Some plants are still recovering from the damage done by the extreme heat at the end of June (others, such as cucumbers, corn and sweet potatoes are growing like never before!). It sometimes takes awhile for heat damage to leaf and fruit cells to become visible. A week or two after high temperatures, tan or yellow areas on tomatoes, peppers and tree fruit and blackened or shriveling areas on leaves were still developing and might have been mistaken for disease. Sunscald on a few of my apples and pears is just now showing up as yellowish spots on the side of the fruit facing the sun. Heat injury to raspberries appeared as patches of white or tan drupelets (those little globes that make up the berry) on maturing berries, while younger berries simply shriveled up. Some tomatoes, peppers, cucumbers, and beans lost the cohort of blossoms present during the heat wave and that loss is now being seen as a period with scant fruit. But blossoms that opened after the heat wave are fine and will produce normal fruit. There is no need to remove heat damaged leaves as any green areas left are still feeding the plant, but you may as well pick off sun scalded fruit since it won’t ripen properly.
The shade cloth, bedsheets and lace tablecloths pressed into service in various gardens saved the day for many crops. If you lost plantings, however, you still have time to re-seed some things if your plants died: bush beans, heat tolerant varieties of lettuce, small varieties of cabbage (varieties with 45-50 days to harvest), plus there are many fall and winter crops that we usually sow at this time of year anyway (see below). If you had plants that suffered heat damage, be prepared before the next heat wave with additional shading, irrigation and mulching. The value of mulches in keeping soil cool was certainly shown in gardens without mulch, where plants died despite being well-watered because the soil simply got too hot for the roots.
Planting for winter harvests: Until early August, you can sow seeds of kale, collards, daikon & other winter radishes, broccoli raab and the many hardy leafy greens (mizuna, leaf mustard, leaf radish, mustard spinach/Komatsuna, arugula) and Chinese cabbage (Joi choi, bok choy, Napa cabbage, etc.). These are all in the cabbage family and susceptible to attack by cabbage root maggots. Not only is this pest always more numerous in late summer, but with the warmer weather this year, there may be an extra generation, resulting in a whole lot more root maggots attacking plants. Cover root crops and leafy greens in the cabbage family with insect netting or floating row cover from the time of sowing until late October to prevent root maggots from making a mess of the root.
The soil is really warm and dries out fast right now so don’t forget to shade seedbeds until germination to keep soil cooler and evenly moist. You can lay shading materials on top of the insect netting over cabbage family beds. For a week or so after they come up, shade tiny seedlings in the heat of the day and also shade young plants during heat waves. People have asked me about just leaving the shading materials in place for the rest of the summer, but most plants won’t get enough sun to grow well if completely covered. Shading that filters just the hot afternoon sun, while letting in full morning sun, could be left in place. Lettuce can get by with less sun than other vegetables and could stay under partial shade that doesn’t block more than 50% of the light.
If you can find starts of winter broccoli, winter cauliflower, cabbage, as well as any of the other plants listed above, they can all be planted now. Sources that grow their own seedlings and have the ‘right stuff’ for winter gardens, include: Russell Nursery, 1370 Wain Road, North Saanich and Chorus Frog Farm stand, 263 Rainbow Road, Salt Spring. On Saturday, Aug. 7th the annual sale for winter veggie starts will be at the Victoria Compost Education Centre, 1216 N Park St, Victoria. Other local garden centres also carry vegetable seedlings at this time of year and the varieties of chard, kale and leafy greens available are mostly fine for fall and winter harvest. All too often, however, outlets that get their seedlings from wholesale suppliers don’t have the right winter broccoli, winter cauliflower or frost-hardy lettuce varieties. Although you may see Brussels sprouts seedlings for sale now, it is too late now to plant them for a successful crop.
Other July tips:
Irrigation: If your watering regime is adequate, the fruit on zucchini or cucumbers has straight sides, without ‘waistlines’. Narrower places in these fruit show there was a period when the water supply wasn’t quite sufficient.
Squash pollination: Winter squash fruit must be set on the vines by the first week of August to have enough time to ripen fully on the plants. That means making sure female flowers opening in the next 2 weeks get pollinated. Don’t count on insects getting the job done these days so you should hand pollinate. Every morning check plants for newly opened flowers: male flowers have a straight stem behind the flower and female flowers have a miniature fruit behind the flower. Pick the male flower, peel back the petals and gently tap the pollen from that flower onto the centre of the female flower (one male flower can be used to pollinate several flowers). Flowers only last a day and pollinating is best done in the morning. There are 3 squash species groups planted in this region: Cucurbita pepo, C. maxima and C. moschata. If you know the species group of your squash varieties you can mix and match flowers within the group. So, for example, you could use a zucchini male flower to pollinate an ‘Acorn’ or ‘Delicata’ or ‘Festival’ female flower. Don’t mix butternut flowers with other kinds of squash as only butternuts are in the C. moschata group. If it doesn’t say on the seed packet under the variety name what group it is in, check seed catalogue descriptions.
Pests du jour:
Tent caterpillars: Egg masses are being laid this month on trees, especially on apple, but they won’t hatch until next spring (that species only has one generation per year). If you happen to see the eggs now, of course pick them off, but there is no hurry. You will be able to make a thorough inspection of branches for egg masses this winter when leaves are off the trees. The masses looks like hard brown foam, about the size of a small fingernail.
Cabbageworms: The heat wave at the end of June accelerated the emergence of White Cabbage butterflies (often erroneously called “cabbage moth”). These lay eggs on cabbage crops and become those velvety green caterpillars, AKA Imported Cabbageworms. The result of this timing was a lot of damage on the small seedlings of winter broccoli, cauliflower, kale, etc. we are now planting for winter harvests. With the heat this summer we can expect more generations of species, such as this one, that have multiple generations per season. Keep checking cabbage family seedlings for eggs and caterpillars and pick them off. If you have large plantings with a lot of caterpillar damage, then as a last resort you may want to spray with a products that contains BTK (Bacillus thuringiensis), such as Safer’s Biological Insecticide. Gardens with lots of flowers to attract the many insects that attack cabbageworm often don’t see enough damage on large cabbage family plants to bother with control efforts, but vigilance to prevent damage on small seedlings is a good idea.