My green-eyed monster of jealousy peeked at me this week. While scrolling Facebook, I saw lots of seedlings from fellow gardeners. I want seedlings, but I can’t start seeds indoors. For some, sunlight or space are issues. For me, the problem is the moisture level. After mold exposure in 2008, I have a low tolerance for mold and mildew, and the increased moisture from indoor seedlings brings old symptoms back. I really don’t want to buy tomatoes, peppers, eggplant and other plants, and I don’t want to wait until after the last frost date before planting seeds. Fortunately, there are other alternatives. Some of these options allow for planting directly in the ground, while others are geared toward planting in pots to transplant later.
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Spring and summer annuals are often started indoors either because frost is still expected or the soil hasn’t warmed up enough for the seeds to sprout. If indoor sowing isn’t an option, try one of these alternatives.
Winter sowing is my favorite concept for starting seeds outdoors, and one day, I’m going to do it for most of my garden. The seeds that have endured winter seem to produce hardier plants than the ones I’ve sown in spring. Basically, you plant seeds in transparent containers (like 2 liter bottles), water them well, and set them outside. Then you can forget about them until spring. When the temperature is right, they sprout on their own. For a more in-depth description, Get Busy Gardening has a step-by-step guide to winter sowing.
A mini greenhouse is a transparent bottle that’s placed over a seed. Cut the bottom off the bottle, and gently shove it into the ground around the sown seed. It needs to be at least an inch in the ground so that it won’t blow away. Check the bottle daily in case you need to water the soil, and remove the bottle if the leaves start to touch the sides. Between the heat and moisture, the leaves can burn if touching the sides of the bottle. For summer annuals, I plant with mini greenhouses a few weeks before the last expected frost. Frosts and cold winds are still expected for my area, so I double insulated the seeds with a water bottle plus a coffee creamer bottle. If it gets below 30, I can cover it with a 5-gallon bucket.
A greenhouse is a great choice if there’s space outdoors. It can be a permanent structure with a heating unit, or it can be a simple set-up of pallets wrapped in clear plastic.
Cold frames are typically boxes with clear, hinged lids that are tilted for maximum exposure to sunlight. A common height is 12 inches in the front and 18 inches in the back. Like greenhouses, these can be permanent structures or rigged with something like bricks and a window. My cold frame will only be used for a few weeks, so I just laid the window pane on top rather than bothering with a hinged lid. If ants are a pest in your area, it’s worth noting that they’re attracted to the warmth and protection of cold frames. You may find an infestation after a storm or cold front.
Low Tunnel or High Tunnel
For tunnels, metal or PVC pipes are bent in an arc over the garden bed and are covered with fabric or clear plastic sheeting. A low tunnel is usually 2-4 feet high. A high tunnel is basically a taller version of a low tunnel, so you can walk through it. Mother of a Hubbard has an interesting comparison with 10 reasons low tunnels are better than cold frames.
If daytime weather is warm enough but nights are too cool, you can start seedlings in pots outdoors and bring them indoors at night. It helps to have a rolling cart that the seedlings can stay on for a few weeks. To encourage sprouting by retaining warmth and moisture, slide the pots into Ziploc bags or other transparent containers. But open them slightly to vent them if heat or moisture build up too much.
Warm the Soil
Heat-loving summer crops won’t sprout (or will have delayed sprouting) if the soil is too cold. Raised beds will be warmer than trenches, so plant those first seeds higher — either in beds or in small mounds of soil. Also, while mulch is great at regulating soil temperatures during extreme hot or cold weather, layers of mulch will prevent the soil from heating quickly in the spring. Pull back the mulch at least a couple of days before you plan to plant seeds. Lastly, you can warm the soil by covering it with clear plastic or black fabric a few days before planting. If you’re going to plant only a couple of seeds, you can place a black plastic pot upside down over the spot instead of a sheet of plastic. Covering the soil with plastic, fabric, or inverted pots all work best on sunny days.
All of these tips, with the exception of a fabric-covered low tunnel or covering the soil to warm it, will need to be vented as the weather warms up, typically on days that are sunny and over 40F. Otherwise, you risk cooking your seedlings after they sprout. Venting can mean propping a door open, pulling back a side of plastic, or taking off the lid of a mini-greenhouse bottle.
With each option (besides warming the soil), the seedlings will need to be hardened off before fully braving the elements. Don’t skip hardening off. Even if the plants are used to bright sun and warm/cool temperatures, they will still need time to adjust to the wind.
Bonus Alternative: Barter
If you haven’t already noticed from my How to Barter post, I’m a big fan of trading. A lot of gardeners start more seedlings than they need, so ask around to find a friend who will either grow extra for you or who already has extra. Offer to trade something they can use. Or if they haven’t started seedlings yet, offer to supply the seeds, soil, and/or pots.
Do you start seeds indoors? Or do you use alternative methods of growing?