Plant early with milk-jug mini-greenhouses

MOSES LAKE — Some plants are meant to be left in the ground through the winter, and now that it’s February and the ground outside is as hard as week-old peanut brittle, it’s a little late to be planting. Fortunately, there are ways to use milk jugs and even ice cube trays to get planting underway.

“Some seeds need to be frozen in order to split their outer shell,” said Valerie Parrott, president of the Columbia Basin Garden Club. “Things like carnations, they really need to be cold. So, you just fill your ice cube tray (with water), dump a few seeds in one, freeze them for two weeks, then you can go outside and plant them, and that will act the same as a cold stratification ... as if they had gone through a lot of hard freeze cycles.”

Once the two weeks are up, it’s time to upgrade the seeds’ accommodations a little, into plastic jugs. Milk jugs work well, or bottled water jugs, Parrott said, but it’s best if the jugs have a little opacity to them. Take off the lid and with a sharp knife, cut almost all the way around the jug, leaving just enough uncut at the base of the handle to form a hinge. Fill the bottom half with about four inches of pre-moistened – but not too wet – potting soil, punch a few drainage holes in the bottom of the jug and plant your seeds. Close up the jug and seal it with duct tape or packing tape and put it outside. The jug will act as a miniature greenhouse and leaving the lid off will allow a little moisture in. Don’t forget to mark what kind of seeds they are, Parrott added, preferably in more than one place because markings and tags sometimes come off.

“I do check once in a while,” she said. “If it looks dry I just put a spray bottle down there and give it a little bit of a spritz.”

When do you put the jugs outside? According to information emailed to the Columbia Basin Herald by WSU Grant-Adams Master Gardeners Terry Rice and Duane Pitts, start at the end of February with perennial and biennial seeds. Cold-hardy veggies, perennials and annuals should go out by the beginning of March, and frost-intolerant seeds like tomatoes, squash, gourds and beans can go out sometime in early March.

“In March and early April, you should start really seeing some pretty good growth,” Parrott said. “People do broccoli, cauliflower, tomatoes, you can do your tomatoes in here … strawberries are great to start winter sowing. Mostly any type of herbs, too; you can start all your herbs early, you can start onions from seed.”

The best place to put the jugs is in a south-facing of the yard or garden, she said.

A common mistake gardeners make in winter sowing is pessimism, Parrot said, filling too many jugs on the assumption that only a few seeds will actually sprout.

The kind of potting soil you use matters too, she said. Avoid the brands that tout extra moisture; the gardener can always add their own moisture if there’s not enough.

The last frost in the Basin is usually around mid-April, according to the WSU Master Gardeners.

“I will probably start taking (my plants) out the first week of April, unless things start getting too big,” Parrott said “Then I’m going to have to repot them and put them in my greenhouse. If you start seeing plants getting up to that first curve in the top (of the jug), then you need to probably get them out and transplant them. But normally I’d start at the beginning of April, potting up, getting ready or even moving out to the garden and covering with frost cloth.”

The Columbia Basin Garden Club will offer a winter sowing workshop Feb. 22, Parrott said. Anybody interested can bring their milk jugs, potting soil and seeds and club members will help them get their seeds ready. More information is available by calling 509-431-1879.