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Don't let spring fever ruin your garden or your lawn

Friday - 3/1/2013, 6:16am  ET

Pre-sprout those pea seeds indoors and plant them around St. Patrick's Day. (Thinkstock)

Meet Mike McGrath in Fredericksburg. He will appear at the Fredericksburg Home and Garden Show at the Fredericksburg Expo Center. March 15 to March 17

Mike McGrath,

Spring fever case #1: Don't sow seeds outside yet

Tina, who cares for plot 105 in the Newark Street Community Garden, has a bad case of spring fever. She recently emailed her fellow gardeners: "The high temperature this Saturday is supposed to be 45 degrees! Is anyone else planning to get out there and prepare their planting beds? I've heard that we can direct seed spinach and peas already!"

Whoa there, girl. A high of 45 degrees is still pretty chilly, and the soil temperature is much colder - way too cold for germination. Those poor seeds would just rot. And we're going to drop down into the bone chilling 20s tonight.

You can start your first runs of lettuce and spinach indoors now for planting outside a few weeks from now. The young plants don't mind weather that's too cold to sprout seeds. And you can pre-sprout those pea seeds indoors in a few weeks and plant them outside around St. Patrick's Day. We'll provide details next week, But direct seeding time in the naked soil is still a ways away.

Spring fever case #2: Corn gluten timing - look to the bay

Barbara in Springfield writes: "You recommend spreading corn gluten meal as a natural pre-emergent herbicide when the local forsythia begin to bloom. But with the odd, warmer than usual weather we've been experiencing, my crocus and tulips are already several inches tall. I'll bet that if I had forsythia, it would be budding. Is it time to use the corn gluten now? Or am I overeager?"

We're all overeager for the lawn and garden season to begin, Barb. The secret to successfully applying any pre-emergent to prevent summer crabgrass is to wait until the soil temperature reaches 55 degrees, measured 4 inches down, and that's still a ways off. If you don't have forsythia, look to your local red buds their first blooms are an ever better timing cue for corn gluten meal application.

Now, we heard from many listeners on this topic, including Mark and Cecilia in Alexandria, who write: "The weather is getting warmer and many plants are beginning to come up. Is it too early to put down corn gluten to prevent summer crabgrass?"

Yes, but now is a good time to either buy your CGM or locate a reliable source so that you'll be ready to spread it when those soil temperatures reach that magic 55 degrees.

One way to tell for sure when that time is approaching is to buy a soil thermometer. They are inexpensive and will serve you well for many planting needs.

Another trick: follow the temperature of the water in the Chesapeake Bay. Really. I recently spoke with Bob, a dedicated master gardener in Maryland, to ask if any local websites kept track of soil temperatures, and he explained that the bay water temperature closely mimics the soil temperature in our region. The water temp Thursday was a chilly 40 degrees.

Now that number is going to be most accurate for Maryland soils. You can add a few degrees if you live in a local hot spot like in D.C. or the southern reaches of WTOP's listening area.

The cure for spring fever is just a train ride away

I tell ya, I got so many spring fever emails from our listeners this week, I had to feed my computer chicken soup and Advil. Slow down, people. We are still far away from planting time.

So cure your craving for green by visiting the National Arboretum, the U. S. Botanic Garden or the Philadelphia Flower Show. The world's biggest and best indoor show opens this weekend at the Pennsylvania Convention Center and goes through Sunday, March 10. It's an easy Amtrak ride away.

This year's theme is "Brilliant!" It is an over-the-top look at the great horticulture of Great Britain. Imagine the title as being voiced by Eric Idle or John Cleese. I sneaked inside during set up and saw a huge replica of Big Ben, a great Alice in Wonderland garden that had beautiful metal sculptures of the characters as they were portrayed in the classic John Tenniel illustrations and the legendary clematis breeder Raymond Evison personally trailing some of his stunning specimens into the limbs of trees and shrubs just the way he recommends you grow your clematis. And that's just a small sample of the 20 acres of amazing displays.

I'll deliver my annual Philly flower show lecture at 1 p.m. Wednesday. You'll find all the details here.

Sod those bare spots, Bob!

Bob in Northern Virginia writes: "I have two bare spots in my yard circular areas around five feet in diameter where utility work had to be done. I know you say to only plant grass in the fall, but is there something I can plant in the spring to hopefully green up those areas at least until the fall, when I can do something more permanent?"

Absolutely, Bob. Now, if you have a bluegrass lawn, just be patient. It will fill itself in. If you have fescue, which doesn't spread, take some samples of your grass around to garden centers and find matching sod. Grass seed doesn't take in the spring, but sod does great.

And if it turns out that the sod doesn't quite match up perfectly, you can remove it and sow new grass seed successfully anytime from mid-August through September.

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