Video Thursday: Protecting plants with tunnels

Colorado Master Gardener Jackie Buratovich has gotten low tunnels down to an art in her yard.  Take a look at how she protects her plants in this video made with the Boulder Daily Camera newspaper (listen close, and you’ll hear the neighborhood children doing their best to distract the photographer).

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Icing Plants

 When you pick up a perennial this spring, check the tag to see where it was grown.  If it came from Oregon, chances are it was watched over by Jeff Stoven, who’s keeping a watchful eye on his charges during a cold snap that has tender plants at risk of freezing their buds off.

As the Head Grower for Bailey Nurseries in Yamhill, Stoven is responsible for over 100,000 potted plants.  As temperatures plunged to 18 degrees at the end of February, he sprang into action to keep the quarter-million dollar crop protected, not with row covers or tarps.  Instead, the blanket he swaddled them in was a coating of ice.

“Because our spring was so early and warm in February, the plants started to grow,” he said, “and now we’re at a critical time because it got really cold and we have to protect the new growth.”

Using ice to protect citrus crops in Florida and Georgia is common practice, but many don’t realize that the technique is widely used in the nursery industry as well.  As water changes to ice, heat is released and protects the plant from cold.  The trick is to keep the conversion of water to ice going for as long as you have cold temperatures.

“We come in just before the freezing temperatures and turn on the sprinklers a little at a time,” Stoven said.  “We get them a little wet, and ice forms around stems and buds.  We’ll continue to the water on and off for the next few hours, but we don’t want to overdo the amount of water, because we don’t want a huge glob of ice to form.”

Other techniques for plant protection vary, including lighting fires and moving the warm air with fans, or flying a helicopter low and slow over the field to move the air, but Stoven sticks to the proven method of icing in the plants.  You’ll see the results this spring in the garden centers.

Related Articles

• Protecting spring blooms from later winter snow, frost (cleveland.com)
• Cold Weather Tips for Your Plants – Before, During and After (hcgreenthumb.wordpress.com)

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Saturday matinee: How to protect your plants from frost

Sit back and enjoy tips on how to protect your plants from frost.  That is, if we ever get it – this video was produced for mid-September when Colorado starts having frost scares, but this year, Mother Nature just isn’t ready for the season to end.  Weather forecasts are showing a dip in nighttime temperatures headed our way, so if you’re not sick of the garden yet, get ready to do the frost protection two-step.  Produced by the Boulder Daily Camera.

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Frost protection

 Today’s post can be heard on the public radio show Crop to Cuisine, hosted by Dov Hirsch.

You can tell who the serious vegetable gardeners are.  They’re the people who construct the darnedest coverings to provide a few extra weeks worth of growth before the weather really warms.   Gardens start to look like a rock festival with all of the tents, tunnels, and jugs showing up.  

One gardener in Lockport, Illinois, a town just outside of Joliet, sent me photos of the prettiest seedlings I’ve ever seen grown at home.  Despite living in zone 5, he planted these out on April 13, a full month-and-a-half ahead of when we – also zone fiveish – put ours in the ground. 

Now, I’m not what you would call a competitive gardener – if others like to get their gardens in fast, that’s up to them.  But looking at the deep green, foot-tall plants this 74-year old gardener’s got in the ground made me pause in envy, and think “when I grow up, I want to be just like Jim Koski.”

As we head into May and you’re shopping for that special seedling, take a page from his book to keep your plants cozy in our unsettled weather, at least through frost date.  Jim tucked his into the ground with a combination of items; his objective is to warm the soil with sun in the day and give plants frost protection at night. 

  With a red plastic Automator tray – the product touted for channeling water and fertilizer to roots – to warm the soil, Jim breaks wind on his seedlings by wrapping their cages in stiff, black salt paper.  Chill breezes are a seedling’s enemy, but this method keeps his plants “nice and toasty.” 

I’ve seen many types of protective covers; a friend of mine firmly believes that Christmas lights hung inside a plastic tunnel are the best means of protecting plants from late frosts.  This makes sense to me.   By using one 25-light string of mid-size, non-LED (C-7) Christmas lights per four-foot-by-five-foot tunnel, gardeners can give an additional 6 to 18 degrees F◦ of warmth to plants and add that festive touch to a spring landscape. 

Constructing the tunnel isn’t difficult.  Space sturdy wire hoops at 3 to 5 foot intervals or closer if the location is windy. The hoops hold a cover of six-ml or thicker plastic that forms a tunnel along the bed. Weigh down the edges of the plastic by burying it a few inches into the soil on all sides, or staple the plastic to the sides of a raised bed box. Be certain to allow some ventilation with small, two-inch holes along the lower sides, or make a strip along the top that can be opened and closed.  To avoid overheating the seedlings, open the vents on warm days, but leave them shut on cloudy, cool days.

String the lights from the hoops to allow them to dangle slightly into the tunnel.  Use an outdoor-approved extension cord to run electricity to them, and you’ll have tomatoes to brag about weeks earlier than your neighbors (but most neighbors will take one look at those Christmas lights and assume you’re crazy, so won’t argue over whose tomato was ripe first anyway).

The most common frost protection is water walls, a tee-pee like ring of plastic tubes filled with water surrounding the plant.  This works on the principle of heat release when water changes from liquid to ice and can protect down to mid-teen temperatures. They’re helpful if you want to put your tomatoes, peppers, or eggplant into the ground before the end of the month, when the weather settles into warmth.

The trick to using the water walls is to pick a warm day, plant the seedling, position the water wall and fill it.  I find that using a watering can with a narrow spout helps to control the water when pouring into the tubes, or a hose end hand sprayer works well if the water pressure isn’t too high.

Give your seedlings a shot of starter fertilizer, or try Jim’s technique of spraying the plants with organic fertilizer.  He uses dilute fish emulsion or Sea Magic, a seaweed extract mixed into water, then spritzed on the leaves of the plants.  Your plants will be catching up to his, in no time.  

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Freeze predicted tonight

Are we ready for this again?  A light freeze is predicted for the Front Range tonight with temperatures expected to get down to 31 degrees F.  Because we did this dance last week, here is a repeat of suggestions for protecting your plants:

 If your winter squash, melons and pumpkins aren’t ripe, tent the patch with a cover of PLASTIC, not blankets.  It is fine if the vines die back; those fruits that have begun to ripen will continue to do so after we warm again.

If you plan on trying to tent your tomatoes, keep in mind that those which have started to color can take the cold temps under cover, but immature green tomatoes will stop development and never ripen.  Pick these today and enjoy them fried. 

Grapes need covering if you still have fruit on the vine.

Carrots, beets, parsnips and other root vegetables will be fine – no covering is necessary.  Potato vines will die off, but the tubers will be unharmed; plan to harvest those this weekend.  Lettuce, bok choy, leeks, spinach, brussels sprouts, and broccoli can take the cold.

Kale will sweeten with a bit of frost, so leave that out in the open. 

 If you’re not sick of the garden yet, cover your tender plants, such as peppers, eggplant or basil,  being sure that the covering does not touch the plant and extends completely to the ground.  The warmth of the soil will fill the covering like a tent, keeping temperatures just above freezing.  Cloth coverings won’t work because of the rainy conditions before the snow, so plastic is preferred.  Remove the coverings in the morning to allow the soil to warm again.

Perennials should have been hardening off over the past month in response to cooler nights and shortened days.  They don’t need covering.

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Snow forecasted for Front Range tonight

Be careful what you wish for.  In a grump after spending all day Sunday processing tomatoes (dehydrating, saucing, freezing), I blurted out “C’mon frost!”

Frost may not show up but his cousin, snow, is predicted for the Denver area tonight after midnight.  Rain mixed with snow and accumulations up to one-inch are expected, so pick your produce before dark.  If your winter squash, melons and pumpkins aren’t ripe, tent the patch with a cover of PLASTIC, not blankets.

If you plan on trying to tent your tomatoes, keep in mind that those which have started to color can take the cold temps under cover, but immature green tomatoes will stop development and never ripen.  Pick these today and enjoy them fried. 

Cover your tender plants,  being sure that the covering does not touch the plant and extends completely to the ground.  The warmth of the soil will fill the covering like a tent, keeping temperatures just above freezing.  Cloth coverings won’t work because of the rainy conditions before the snow, so plastic is preferred.  Remove the coverings in the morning to allow the soil to warm again.

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Cold temperature alert!

Gardeners, if you have tropical plants in containers or houseplants you grew on the patio, now is the time to bring those in for the night.  Temperatures are predicted to be 38 to 40 degrees tonight, far colder than those plants will tolerate.

The week long forecast looks to be a bit colder at night, depending on whom you believe, so toss a blanket and plastic sheet over any garden plants you’d like to save.  Remember, the warmth from the soil is what keeps the plants from freezing, so drape your cover all the way to the ground, anchoring it along the bottom so it doesn’t blow off.

If we continue to get rain squalls, blankets alone are not a good choice; once wet they no longer protect the plant.  Plastic over the blankets will work well.

Remember to remove these covers in the morning – it gets hot under the blankets and roasts those plants during the day.

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