in the season, when it doesn’t make sense to pay to heat the entire greenhouse. Most of the time it’s more cost effective to buy in plugs at that point. I still know some larger growers who start all of their seeds indoors, and who have good success with it, but my advice is to prepare to invest in a propagation house (seed-starting greenhouse) in the future.

Let’s dig into how to best set up and manage your indoor seed starting room to avoid pests, disease, and for the best success.

RACKS & SHELVING

Purchase racks that do not have a solid bottom- you want as much air as possible to hit the bottom of your cell trays. The restaurant wire shelving storage racks work great and are easy to obtain at hardware or restaurant supply stores. You can even get castor wheels to easily install on the legs so you can wheel the racks around! Avoid using wood, as it will eventually rot or encourage fungal growth due to the excess water and humidity. Most of the time these racks range in price from $95-$150 in price, depending on the size.

LIGHT

Fluorescent lights are a MAJOR expense for starting seeds. We spent well over $1,500.00 on our indoor seed starting lights when we made our first set up. You could probably do it for cheaper, but you want to get high quality fluorescent ones that can stand up to excess moisture and dirt. You may want to consider if this cost may be better spent invested in a propagation house (greenhouse).

In order to provide plants with the full spectrum of light (we’re mimicking light from the sun), you need to purchase both cool white and warm white fluorescent bulbs. Warm white bulbs produce infrared radiation. This is a big mistake I see new growers often make, so be sure to get BOTH types of bulbs, otherwise your seedlings will suffer. You can get them anywhere, most hardware stores carry both.

The light fixtures should be positioned above the flats, and should be adjustable in height. A simple chain can be used to adjust them by lowering or raising the links on the chains. Position the lights about 4-6” above the tips of the plants as they grow.

Lights should stay on for about 14-16 hours a day, and you can automate them easily! Simply get a light timer online, and set it to turn on and off at the same time every day. I highly recommend this - I didn’t do it at first and constantly forgot to shut the lights off at night. The plants grew excessively, did poorly, and our electricity bill went up!

HEAT

The room should be around 64-73*F, which can easily be obtained indoors using a space heater. You can automate the heater by purchasing a simple digital thermostat temperature controller (Inkbird is a popular brand, it can be purchased on Amazon). Set the desired temperature, and it will automatically turn the heater on and off to maintain that temperature. I highly suggest using one of these for your heat mats as well!

HUMIDITY

This may be the most challenging part of starting seeds indoors. Humidity should be around 60-90%, and in the winter/early spring that can be very difficult to achieve. We heat our house with wood, which is extra drying, so our house is usually between 20-30% humidity in winter. You can easily raise humidity in a smaller room with a humidifier, however, there can be consequences…

High humidity and your home’s drywall don’t mix very well! Keep in mind that high humidity can destroy the room you are starting seeds in. It might work best to start seeds in a bathroom, which usually has moisture-resistant drywall and an exhaust fan to combat the high-humidity environment. Control humidity with a timer-controlled vaporizer or humidifier. You can purchase ones that mist for 10 seconds or so every 20 minutes, or maintain a steady humidity level. Utilize humidity domes as much as possible to get the best germination rates.

VENTILATION & AIRFLOW

This is another tough aspect to get right indoors. There should be TONS of airflow, so be sure to set up multiple fans that move the air horizontally. The fans should not be blowing directly on the seedings, as it will dry them out quickly, but rather should be moving the air above them and around them. This is so incredibly important to minimize stagnant air which will lead to fungal diseases!

WATER

Watering can be a nightmare indoors, since you really can’t overhead water in your home without flooding the place (good luck explaining that to your family!). Misting can be just as messy, which makes giving germinating seeds the right humidity and moisture a challenge. Because of this, most of the time you’re forced to “bottom-water” by placing your trays in larger containers and adding water for the soil to wick up. It’s not ideal for germination. But bottom-watering is much less messy than over-head watering, and is just about the only way to not get everything wet in your home. This makes the soil prone to over-saturation, poorer drainage, and fungal diseases such as damping-off. You’re just asking for fungus gnats! You don’t want those in your home, so you’ll have to pay extra attention to detail when it comes to water management.

GREENHOUSES

Next week the third part of this series will release, with a guide all about propagation houses (aka growing seedlings in a greenhouse). The guide will talk about essentials for greenhouse set up, greenhouse structure options, investment, fuel sources, and equipment.

Questions about any of this stuff? Drop ‘em below!