The USDA Zone info is a great tool for gardeners to help us determine your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Altoona you can estimate when it's possible to plant welsh onion by checking out the USDA zone info.

Planting Calendar for Welsh onion

Frost tolerance for welsh onion:	Tolerant of a very small amount of frost.
When to plant:	Up to 3 weeks before last frost.

Welsh onion are barely cold tolerant which means that you can start planting them slightly earlier than other frost tender plants.

The earliest that you can plant welsh onion in Altoona is March. However, you really should wait until April if you don't want to take any chances.

The last month that you can plant welsh onion and expect a good harvest is probably August. You probably don't want to wait any later than that or else your welsh onion may not have a chance to really do well. If you are starting your welsh onion indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

In Altoona the average date of last frost happens on April 15. In the coldest months of winter you can expect an average low temperature of -20°F.

Keep in mind that the actual date of last frost may not be accurate from year to year because it is based on the USDA zone info for Altoona and it changes from year to year. Since half of the time in Altoona last frost occurs after April 15 be ready to cover your welsh onion in the event of one of those late frosts.

USDA Zone Info for Altoona

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Altoona

You may be interested in your other planting guides for Altoona.