Summer seeding produces zucchini to harvest in fall
Dear Helen: My young zucchini plants are doing well, but I am thinking about their usual pattern of developing powdery mildew in late summer. Would a second seeding work for young, productive plants to succeed the older, mildewed ones?
S.L. Every summer I make a second seeding, usually indoors in July, for transplants to set out in early August. This timing gives me young zucchini to harvest in September and October, when spring-sown zucchini plants are coming down with powdery mildew on their older leaves.
Exactly when in July you seed, outdoors or indoors, will depend upon the earliness of the variety or varieties you are growing, and your garden’s growing conditions.
Seed packages indicate a “days to maturity” number. That number gives a relative indication of the time it will take from planting to harvest. For zucchini, the number is from transplanting. Among zucchini varieties, it’s a good idea, for the July seeding, to select an early variety.
My garden, which is partly shaded by tall forest trees on a neighbour’s property, does not yield the speedy growth typical of fully open sites with all-day sun exposure. For that reason, I seed indoors in the early part of July. For fully sunny locations, the seeding could be done later in July and still provide young zucchinis from late summer to mid-autumn.
Because the summer-sown plants bear mainly young leaves, they have always remained mildew-free in my garden. It’s the older leaves on zucchini and other squash plants that are prone to developing powdery mildew.
Dear Helen: I think my carrot and lettuce seeds must have fried in the heat. There is no sign of sprouting. When is it too late to reseed carrots? And how does one grow lettuce in the heat?
Depending on when you seeded the carrots, you may not have to give up on them yet. Carrots can take up to three weeks to germinate and perhaps a little more in conditions that are too cold or too hot. Temperatures above 27 C can reduce germination in carrots.
If you decide to wait it out a bit longer, keep the seeded bed lightly watered and try to provide some shading from the hottest sun.
Carrots can be seeded, in most conditions, up to July 1, for carrots to harvest in the fall, winter and early spring. I do an early spring sowing, and another, smaller one at the end of June or the beginning of July for younger carrots as a second crop.
Seeding lettuces indoors, or buying transplants, eliminates much of the uncertainty around growing satisfactory lettuce. Indoor sowing allows a gardener to have transplants ready as soon as soil and weather conditions are suitable for transplanting in the spring, and sturdy little transplants stand up to the heat of summer more easily than tender, emerging seedlings in the garden.
As the weather warms,
I look for lightly shaded areas where consistently adequate soil moisture is easy to maintain for placing lettuce transplants. I always use the shade of staking tomatoes and trellised peas for lettuces, for example.
Among the lettuces, butterheads are considered the most heat tolerant. Red-leaved lettuces tend to stand up well to heat as well. That’s probably why my row of butterheads and a miniature red romaine lettuce came through the period of high heat this month without any harm. That surprised me. I felt sure I’d find them fried into dust around mid-month, when temperatures soared.