Vegetables for early spring

Preheating soil for the spring garden

Some nice info from http://www.waldeneffect.org/

The main difference between planting in early spring as opposed to after the frost-free date is soil temperature — cold ground makes seeds rot before they sprout.  Luckily, there are several methods of heating up the soil, ranging from the simple to the complex.

Rake back the mulch.  I’m assuming you’re working with a no-till garden, mulched heavily for the winter to keep weeds from taking over.  (If not, you’re going to have trouble planting early in the spring since your ground will probably be too wet to till, sometimes until June.)  While mulch is extremely handy during most of the year, the coating of organic matter acts like a layer of insulation in early spring, preventing the lengthening days from warming the ground.  The solution is simple — rake back the mulch.  I usually pull my spring mulch to the sides of the beds a week or two before planting each one.  That way, weeds don’t have time to grow, but the soil gets a chance to warm up.  Once the seedlings are a few inches tall, you can push the same mulch back up around their ankles, preventing competitive weeds from outgrowing your vegetables.Add dark organic matter.  You’ve probably noticed how wearing a black shirt in the sun heats your body up quickly.  You can put the same science to work in the garden by topdressing your beds with a layer of dark-colored organic matter.  Good compost, well-rotted manure, or even biochar can work.  For more extreme soil preheating, you can lay down a dark sheet of plastic on the soil, but be aware that this technique can kill soil microorganisms.Erect a quick hoop.  The quick hoops you built in October are easy to move to a fresh plot of land to create mini-greenhouses on top of your spring beds.  Putting up a quick hoop a week or two before planting can warm the soil by several degrees.

Also as a side note these quick hoops with some minor changes can also be used for a chicken run to put between your rows and allow your chickens to weed your garden for you.

hoops

You probably noticed that each of these techniques shares two factors — sun and time.  Your soil will naturally warm up as spring advances; you’re just trying to expedite the process so you can jumpstart the garden year.  To eat from your garden as soon as possible, combine all three methods and plant seeds as much as three months before your frost-free date.

 

Even under quick hoops, you won’t want to plant frost-sensitive vegetables like tomatoes and cucumbers anytime soon.  However, there is still a wide selection of crops to choose from for your spring garden.  I’ve highlighted the easiest ones in the chart below.

Vegetable Start from: Notes
Beets Seeds Beet seeds can sometimes be difficult to germinate.  As with other root crops, beets need loose, loamy soil.
Broccoli Transplants The more advanced gardener can start her own seedlings either inside or in a quick hoop.  Otherwise, buy sets from the local feed store when night temperatures have risen into the high 20s to low 30s Fahrenheit.
Brussels sprouts Transplants The more advanced gardener can start her own seedlings either inside or in a quick hoop.  Otherwise, buy sets from the local feed store when night temperatures have risen into the high 20s to low 30s Fahrenheit.
Cabbage Transplants The more advanced gardener can start her own seedlings either inside or in a quick hoop.  Otherwise, buy sets from the local feed store when night temperatures have risen into the high 20s to low 30s Fahrenheit.
Carrots Seeds Well-drained, loamy soil is mandatory.  Carrots are slow-growers, so weed carefully to give the seedlings breathing room.
Cauliflower Transplants The more advanced gardener can start her own seedlings either inside or in a quick hoop.  Otherwise, buy sets from the local feed store when night temperatures have risen into the high 20s to low 30s Fahrenheit.
Collards Seeds Spring greens are some of the easiest vegetables to grow.  In addition to collards, spinach, and Swiss chard, consider trying some Asian greens for variety.
Leeks Seeds Leeks take a long time to grow, so I generally prefer the perennial Egyptian onions instead.  As with other root crops, leeks need loose, loamy soil.
Lettuce Seeds Leaf lettuce is my earliest harvest of the year because I always plant it under quick hoops.  You can cut leaves within a month of planting, but be sure to seed a second bed as soon as you start eating the first — lettuce becomes bitter within a few weeks of first harvest.
Onions Seeds, sets, or transplants. Getting your onions to germinate out in the cold can be a bit tricky, so you may choose to start them inside or under quick hoops to ensure they have time to grow before summer heat stunts them.  Select a variety appropriate for your day length (short day in the south and long day in the north.)  Many gardeners simplify planting by buying sets (tiny bulbs) from the local feed store, but onions grown from sets usually don’t store well.
Parsley Seeds Parsley is grown very similarly to carrots, but you pick the leaves a few at a time for the next year rather than digging up the root.
Peas Seeds Soak your seeds overnight before planting to ensure they sprout quickly.  Erect a trellis for them to grow on.
Potatoes Cut up pieces of potato, each with two eyes Hill up your potatoes by adding soil or dirt extending a few inches up the growing stem once the plant is about eight inches tall.  This prevents the new tubers from being exposed to sunlight and turning green.  If you’re planting early into cold soil, consider cutting your seed potatoes a few weeks in advance and laying them out in a bright spot so they’ll presprout.
Radish Seeds Some gardeners plant radish seeds in their carrot rows.  The radishes come up quickly and mature before they compete with the slower-growing carrots.
Spinach Seeds I find that spinach plants usually bolt in the spring, so I generally focus on other varieties of leafy greens.
Swiss chard Seeds Swiss chard seeds can sometimes be difficult to germinate, but otherwise Swiss chard is perhaps the easiest green to grow and will keep producing all summer.
Turnips Seeds Like other root crops, turnips prefer loamy, well-drained soil.

The raw beginner should start out with collards, lettuce, peas, potatoes, radishes, and Swiss chard.  Second year gardeners might add broccoli, carrots, and parsley.  But ignore my advice if you love beets and hate lettuce — plant what you like to eat!

When to plant spring crops

Soil thermometerEvery winter is a little different, so I use a soil thermometer to keep an eye on the temperature of the soil and plant accordingly.  The thermometer pictured here is actually a meat thermometer, bought for less than $10, but it works just as well as the more expensive soil thermometers you’ll find in gardening stores.

To check the soil temperature, get up early before the sun has hit the ground and insert the thermometer into the ground.  Wait a few minutes, then take a reading.  If you have garden areas that are more sunny than others, you’ll want to test the soil temperature at several places–I usually find that our soil is two to five degrees colder in the shade of our hillside compared to in the sunnier parts of the garden.

The table below lists the germination temperatures for common spring crops.

 

Vegetable Minimum temp. (degrees F) Optimum temp. (degrees F)
Beets 40 50-85
Broccoli 40 45-85
Brussels sprouts 40 45-85
Cabbage 40 45-95
Carrots 40 45-85
Cauliflower 40 45-85
Collards 45 70-75
Leeks 40 70-75
Lettuce 35 40-80
Onions 35 50-95
Parsley 40 50-85
Peas 40 40-75
Potatoes 45 60-70
Radishes 40 45-90
Spinach 35 45-75
Swiss chard 40 50-85
Turnips 40 60-105

In most cases, you can get away with planting once the soil has reached the minimum germination temperature, but don’t plant your seeds if a cold spell is going to set in within a couple of days.  You should also be aware that some vegetables will give you spotty germination until the ground was warmed up closer to the optimum temperature — you might want to double your seeding rate to ensure a good stand if planting near the minimum.  Once a seed has sprouted, it’s less sensitive to cold soil, so expediting germination by soaking your seeds overnight before planting can also help.

To plant earlier than cold soil will allow, many gardeners are tempted to start seedlings indoors.  However, unless you have grow lights or a heated greenhouse, I recommend that beginners stick to growing their plants entirely in the earth for the first year.  A quick hoop might be enough to let you plant a couple of weeks earlier than you otherwise could have, then you can transfer the same protection to a new bed in April to jumpstart your summer garden.