News / Life / Clark County Life

Gardening with Allen: Growing from seed outside is easy

By Allen Wilson

Published: February 5, 2022, 6:00am

Sprouting seeds, then carefully moving them to individual cells is an easy and compact way to have transplants ready to fill in spaces opened up by harvested vegetables.

I planted a small vegetable garden last year and want to plant more this year. Which vegetables can I plant from seeds and which should I use started plants?

Gardeners have become so used to planting started vegetable plants that they do not realize how easy it is to start many from seeds planted directly outside. Some of the more cold-tolerant vegetables can be planted outside quite early.

First, we need to define which vegetables are cold tolerant or “hardy” and which are “tender” or easily damaged by light frost. If you eat the roots, stems, flower buds or leaves, it is a hardy vegetable.

The two exceptions to this rule are potatoes and sweet potatoes, which are tender. If you eat the fruit of a vegetable, it is tender. The two exceptions to this rule are peas and fava beans, which are hardy.

The average last frost date in Vancouver is about April 17. Hardy vegetables can be planted outside up to a month before the average last frost date. That means that hardy vegetable seeds or transplants may be planted by mid-March. Most hardy vegetables can withstand frost to about 26 degrees.

The other major factor determining when to plant hardy vegetable seed is soil temperature. Most hardy vegetables will germinate at a soil temperature of 50 degrees. A few, like lettuce, spinach and radish, will germinate at 45 degrees.

Soils that have lots of organic matter warm up sooner. Soils that are loose and open because they have been spaded or cultivated recently also warm faster. Raised grow box soils warm the fastest because they are usually a third or more organic matter.

I usually plant started plants of cabbage, broccoli, Brussels sprouts, kale and other vegetables in the cabbage family by late March. You can also plant seed of these vegetables at about the same time, but they won’t be ready to harvest until about six weeks later than the transplants.

Although you can also find transplants of other hardy vegetables, I prefer to plant virtually all of them from seed in the middle of March. I plant lettuce, spinach and radish seed in early March because they will germinate at lower temperatures. I make two or more sowings of lettuce, spinach and radish about four weeks after the first planting to extend the harvest period.

I plant seeds of beans and sweet corn in mid-April. I plant transplants of tomatoes and peppers in late April to early May. I use larger plants up to gallon size to speed up the harvest date.

I sometimes plant smaller transplants of eggplant, squash, cucumber and melon at about the same time. I often start seeds of these vegetables in early April, placing three seeds under a 1-gallon milk jug with the bottom removed to warm the soil. After seeds sprout, I remove the jugs in the daytime and replace them at night for frost protection for about a month.

Remember that average last frost date means half the time frost occurs after that date. So be ready to protect tender plants with blankets if frost warnings occur.

I have a seven-page leaflet on vegetable gardening. Send me an email if you would like a free copy.

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