Seedlings need a bit of tough love before planting
It is graduation season and while the scholars in your life will not be crossing any stages in packed auditoriums, your seedlings are ready for the next level: transplanting. With or without ceremony, life goes on — the kids grow up.
The kids we’re talking about here are seedlings. Ben and his wife Sam got bored mid-winter and started their seeds too early.
Even after moving most of their seedlings to larger pots, they are now rootbound and itching to sink those roots into the earth. (Much like my son himself who left for agriculture college more than 10 years ago.)
Here are our top six tips to ensure success when you start to move your seedlings — whether you grew them
yourself or recently purchased them — to the garden: 1) Start with the tough crops. Arugula, Swiss chard, kale, leeks, broccoli: these are some of the “cold crops” that are tough enough to stand up to a cold spell, should Jack Frost return for one last icy breath. If you have elected to start some from seed, get them out of the way first so your more heatsensitive crops have a couple more weeks to fill out as they continue on indoors. 2) Toughen them up by “hardening off.” This means leaving them outside in the sun for a few hours each day to get them used to being outdoors, gradually leaving them for an hour longer each day over about five to seven days. This helps minimize the shock of going from a cosy indoor environment out into the garden where temperatures fluctuate, wind blows and sunlight can be intense. While hardening off, keep your seedlings on the damp side. 3) A cold frame helps. This is a bottomless box that sits on the ground and has a clear cover with an angle of about 15 degrees tilted toward the sun (south or west).
Think of it like a mini-greenhouse. A cold frame — which is really a warm frame — is useful for hardening off since it retains heat during the day that can carry plants through a frosty night. As the days get warmer, prop the lid open for ventilation. A cold frame exposes plants to outdoor temperatures better than a heated greenhouse or a window in your home, and this helps make the transition to the garden easier on seedlings. 4) Nutrients. At planting time, add nutrients in the form of fertilizer or compost — or both. We spread a few centimetres of finished compost, manure or earthworm castings for soil health. The earthworms and microbes will rejoice at the availability of carbon organic matter, mobilizing the goodness throughout the root zone. Resist the urge to “turn it in” or disturb the soil since these tiny creatures have developed a soil structure to move moisture and nutrients. But the structure is easily destroyed by tillage.
If you are fertilizing, look for something that is slow-release and follow the directions on the label. The production of synthetic fertilizer is energyintensive, another reason we tend to favour compost, which helps store carbon from the atmosphere by improving the soil structure. There are a host of organic fertilizers on the market that do not require energy-intensive synthetic production. Many are derived from essentially the same material as good compost. 5) Loosen up. Root-bound plants need those roots released a little. If you see more roots than soil inside a seedling’s pot, loosen the mass to encourage it to more quickly extend new roots into the soil. 6) Water. Before you remove the seedling from its pot, water it thoroughly. And drench the planting hole. This minimizes transplant shock and stress until the roots start growing again. After planting, water your seedlings again and thoroughly, then allow the surface of the soil to dry; this trains the roots to grow deeper and helps plants fare better during dry stretches.
Congratulations. You and your seedlings have now graduated and you’ve done everything to set them up for success.