Baby lettuce growing in a cold frame.

When I worked at a plant nursery, early spring was naturally the best season for business, with sun-deprived customers piling carts with heady optimism, hoping to beat their neighbors to the first veggie harvest.

And every year, despite our earnest warnings, we’d have an opportunity to sell some of those plants twice, because inevitably they’d get zapped by the freezing weather nobody wanted to admit was still coming!

If you just can’t wait to get to work in the garden this spring, here are a few secrets for getting a successful head start.

It’s All About Temperature

Air and soil temperature are the critical elements when planting a spring garden. For example:

• Cool-season vegetables need daytime temps in the 60s F and nights in the 40s F with an occasional light frost.
• Warm-season vegetables need daytime temps in the 70s-80s F with nights above 50° F, and they don’t tolerate frost.
• Planting seeds depends more on soil temperature than air temperature. If the soil can be warmed enough for the seeds to germinate, the growing plants may tolerate cooler air temps.

To get a head start in the garden, you’ll need to understand the temperature requirements of your plants, as well as the average spring planting time for your region. Armed with this information and a good thermometer, you can try some of these tips to help Mother Nature warm things up more quickly.

Containers are easy to bring indoors in cold weather.

Outdoor Early Planting Tips

Here are some tips to take advantage of the sunny days in early spring:

• Build a Cold Frame: A cold frame is a simple, low wooden frame with a glass or clear plastic top. It’s placed over seedlings in the garden or over a raised bed to give protection from those last frosty nights in early spring. Sort of like a mini-greenhouse, a cold frame keeps the air and soil inside about 5-10 degrees warmer than the surrounding garden to give you about a month head start on spring.
• Use Containers: Plant early veggies and flowers in containers that can be moved indoors at night and on chilly days. Try this tomato wagon for an easy moveable garden.
• Warm the Soil: Use black plastic, row covers, or solar plant cones to warm up your garden soil and make spring come early to your garden! Plastic helps hold in the sun’s heat, and you’ll get the added bonus of killing some of the weeds and pests under the plastic. Plan on a month of preheating for about a month’s head start. After preheating, you can remove the plastic or simply cut slits for your plants, leaving the plastic as mulch. The warmer soil will help seeds germinate outdoors, but make sure the nighttime air temperatures are above freezing before planting summer veggies.
• Add a Hotbed: You can purchase heating elements to turn your cold frame into a hotbed, or use the traditional manure-heated hotbed technique. A heating element allows you to have more control of the soil and air temperatures, allowing for seed planting and a head start on summer veggies like tomatoes and squash.

Start seeds in a sunny windowsill or under grow lights.

Indoor Gardening

Here are some tricks to take advantage of sunny windowsills:

• Start Seeds Indoors: By the time the soil is warm enough to plant seeds outdoors, you’ve already missed some growing time. By starting seed flats in a sunny window, you can have seedlings ready to transplant by the time the weather warms up.
• Indoor Containers: Herbs and salad greens are easy to grow indoors in the winter, and you can simply snip off leaves as you need them. Indoor hydroponic systems go a step further to provide a sophisticated growing system for year-round vegetable harvests.

Greenhouses can provide year-round gardening.

Greenhouses

If you’re dead-set on gardening year-round, and you live in areas with freezing winters, you’ll have to create an artificially heated environment for tender plants. A greenhouse is a great way to extend the gardening season, with several choices:

• Unheated Greenhouse: Made of insulating glass or plastic, unheated greenhouses function like a large cold frame, giving only frost protection and few weeks’ head start.
• Cool Greenhouse: Are minimally heated to keep temperatures above 40° F, allowing you to grow cool-season vegetables all winter long and to get a couple months’ head start on warm-season vegetables.
• Warm Greenhouse: Hothouses keep temperatures above 50° F, allowing ambitious gardeners to grow summer veggies and herbs even in the dead of winter.

Further Information

• How to Protect Your Garden from Frost and Freeze
• How to Determine Spring Planting Time for Your Garden
• Using Garden Fabric (Row Covers) (Gardener’s Supply)
• Greenhouse Growing

Tags: , spring