Starting garden plants indoors gives you a bigger selection over what you can buy at local garden centers for growing on in the backyard, and it can give you more plants at a savings, not to mention change your whole perspective during the cold season. But, while it’s true that getting the outdoor garden going with established plants extends and increases your harvest, it’s best not to get growing too early. At least not unless you’re totally prepared to accommodate all the needs of your young plants as they increase in size.
So, when should you sow your seed to get plants large enough to produce well before cold weather returns? If you’re looking for a date, there is a different answer for every climate zone. People in Texas are already gearing up to get their seeds started soon, while those living in Wisconsin or Manitoba shouldn’t start germinating outdoor plants for at least 6 weeks. Even then, the plant type itself has a lot to do with when you should get propagating. Slow to grow garden favorites like peppers, both sweet and hot, you do want to start several weeks before other large plants like tomatoes. Early season crops like lettuces and greens you can actually bring to harvest under a quality T5 high output fluorescent fixture… so why wait? Grow some now and harvest in time to start some for growing outdoors too.
Read the seed packet! It will tell you when to start indoors in terms of how long it takes to mature. Armed with some climate zone growing season length to subtract from this length of time gives you a good idea of how many weeks worth of jump you need to start each crop indoors. Generally, 8 weeks before the last threat of frost is a reasonable rule of thumb for rolling out the propagation gear and sowing your seed. Give peppers at least a 3-week head start on everything else – they are ridiculously slow at sprouting and enlarging.
Ever wonder why greenhouses grow all vegetable starter plants in flats? It’s not just because gardeners prefer getting 4 small plants for a dollar or two instead of spending $5 each. They have space limitations too, and potting up those thousands of itty bitty plants living in 4-pack cell condos in those trays means they would have to increase their indoor growing area immensely, as well as install a boatload of supplemental lighting. Now consider how much room you’ve got to grow your outdoor garden seedlings in your home. It’s the rare person who has enough room to get started so early their tomatoes and peppers are each nicely filling out 4″ or 6″ pots by the time its safe to plant outdoors.
Wait – you need lighting in a greenhouse??? Yes, and it’s necessary to raise the incredibly vigorous plants. In fact, greenhouse plants in places with lots of winter clouds are stunted. Even with lots of sunny days, remember the winter sun is weak, which means that a good chunk of energy it gives to plants is missing. If you suspected that next I’ll say that this is why there is NOT enough sun power in a ‘sunny’ window to grow strong starter plants – you’re right. You don’t just need “some grow light” you need “adequate grow light.”
So, what is ‘adequate’? One propagation tray needs a minimum of a 2′-4 tube T5 HO grow light fixture, and if you don’t have the growing space surrounded by reflective surfaces, the plants on the outer edges will be leaning toward the center trying to get more light. You need to run that light 16 hours a day too. Of course, if you prefer to get a jump start on the season and ignore what experience has taught your forefathers in growing indoors, you can. Just know going into it that once planted outdoors your little tomatoes, peppers, eggplants, and whatnot are going to spend several weeks repairing the issues your carelessness has created BEFORE they can get back to making you a crop.
When you take those protected seedlings raised under the least amount of light possible outdoors, the wind will be like a hurricane even on a calm day because they haven’t developed the muscle needed to move with the breeze instead of being bowled over by it. A small oscillating fan that stirs your wee plants during day hours in your indoor seed starting space helps them grow stronger in preparation for the real world. While you can stake them all and help the coddled garden starters overcome this milk toast trait from growing where there was no moving air, it’s a pain to do, requires a lot of time and extra materials, and a task that is avoidable on more plants if you’d only acquired a fan. Additionally, this air movement deters pests and disease too.
Now, go out and procure your seed. If you wait another month the really cool stuff will be in slim supply, especially the hot peppers and most awesome tomatoes.