Garden News Issue 32

Garden News
Issue 32 • Seasonal tips and featured varieties coming to a retailer near you • May 14, 2010

Celebrate Our Last Frost Dates!

sun by karen lewisWelcome back to Garden News!  For our first issue of 2010, we’re celebrating a big day for gardeners coming up this weekend: May 15, also known as the average last frost date for many parts of the Northwest.  Until this day, we must restrain ourselves from planting out tender summer vegetables starts, but from here on out it’s time to keep an eye on the forecast and seize any sunny week as an opportunity to get seeds and starts in the ground.


The last frost date is the latest day in the spring that a particular area could expect a frost.  The average last frost date is the date by which the latest frost had occurred in half of previous years.  At our nursery in Cottage Grove, May 15 is the average last frost date.  But June 13 is the last frost date, the date from which we are (probably) guaranteed not to have frost.  (Planting directions are usually based on the average last frost date.)

The actual last frost date for each area varies from year to year, and the actual last frost date each year varies from place to place.  Even within a region, microclimates can influence frost dates a great deal.  To find average frost dates for your particular area, visit the National Climatic Data Center.

So the arrival of May 15 (or the average last frost date for your area) doesn’t always mean it’s safe to start planting out squash and cucumbers, beans and tomatoes.  It does mean it’s time to closely watch the weather and be ready to plant or sow if you see a warm week coming up.  For most of the Northwest, the forecast for the next week looks pretty warm and sunny – safe enough to try a first sowing of green beans, cucumbers, squash, or potatoes.  You could even risk a first sowing of melons or set out the tomatoes – especially if you can protect them for a few weeks with a hot cap or plastic hoop.


Luckily, while we’re waiting to sow beans or transplant peppers, we can enjoy two highlights of the spring vegetable garden: greens and alliums.

Those with the luck and/or foresight to start the garden early this year (or overwinter some hardy varieties from last fall) may now be harvesting buckets of kale, mustards, lettuce, spinach, radish tops, arugula, endive and other fresh, nutritious spring greens.  Alliums also thrive in cool winter and spring weather, with early chives and scallions (and possibly the last of the winter leeks, storage onions, or shallots) providing the perfect complement to all those greens.

We also introduced a series of walking onions (also known as Egyptian walking onions or topset onions) this year.  In summer, these hardy perennial onions grow tall stalks that produce clusters of spicy bulbils to use like pearl onions or in cooking.  In spring and fall, the greens can be harvested and substituted for chives or scallions.  If you leave a few of the bulbils unharvested, the stalks will fall over and they will root themselves, for a new crop next year.

If cold hardy veggies aren’t in your garden already, they can be planted any time.  In addition to the usual favorites, this season we’re offering a brand new vegetable called ‘Petit Posy’ Flower Sprouts.  A cross between Brussels sprouts and kale, this exciting new ornamental edible grows like Brussels sprouts, but produces colorful little rosettes of miniature kale leaves!  Tall upright stalks are covered in frilly purple and green bicolor leaves that can be steamed, stir fried, or tossed in salads for a beautiful, flavorful, and nutritious addition to your table. Read about it in this article at and Val Easton’s blog.

picotee kaleWe also have a new kale we’re calling ‘Dick’s Picotee Kale.’  A gorgeous ornamental edible, it was bred by Dick Degenhardt in Boskoop, Netherlands using a traditional form of propagation, cloning by root cuttings. ‘Dirk’s Picotee Kale’ adds interest to mixed beds or containers while providing a continuous harvest of nutritious, eyecatching greens for garnishes, salads, or steaming and stirfrying.  Plants like full sun and cool moist soil and are somewhat hardy (like dinosaur kale) to about 10 degrees F.


They may not be quite ready to go outside yet, but warmer weather means it’s time to start planning for  warm weather veggies – perhaps even potting them up to grow a little longer in a greenhouse or cold frame.

Sweet Potatoes – An exciting addition to our constantly expanding vegetable repertoire!  Native to the tropics, sweet potatoes usually need a long warm season to mature, but they can be coaxed to produce in the Pacific Northwest.  We’ve done the first part, by giving them a head start in 4″ pots.  Once air and soil temperatures are warm enough to set out pepper plants, you can transplant sweet potatoes into the garden.  Make sure they are in full sun, and use green or black plastic or cloth to hold heat in the soil around the plants.

An alternative is to plant them into black or dark plastic trash cans: fill the bottom third with soil, then transplant four 4″ pots into each can.  As they grow, place extra soil in around the plants, leaving 12 inches of foliage above soil level.  Water well about once a week as they grow, making sure the trash cans have drainage holes in the bottom.  To harvest, dump the cans out before the first frost.

sweet potatoes

Our sweet potato starts are ready now, and we’re offering over ten varieties in a rainbow of colors, including ‘Beauregard’ (red skin, orange flesh), ‘Centennial’ (copper skin, orange flesh), ‘Ivis White Cream’ (khaki skin, creamy white flesh), ‘Purple’ (purple skin and flesh), and ‘Violetto’ (purple skin, white flesh). We selected these varieties with the help of our friends Carol and Anthony Boutard of Ayers Creek Farm who have grown over 100 different types of sweet potatoes.

black sea manTomatoes – New varieties this year include ‘Black Sea Man,’ a richly colored Russian heirloom with flavor to match.  Warm mahogany fruits with olive shoulders display a glowing swirl of tie-dye colors when sliced, while their intense, creamy flavor is a hit in sandwiches or salads.  To our Believe It Or Not Vegetable collection, we’ve added ‘Reisotomate,’ whose curiously shaped fruits look like a cluster of mini tomatoes fused together to make one extravagantly lobed fruit. The name is German for “traveler’s tomato,” as you can pull off one lobe at a time for snacking on as you walk.  ‘Cherokee Green’ is a rediscovered heirloom with bold, complex, acidic flavor, while ‘Violet Jasper’ yields tons of small, smooth, round violet fruits streaked with green.

We’re also bringing back a few favorites from previous years, including ‘Moonglow,’ which produces brilliant orange globe-shaped fruits with fantastic sweet-tart flavor & smooth texture; ‘Black Krim,’ our favorite black tomato, whose violet-red, slightly flattened 4-5″ fruits with nearly black shoulders have intense, exotic flavor that’s been described as “smoky” or “salty”; and ‘Jaune Flamme,’ an exquisite French heirloom whose abundant clusters of 1½” apricot-colored fruits are wonderful for roasting or drying to enjoy long into the winter. See our lists of classic tomatoes and heirloom tomatoes for more info.

Previous issues of Garden News are in the Log House Library.