Binetti: Spring fever, chilly nights don’t mix

On GardeningMay 7, 2014 

May Day may scream that summer is near, but it is still too early in Western Washington to set out heat-loving plants such as coleus, marigolds, tomatoes, eggplant, cucumber starts and young squash seedlings.

Gambling gardeners will dig in and plant anyway because our climate is fickle and we just might enjoy warm nights and mild days through mid-May.

So what’s a gardener suffering a serious case of spring fever to do? Go ahead and purchase bedding plants, geraniums, zucchini starts, young tomatoes and all those other tender young things tempting you at the nursery. Then consider these ideas that will hedge your bets in case of a chilly May night:

1. Store new plants on a covered porch or patio for a few nights. This is called ‘hardening them off’ and forces tender greenhouse-grown plants to develop a tougher skin (OK, on a plant, this would be their epidermis), A drop in temp to, say 40 degrees, won’t turn those green leaves yellow or gray.

When you store plants close to the house you also keep them out of the strong wind and direct sun. Even sun-loving plants will suffer sunburn if they haven’t been allowed to gradually build up a bit of a tan.

Coleus and tomatoes are especially susceptible to sunburn, wind burn, spotting from rain drops and stunted growth if they are not allowed to get used to the cold cruel world in a gradual way.

2. Cover new plants with a sheet each night. Sometimes you just have to plant when you have time to plant — but what if a drop in temp or heavy rain storm is predicted right after you plant a flat of petunias into the ground or transplant your cucumber starts?

Recycle a lightweight bedsheet as a nighttime covering over tender seedlings at least for a night or two. Just remember to remove the sheet in the morning if the sun comes out.

3. Set tender potted-plants into a wheelbarrow or wagon. Finding the perfect heirloom tomato at a plant sale or an unusual yellow and white black-eyed Susan vine at the nursery means you will come home with tender plants that you just had to buy. A wheelbarrow or wagon makes a great home for these contained plants because you can wheel your tender treasures into the protection of a garage or garden shed at night. Just don’t forget to take them out for sunshine and fresh air in the morning.

4. Pamper tender plants with mini greenhouses. My favorite protection for tomato plants is to wrap bubble wrap around a metal tomato cage and secure with duct tape. This works much better than the plastic forms that you are supposed to fill with water. In our climate the sun does not shine hot enough in the spring to warm the water and release any heat at night. Bubble wrap is insulating, cheap and effective.

If you have small tomato or cucumber seedlings, you can make a greenhouse from a gallon-size milk jug. Just cut out the bottom of the jug and leave off the cap when you cover the transplants so air can flow. Soft-drink liter bottles also can be used as well as clear plastic cups turned upside down over tender young seedlings.

5. Put a tent over your pots. If you want to jump the heat gun and fill your patio pots with geraniums, petunias, begonias and other summer flowers you can create a simple insurance policy by using three sticks tied at the top to form a conical tent over your newly planted treasures.

You can even use supple branches from spring pruning shrubs to make this pyramid form. Then it will be easy to wrap the tent with bubble wrap, or drape a sheet over the supports if a storm is predicted. That also offers protection from sudden hailstorms. It will be easy to remove the supports once the plants are hardened off.

6. Plant tough plants that love our cool nights. You can add lettuce, peas, kale, cabbage and most herbs (except basil) to the vegetable garden now and don’t worry about protecting these cool season crops at all.

To fill your flowerpots without worry, pick cold tolerant alyssum, lobelia, euphorbia, dianthus, nemesia, dragon wing begonias and wax begonias. Some of the new petunias and mini petunias are also very adaptable to cold weather at night. Meet Marianne

Marianne will speak about gardening with wildlife at 12:3o p.m. Saturday at the Backyard Wildlife Festival at Tukwila Community Center.

More info: backyard wildlife festival.org.

Marianne Binetti has a degree in horticulture from Washington State University and is the author of several books. Reach her at binettigarden.com.

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