the Sacramento Valley!
Written for the Davis Enterprise, June 29, 2001
Isn't it getting too late to plant?
Is it too hot to plant now?
Shouldn't we wait until fall?
What is the "best" time to plant?
Contrary to popular belief, the periods of extreme summer temperatures shouldn't cause you to stop planting. Most plants establish and grow best in a temperature range of 55 - 90F, and most of our summer here is in that range. Even in a very hot summer (1998) more than half of our summer days were below 90 degrees--ideal temperatures for rapid root establishment and growth of new plants.
Our typical summer pattern is short heat waves interspersed with moderate, breezy weather. A few days over 100 are usually followed by a few days in the 80's as the delta breeze pushes cool marine air over our side of the valley. Hottest weather usually comes in July to August, but we can have temperatures suitable for planting at any time during the summer--just as we can have heat waves anytime from early May to mid October. The key is proper followup care, and keeping a close eye on the weather.
Our growing season for plants that need heat lasts into mid-October. Tomatoes, peppers, and eggplants will produce fruit within 60 - 80 days of planting, so we can plant them into late June. Avid vegetable gardeners plant sweet corn and bush beans into early July; Kentucky Wonder beans, which prefer cooler weather, can be planted in August for a fall crop. Pumpkins for Hallowe'en Jack-O-Lanterns should be planted on July 1. Make space in your garden for the winter vegetables that require an extra long growing season: Brussels sprouts and rutabagas should be planted in July for harvest next winter (you wouldn't want to be without Brussels sprouts or rutabagas, would you?).
Some heat loving annuals shouldn't even be planted until May, and can be planted well into August for showy blooms into late October. The real heat lovers include China asters, Cosmos, Portulaca, Verbena, Vinca rosea (Catharanthus rosea), and Zinnias. All of these prefer to be planted in hot, blazing sun. These flowers come in strong, almost electric colors, suitable for dramatic borders or spots of color in containers.
Vinca rosea (Catharanthus rosea) loves to be planted in hot, blazing sun!
Is it too hot to plant or garden?
Not necessarily. The only time we stop planting here is when the soil is too muddy due to winter rains! Any time you can work the soil, you can plant. If highs are in the upper 90's to over 100, hold off for a couple of days. Don't spray pesticides or apply fertilizer when it's above 90F, as you risk burning the foliage. Fertilizer applied during the summer should always be watered in immediately. If you're going on vacation and can't have someone check new transplants daily, wait to plant until you return.
Your own comfort can be a guide to planting. If you're uncomfortable out there, then it's probably not a great time to plant. But on a warm day you might be comfortable in the morning, even up until about noon, or in the early evening when our delta breeze comes in.
And remember to keep cool, drink plenty of water, and avoid sunburn!
The key to planting in the summer is proper watering.
Water each plant as it is planted, then water the whole area thoroughly by hand, or run the water system. Check each plant the next day for watering and water by hand if necessary. After that, new transplants should be checked daily but will probably need water only every 2 - 3 days. You can't rely on an automatic watering system to take care of newly planted plants, because it can't adjust for the fluctuations in our summer temperatures and the water requirements of individual plants. Wind, especially a gusty north wind, will dry young plants very quickly.
The smaller the pot you transplanted from, the more often it will need watering for the first couple of weeks. Most new plants in shade will only need water 2 - 3 times per week, while new plants in sun may need water every other day; daily if our weather is unusually hot or windy. New transplants will droop even if they are watered, especially if they have broad leaves, due to transplant shock. Don't overwater them just because they wilt slightly during a hot afternoon.
Shouldn't we wait until fall?
Some plants actually prefer being planted in the summer. All through the spring customers ask for subtropicals: Bougainvillea, Lantana, Passiflora, and others. Citrus wholesalers scramble to have material ready for the busy spring season, but all of these plants root and grow more quickly in warmer soils
Some nursery stock isn't available until summer, and you might miss the season.
Shade trees and deciduous fruit trees that you didn't buy during the winter bareroot season aren't usually available in the spring, as the growers need to get them fully rooted into containers before they'll ship them. These plants are usually available after early June and into the summer. You could wait until next winter, but then you lose a whole summer of growth.
Many trees, especially Crepe myrtle(Lagerstroemia hybrids) and Rose-of-Sharon (Hibiscus syriacus) are popular for their showy summer blooms, so wholesalers grow their crops for sale when they're flowering. They are rarely available in reasonable quantities until early summer, and most nurseries are sold out by fall. If you wait until fall to plant, you'll only get the leftovers. Many perennials (lavender is a good example) also need some heat to develop size in containers, so availability is often limited until summer.
What is the "best" time to plant?
This suggests a narrow window for planting-- a few weeks in the spring, after it's not "too cold" and before it's "too hot," and a few weeks in the fall before the rains begin, when planting is optimal. This might be true in more severe climates such as the midwest or northeast, where severe winter cold and muggy, buggy summers limit gardening and other outdoor activities. In California we can garden nearly year-around.
There are some plants that are trickier to establish during summer weather, including native plants and new lawns planted from seed. Natives need very careful watering as the roots grow out of the nursery container soil, but are vulnerable to crown-attacking fungus in warm weather. Since those fungus aren't active in cool weather, fall is a better time for planting natives. New lawns from seed require water as often as 3 - 4 times daily to germinate in hot weather, and are vulnerable to seedling diseases. New lawns can be planted from sod anytime the soil is workable: spring, summer, and fall.
Watch the weather forecasts!
When the breeze is coming in from the southwest (12 mph or more at 6pm in Fairfield is a good rule of thumb) we're on the way to great planting weather over the next few days in the Sacramento Valley!
© 2008 Don Shor, Redwood Barn Nursery, Inc., 1607 Fifth Street, Davis, Ca 95616
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