When Will Threat of Frost Pass So It's Safe to Plant Garden?

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METRO DETROIT, MI – Ready, set, dig.

Well, maybe not just quite yet.

The Old Farmer’s Almanac says the last date for a frost in Metro Detroit usually falls around April 22. That source says There’s a 50 percent probability that frosty weather is over until fall, when the first killing frost usually falls around Oct. 23.

But can you trust that?

Michigan State University is more conservative about the threat of a frost. There’s a 75 percent probability the last frost will occur on April 25, a 50 percent probability it will be May 3 and a 25 percent probability it will be May 11.

A frost isn’t something you want to risk with young garden plants.

A light freeze — 29 to 32 degrees — will kill tender plants, and a moderate freeze — 25 to 28 degrees will be widely destructive to most vegetation. And a severe freeze — 24 degrees and colder — well, you don’t want to know. (If you do want to know, expect heavy damage to most plants.

But if the gardening bug has bitten, there are tasks you can be taking care of in the garden right now, according to MSU. You can plant cool season crops like onions, beets, lettuce, spinach, carrots and radishes soon as the soil is dry enough. To test the readiness, take a handful of dirt in your hand and squeeze; if it crumbles when you open your hand, it’s ready for planting.

Here are the ideal planting dates from some common garden fruits and vegetables, according to The Old Farmer’s Almanac:

Green beans: Mid-May to mid-June

Beets: Mid-April through the end of June

Broccoli: April and May

Brussels sprouts: Mid-March through mid-May

Cabbage: April and May

Carrots: April, May and June

Cauliflower: Mid-March through mid-may

Celery: Mid-May through June

Corn: Mid-May through Mid-June

Cucumber: Mid-May through Mid-June

Garlic: October, November and December

Eggplant: Mid-May through mid-June

Kale: April and May

Leek: April and May

Lettuce: Mid-March through Mid-September

Melon: Mid-May through June

Okra: Mid-May through June

Onion: Mid-March through mid-June

Parsnip: Mid-April through mid-June

Peas: April through June

Pepper: May and June

Potatoes: April through June

Pumpkin: Mid-May through June

Radish: March through mid-October

Squash (summer): Mid-May through June

Sweet potato: Mid-May through June

Swiss chard: Mid-May through mid-August

Tomato: May and June

Watermelon: Mid-May through June

Image credit: Jo Ann Deasy Via Flickr / Creative Commons