Heat alert, Carrot Day arrives; spring diseases

The first day of summer is here and it is drizzly and cool again, but there IS a forecast of warm sunny weather coming at week’s end. For vegetables, the forecast highs of 24-27C [75-80 F] for much of the region (hotter than that up the Fraser Valley), constitutes a heat wave. Plants have been growing for so long in cool, moist, cloudy conditions that leaf tissue is soft and unprepared for hot weather. Should the heat materialize, before you head out for beach or barbeque, take time to rig up shade on seedlings, seedbeds, cool weather crops (peas, lettuce, young plants in the cabbage family). Any plants with large, soft leaves (squash, beans, leafy greens) could experience sunscald injury, especially at the highest temperatures. So keep your shading materials handy (shade cloth, latticework, lace tablecloths) for rapid deployment and watch the weather forecast. We haven’t been thinking about watering until now, but don’t forget to check that soil isn’t getting too dry.

Everyone wants to know what the rest of the summer will bring…but who knows! The June 9 synopsis from the Climate Prediction Center and the International Research Institute for Climate and Society showed about a 50/50 chance that the La Niña weather pattern, which brings our coastal region stormy, wet, cooler weather, will continue through the end of the season…or not.

At the moment, where overnight temperatures have been sinking below 10C [50F], there are still some sad looking warmth-loving plants. In cool conditions, such plants grow slowly and don’t take up nutrients at the rate they would in warmer weather. Despite what should be enough nitrogen and other nutrients in the soil, they may look deficient, with leaves lighter green or yellowing or even turning purple or brown. In warmer, sheltered gardens, warm season plants have been doing well, but where it has been cooler at night (cold valleys, high elevations, close to the ocean), these plants are struggling. There are also notable difference between varieties, with tomatoes bred for long hot summers (Brandywine, San Marzano paste, etc.) looking worst and early varieties suited to the Pacific Northwest (Stupice, Oregon Spring, Altai varieties, cherry tomatoes) doing better. In my garden, winter squashes are still lagging behind summer squashes, which have taken off, and cucumbers are still not certain whether or not they wish to go to the effort of producing a crop. Plants that have been doing poorly won’t handle a rapid change to hot weather so it would help to shade them for a few days, at least in the hottest part of the day.

Male and Female Squash Flowers

Don’t try feeding liquid fertilizer to green up struggling warmth-loving plants at this point: hold off on until there has been a week or two of summer weather, then see how the new growth looks. If the newest leaves are still pale, rain could have leached the readily available nitrogen from the soil, and it might be necessary to use liquid fertilizer (fish fertilizer, liquid from soaking compost overnight in a bucket of water, etc.) to give them a boost for this season.

Beans? The soil has been too cool to for good germination of beans until lately. If you seeded beans outdoors with poor results, try again, with early varieties (i.e., 55-65 days to harvest) as these still have plenty of time to produce a good crop this season.

When to mulch? I have been leaving the soil bare around my vegetables to allow it to dry out and warm up as much as possible. Of course, that means doing more hand weeding than usual since mulches are a great at weed suppression. Once a summer weather pattern has set in and it has been warm and dry for a week or two (she said, optimistically) I will start mulching. If hot weather arrives before the mulching is done, seedlings and young plants are top priority to shade: their roots are close to the surface and their leaves are too small to shade the soil so roots can be injured or killed by heat.

Are your squash plants big enough? A squash plant has to grow a good set of leaves before it can carry fruit. Once a plant is about a foot and a half across, that seems to be sufficient. If yours are not that big yet, pick off flowers until the plant grows more leaves (you can eat the flowers in salads, stuffed, fried, etc.). We have until the end of July before most winter squash fruit must be set in order to have enough time to mature. Hand pollinate flowers in cool or wet conditions when pollinators are not active; even in good weather I still hand pollinate to ensure fruit set. To do this, pick a male flower from the plant, peel back the petals and tap the pollen onto the centre structure in a female flower. Female flowers always have a tiny fruit just behind the flower, whereas male flowers have lots of yellow pollen in the centre and the flower stem is straight, without a tiny fruit below the flower. Check plants daily: squash flowers open early in the morning and only last for a day.

Carrot Day arrives. Planting for winter harvests really gets underway in July. Long time readers will know that July 1st has always been Carrot Day at my house—the ideal date to sow carrots to be harvested all winter. Other crops to sow in early July include beets, rutabagas, endive & radicchio, Swiss chard, kohlrabi. You may have some of these in the garden already, but those may be eaten up or overmature by October. Planting more root crops in July allows them to reach maturity just as the growing season ends. Although chard, kale, collards started this spring will yield right on through the winter, you probably need additional plants for winter harvests to allow for the fact that leaves don’t grow back in the winter as they do in summer.

For a printable planting chart for the south coast, see. The planting ‘windows’ shown on that schedule are about 2 weeks long: sowing any time in the two week period usually works for most gardens in this region. That said, this year, given the weather uncertainty, I am sowing my winter crops on the early side of the planting windows listed on the chart to make sure plants have enough time to grow.

Slower maturity of onions, garlic and other crops in spaces you planned to put winter crops in July may jam up your winter crop schedule this year. It is essential to start winter crops on time because we run out of growing season, but to make the schedule work, you may have to start seeds in flats or in a small section of a bed, transplanting seedlings into the main garden as spaces open up. Or buy plants from local sources (Chorus Frog Farm on Salt Spring, Russell Nursery near Sidney, Victoria Compost Education Centre sale on August 6th). In my next message I will list where you can get winter veggie starts. If you know of an organization that will have these plants for sale, please let me know.

Disease roundup: Long story, short: There is a huge amount of fungus amongus due to the perfect conditions we have had all spring for spread of fungi (and bacterial pathogens, too).

Apple scab has been severe on susceptible varieties (e.g., Gala, MacIntosh, Cox’s Orange Pippin). Infections result in brown splotches on leaves, death of flowers, spots on fruit. Even resistant varieties are showing some scab infections on leaves and it remains to be seen the degree of infection on fruit. There is not much that can be done at this point, but when you are thinning apples in a few weeks, the worse affected fruit will be the ones to pick off. A few spots on the skin are not a problem and the apple is perfectly edible, but severely infected fruit cracks and can’t develop properly.

On Salt Spring there is a widespread occurrence of a weird disease of plums, called plum pocket, which causes the fruit to become elongated and rough-skinned. This pathogen attacks the fruit, but is not inside the tree, therefore if you remove and destroy all affected fruit now, the crop from the same tree next year may be unaffected.

Garlic/Allium rust is rampant as are other rusts. Fortunately, Allium rust doesn’t seem have a big impact on the garlic crop (bulbs may be a little bit smaller) and because it isn’t on the bulbs, you can use your own garlic for fall planting.

Anniversary! This month I reached my 8000th subscriber to this newsletter—coincidentally it was someone I met through a previous job. I felt like we should have had balloons and party hats! When I started sending these messages to a few friends on Salt Spring at the end of June in 2008 it was to remind them to sow carrots on July 1 for their winter harvest. I had no idea these messages would eventually go out to so many gardeners on both sides of the border.

Upcoming talks open to the public:

Wednesday, July 13, 6:30 - 8:30 pm. Resilient Gardens for a Changing Climate via Zoom for Transition Salt Spring. Learn how extreme weather affects plants, including trees, and how to design resilient food and ornamental gardens that help plants survive our changing weather patterns. Discover the important role gardeners can play in mitigating greenhouse gas emissions, including designing landscapes to capture carbon. Register here.

June 22, 2022 7:38 AM