Timing for planting seeds depends on soil temperature
Dear Helen: I’ve been waiting for weeks to seed some of the first coolseason vegetables in the open garden, but the soil has remains cold and wet. I’m thinking mainly of peas, and the root crop bed of carrots, parsnip and beets. How can I determine when to sow the seeds?
These are the vegetables I usually sow first, beginning with the peas and then the roots. In view of the previous two early, warm spring seasons I had been hoping for a February or early March seeding, but it’s been too cold. From what I’ve observed and am hearing, the season is three to four weeks behind. My forsythia didn’t start blooming until about 10 days ago.
The timing for planting seeds depends on soil temperature and moisture content. Wet soils stay cold longer, and working heavy, clay-type soils while they are wet only further compacts them.
Some very well-drained soils will likely have warmed enough to seed the vegetables you are mainly concerned with. In my light-textured, sand-based, fastdraining soil I’m recording early morning soil temperatures of around 6 C, up to 9 C at noon. Though the references I have indicate that an ideal germination temperature for peas is 24 C, the seeds can germinate in soil temperatures as low as 5 C. I don’t think I’ve ever waited for a temperature reading of 24 C to sow peas; however, I don’t like seeding into wet soils.
Soil temperatures for good germination of most rootvegetable seeds begin in the seven to 10 C range and go to 29 C. Lettuce will germinate at 5 C, while the ideal soil temperature is 24. Beans, a warm season vegetable (except for broad beans, a cold hardy type), need a minimum soil temperature of 18 C, while 27 C is ideal.
Tricks to hasten the advent of ideal germination temperatures include pre-warming the soil with clear plastic and placing a portable cold frame or row cover over the seeded area. Starting seeds indoors gets growth on the way while the soil warms enough for transplanting.
GARDEN EVENTS
Spring sale. The Peninsula Garden Club will host a Spring Plant Sale on Saturday from 9 to 11 a.m. in the Mary Winspear Centre in Sidney. Plants, at great prices, will include vegetable transplants and exotics. Also for sale will be books and garden items. Come early for the best selection. Dahlia sale. The Victoria Dahlia Society will hold its annual Tuber and Plant Sale on Saturday from 9:30 a.m. to 2 p.m. at Knox Presbyterian Church, 2964 Richmond Rd. Over 1,000 rare and exclusive varieties, all cultivated by local growers. Experts will be on hand to answer questions. victoriadahliasociety.org. Perennial exchange. Dinter’s Nursery, 2205 Phipps Rd. in Duncan, is hosting a Perennial Exchange at 9:30 a.m. sharp on Saturday in the nursery potting shed. Bring surplus plants and trade with other gardeners. Bring garden problems and questions to a Master Gardener Clinic from 10 a.m. to 3 p.m. Greenhouse gardening. Russell Nursery, 1370 Wain Rd. in North Saanich, is offering a free class on making use of a greenhouse in all four seasons on Sunday at 10 a.m. Space is limited. Reserve a place by calling 250-656-0384 or by email (russellnurseryoffice@telus.net). Include your phone number in the email. HCP workshops. The Horticulture Centre of the Pacific, 505 Quayle Rd. in Saanich, is offering the following workshops. To register, call 250-4796162. hcp.ca • Advanced Pruning, Saturdays, April 15 and 22, 9 a.m. to 12 p.m. This outdoor course will review basic techniques and teach advanced pruning strategies as you practise. Cost to HCP members $90, others $110. • Oval potato basket, Sunday, April 16, 9:30 a.m. to 5 p.m. This variation on a rib basket uses willow for the hoop and dyed reed and seagrass for weaving. HCP members $120, others $140. Shade ideas. Richie Steffen, curator for the Elisabeth C. Miller Botanical Garden near Seattle, will present Bright Ideas for Shade on Wednesday, April 19, 7 p.m. at the Horticulture Centre of the Pacific. With photography and commentary, Richie will focus on the best plants to turn dark garden spaces into shining oases. The talk is one of the Russell Nursery 25th Anniversary Speaker Series. Tickets cost $25 at the nursery or at russellnursery.com. Space is limited. Tickets need to be purchased in advance.