Don’t let spring fever lead you astray

Mike McGrath,

Meet Mike in Fairfax this weekend!

WTOP Garden Editor Mike McGrath will appear Saturday and Sunday, March 10 and 11, at the Fairfax Home Show on the Annandale campus of Northern Virginia Community College. He’ll do talks at 1 p.m. and 4 p.m. Saturday, and noon and 2 p.m. on Sunday. Click here for more info.

Sowing grass seed now is like taking a hit with 19 showing

Brian in Alexandria writes: “I know that you preach never to sow grass seed in the spring as it will not survive the summer heat. Given that winter has been remarkably warm and weather teams are predicting a “cooler than average” summer, I’m wondering if the soil might be warm enough to germinate grass seed early enough to allow it to grow to a point where it will survive the summer months. Call me a gambler.”

OK, Brain, you’re a gambler. A very bad gambler, because spring seeding is a sucker bet when trying to establish a lawn of cool season grasses. That is the vast majority of lawn grasses in our region, including fescue, rye and bluegrass.

Now, you could get a soil thermometer and sow a turf-type tall fescue (the fastest germinating of the cool season grasses) the very first day the soil is warm enough. As a cool weather lover, however, the young new grass is going to naturally weaken as the weather warms. At the same time, all the warm season weeds that sprouted along with the fescue will be growing stronger, and by July you’ll be lucky if you have achieved a 50-50 split.

The smart money says to place your bet on one of the sure winners:

  • Lay sod now, which does great in the spring
  • Install a warm season lawn using zoysia grass sprigs or plugs. The only downside is that zoysia goes tan and dormant in cold weather
  • Sow cool season lawn seed in late August, when five will get you five. It will grow into a magnificent lawn.

Corn gluten: Soil temp and spreaders

Ernest in D.C. writes: “I understand that I should not apply corn gluten meal to prevent crabgrass until the soil temperature reaches 55 degrees. What method should I use: A drop spreader or a broadcast spreader? And approximately how much does a soil thermometer cost?”

Different manufacturers supply corn gluten meal with different particle sizes, so follow the directions on the package or consult the manufacturer’s website for those kinds of specifics.

A soil thermometer, which will allow you to spread your pre-emergent at exactly the right time — when the probe inserted four inches into the soil reaches that magical 55 degrees — will only set you back $10 or $20 for a simple mechanical version that looks like a meat thermometer. Spend a little more and you can get one that also measures the internal temperature of your compost pile. Then you’ll really be cooking.

Spring plants like cool temps — their seeds do not

JoAnn in Clarksville writes: “Since the winter has been so mild, can we plant spring vegetables early this year? I’d like to get a jump on the growing season if that’s possible. It hit 70 the other day, and it took everything I had to hold back from plunking pea, carrot and onion seeds in the ground.”

Do you feel a little better now that the freezer door has slammed shut on us again, with temps dropping into the teens tonight in some outlying areas, JoAnn?

We all have a killer case of spring fever this year, but the outdoor soil is still much too cold to germinate seeds. If you really want to scratch that itch, start some salad greens and such in containers indoors where the soil will stay warm, and then move the cold hardy plants outside a week or so after those seeds germinate.

And stay tuned. On St. Patrick’s Day, I’ll reveal a trick that’ll help you plant those peas no matter how cold the soil.

Pruning Roses: Sit on Your Shears Another Few Weeks!

Michael up in Columbia, Md. writes: “I’ve already got new shoots sprouting from my roses, which are still lengthy from last year. Can I prune them back now or is it too late? If it’s not too late, what’s the proper height for a new season?”

First of all, I have to congratulate Michael for not pruning his roses last year. Late season pruning can cause severe winter damage to all woody perennials, including roses. And speaking of winter, it’s not over yet! If you prune during a warm spell and then the temperature drops below freezing — as it will tonight — you can severely injure the plants. Wait until the nights are sure to stay well above freezing and then prune away. The final height you achieve isn’t important — that’s largely a matter of personal preference. What is important is that you remove any damaged or diseased canes and open up the centers of the plants to improve airflow. Be sure to remove and trash those prunings and any old mulch to prevent disease problems.

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