Ready for Frost?

Fall has officially arrived.  We are now a few days beyond the average first date of frost which occurs around September 20th.  While the forecast still shows several nice days ahead, that first plant-startling night of frost could be as soon as a week from now.   If you love your heirloom tomatoes and other tender veggies, you won’t want to lose them to the first frost because you weren’t prepared to protect them. Radiation frost is typical both at the start and end of the growing season.  It occurs on calm, clear nights that are without cloud cover that holds in heat.  These frosts dip only a few degrees below safe levels for plants and it is within this temperature range that gardeners can safeguard their plants. The starting point is to know which plants need protection from a light frost and which ones don’t. Plants that will survive frost include seasonal fall color flowers such as pansies, mums and asters.  They can take the frost and sometimes a freeze.   Hardy veggies on the frost-hardy list include root crops such as carrots as well as hardy leafy greens such as kale, spinach, chard and collard greens.  Winter squash, cabbage and broccoli will also survive frost.  Pumpkins themselves will be fine until a freeze, but the leaves won’t survive a frost and that also applies to winter squash. Most everything else out in the garden will need frost protection.

  • If you still have containers with petunias and other summer annuals, they won’t survive and need to be covered if you want to enjoy them a little longer.
  • All the tender veggies – tomatoes, peppers, tender greens and annual herbs – also need to be covered.
  • Typically, there are still many good growing days after the first frost and you can take advantage of them to keep the harvest ripening with the right precautions.

When protecting plants from frost, the goal is to hold onto the heat in the soil that was generated during the daytime.  The first step is to cover plants to retain warmth in the soil.  Do NOT use plastic – as plastic conducts cold into the plants and they will freeze where the plastic touches them.   Use special frost/freeze protection blankets from the garden center or use household fabric items you already have on hand such as sheets and blankets.  Large beach towels work well for covering containers. Place coverings low over the ground and spreading.  And remember that these materials need to be removed the next morning so that the soil can again recharge its warmth from the sun. Plants that already have cages around them can support the fabric.  But if there is no support, another useful item is staking material that will hold fabric above plants so they are not bent or crushed from its weight. Another useful trick for tomatoes is to wrap tomato cages with non-LED holiday lights.  Traditional lights are warm whereas LEDs are not.  Plug lights into an outlet with an outdoor extension cord and then wrap the cage with a fabric covering.  Your tomatoes will be nicely tucked in to survive a cold night.   Your kids will love the early holiday cheer – and your neighbors may think you’re nuts. But your tomatoes will live through the night!

Contact Designscapes Colorado at info@designscapes.org or 303.721.9003.

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