Gardening Advice - Should I plant seeds or starts in the garden?


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When I installed a greenhouse five years ago, for the first time I had to ability to start a large number of plants early. I was so excited I started everything early in the greenhouse with the idea that it is always best to get a head start on the natural limits of cold weather and soil temperature. I've learned that this isn't true for every plant in the garden. Even if you don't have a greenhouse you will soon be faced with store shelves and farmers' market tables loaded with lush green plant starts that are hard to resist. The immediate satisfaction of a real plant is certainly more fun to buy than a pack of seeds but like most things in life, delayed gratification is one of the key lessons of gardening.


There are a couple things that are helpful to know when buying plant starts. Biggers is not always better. There is not a big advantage to buying a two-foot-tall tomato plant that is already flowering vs. the less expensive eight-inch start. In my experience the smaller plant usually catches up to the big one when they are planted in the garden and they end up bearing the same amount of fruit with similar timing. The problem with the large plants that sometimes already have tomatoes on them is that once they are out of the climate-controlled environment of the greenhouse and in the cool soil of early summer they slow down and their growth stalls out. When the temperatures heat up they get going again but by that time the other smaller plant has caught up with the bigger plant and it's a wash.


Another good example of this is pumpkin plants. I have always worked with the assumption that the best way to grow giant pumpkins is to start the seeds really early. It made intuitive sense to me that the earlier I started the seeds the bigger the pumpkins will get, but it turns out this isn't true. I spoke with the winner of the giant pumpkin contest at last summer's Spokane County Fair and asked him about his timing for starting seeds. He explained that he starts the seeds at the beginning of April and plants them in the garden at the beginning of May under plastic. I don't know the science behind it but in retrospect I understand why this works. I've learned that once squash plants start growing they like to keep growing and don't respond well to having their growth disrupted by transplanting or the shock of moving from the friendly confines of the greenhouse as a large plant to outside in the garden. When I have started squash plants really early and planted them as large plants they tend to sit in the garden for a long time without growing. When the plants are smaller they tend to make that transition more smoothly. 


One other consideration when buying plant starts is the issue of sustainability. Bigger plants means that more energy has gone into defying the local climate. In the past I've noticed that Home Depot is packed with plants from Texas. Smaller plants grown locally are generally more sustainable. Farmers' Markets are the best place to buy starts. The big plants are also expensive to buy.
While you don't necessarily need giant plants to grow a successful harvest of vegetables there are certain plants that are best planted in the garden as small plants instead of seeds.

I recommend buying and growing plant starts for:


Winter Squash (pumpkins, butternut, spaghetti,etc.)
Summer Squash (zucchini, scallop, crookneck)
Cabbage/Kohl Rabi/Kale
Marigolds (these are great companion plants for a vegetable garden and I always start some early but also direct seed them)


Summer squash, like zucchini, and cucumbers can be successfully planted as seeds but I have problems with birds that love to nip at the young plants. They leave the bigger ones alone so, if I have time, I plant these as starts. If I don't get around to starting them early I plant the seeds in the garden but plant twice as many seeds as I need, anticipating that the birds will kill many of them. The one advantage of starting squash plants from seed in the garden is that they don't like to have their roots disturbed so this method avoids the shock of transplanting them. Take note that it's beneficial to loosen the roots of most transplants before putting them in the garden, but squash plants are the big exception to the rule. I always plant winter squash as plants because they usually take around 100 days to mature and I like to get a little head start.


Plants that are best planted as seeds in the garden:


Corn (don't bother growing in a backyard garden)
Bunching Onions
Carrots, Beets, Parsnips, and other roots crops
Lettuce & other greens
Cucumbers (if birds aren't an issue)
Sunflowers (I start these a couple weeks early but it's not really necessary)
Potatoes (buy seed potatoes and plant directly in the garden)


I know I'm forgetting some so let me know if you've got a question about a plant not mentioned.