I know garden season has started when doing stairs seriously becomes part of my workout routine and Jeff is teasing me for treating plants like babies! The dream is to one day have a proper greenhouse with an automated watering system and precise temperature control, but that day is not today and I have hundreds of seedlings I need to grow for our current gardens. I take a lot of pride in growing strong seedlings for the plants I transplant into the garden. This is an area I have researched quite a lot and tried a few different methods.
We currently grow all our seedlings in our basement (hence the stair routine). Jeff framed me a small room which we sealed off with black and white plastic and tuck tape. I have a table outside of the grow room which all my supplies go on and its at a good ergonomic height. However, I usually have 2 little people helping me and so the floor does become the more common seeding area!
I take a lot of pride in growing strong seedlings and the following are our top tips based on our seedling program. There are lots of great resources out there that cover seed starting more comprehensively but this will get you started!
Maximize Your Space
Our grow room is very small but we still manage to grow a few hundred seedlings in it thanks to vertical space. Inside our grow room we use metal garage storage racks with adjustable shelving. I have 4 shelves that I can plant on.
Temperature control is extremely important for consistent germination rates. Some seeds like tomatoes, peppers, squash and melons are heat lovers and need a lot of heat to germinate. Other seeds like cauliflower, broccoli and cabbage like things a bit on the cooler side. In our seed room we typically are just starting the heat lovers and our basement is quite cool so we do need a heat source. We use seedling mats for our heat source and we have found that placing a thin layer of foil bubble insulation under the mats makes them much more efficient. I definitely recommend using a thermostat temperature controller with your heat mats so that you can monitor your soil temperature and make your mats as efficient as possible.
Air Circulation & Humidity
This could make you or break you in the seed room! Young seedlings are hugely susceptible to damping off from fungal or microbial diseases. Obviously, keeping your seed room as clean as possible is the first step in preventing these diseases but making sure you have adequate air circulation and the right humidity is also very important. We use indoor fans and a programmable dehumidifier in our seed room and this works really well. We have a fan mounted up high in the seed room as well as one on the floor to keep air moving throughout the whole room. Plants require quite high humidity to thrive and as long as you have good air circulation you can maintain fairly high humidity without a problem, however you don’t want humidity at 100% either! Generally, we set our dehumidifier to a humidity level of about 75%.
Lighting is incredibly important for growing strong seedlings. From the moment seeds germinate, they start reaching for the light. If they have to really stretch, they get leggy and leggy plants break easily and don’t transplant well. To prevent this, you want light placed just an inch or two above the plants. We use Sunblaster Growlights and are very happy with them. We use link chains and S hooks to attach the ballasts to the shelves. As the plants grow we move the lights up the chains.
We bottom water just about everything. Bottom water greatly decreases the risk of fungal diseases and damping off in your seed room because the foliage of the seedlings never get wet. It also promotes strong root growth as the roots stretch down towards the water source. To do this we use seedling trays that do not have holes in the bottom. When we water we pour enough water in the tray, that after a few minutes, we should see the top soil evenly wet across all of the seedling cells. We do not water every day, after seeds have germinated we allow the soil to begin to dry out before we water again. Generally speaking this means we are watering every 2-3 days.
Hardening off is crucial for the survival of your transplants. It’s my least favourite part of the seedling process. The worry often with hardening off is around cold, but heat and low humidity are often more of a concern when hardening them off. We move the plants outside for very short amounts of time and try to keep them in a shaded area. We then increase the time and amount of sun the plants are exposed to until they are spending the day outside. Hardening off is time consuming and can be a pain but it is crucial for transplanting success and reducing transplant shock.