Before planting it is a good idea to find your USDA Zone info to determine your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

In Amsterdam you can figure out when it's a good idea to plant tree onions by using the USDA zone info.

Planting Calendar for Tree onions

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

Tree onions do ok in mild cold which tells us that you can plant them just a tiny bit earlier in the year than more sensitive plants.

The earliest that you can plant tree onions in Amsterdam 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 tree onions and expect a good harvest is probably August. Any later than that and your tree onions may not have a chance to really do well. If you are starting your tree onions indoors then you might be able to get away with starting them a few weeks earlier.

Last Frost Date

The average date of last frost is April 15 in Amsterdam. You can expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Amsterdam may not be accurate from year to year the actual date of last frost can change quite a bit from year to year. Half of the time in Amsterdam it frosts late in the year after April 15 so be sure to be ready to protect your tree onions in the event of a surprise late frost.

USDA Zone Info for Amsterdam

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Amsterdam

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