Banner year for fruit set

It looks like a banner year for fruit set based on an informal look at fruit trees and conversations with Front Range fruit tree owners. Apricots and peaches may set fruit in an average of 2 years out of 5 and they both have fruit this year. Later blooming cherries (see photo left) and apples bloomed when temperatures were above 28 degrees also escaping freezes when in bloom.

The danger now appears to be too heavy a fruit set. Peaches tend to set fruit too heavily and should be hand-thinned when fruit reaches 1 inch in size. Space fruit 6 inches apart (see photo). Apricot fruit should be thinned the same way and thinning will produce larger-sized fruit just like peaches.

In a heavy-set year, we inevitably get July and August phone calls from people whose home peach tree limbs have broken from the heavy fruit load. Remember that peaches only bear on 1 year old wood and bearing branches will be removed at the end of the season, leaving this year’s branch growth to bloom and produce fruit in 2011.

Apples are not always thinned but could benefit from thinning in the case of heavy set (photo left). Natural “June drop” is typical in heavy fruit set years but may not always thin fruit enough. Thin in June to 6 to 8 inches or to every other spur. Break up clusters leaving only single fruit. DO NOT remove the long-lived spurs, only the fruit. Thinning fruit produces larger fruit.

Sour cherries also have spurs that produce for 2 to 5 years. Clusters are not generally thinned. Sweet cherry trees are less favored for the Front Range and not as hardy as sour cherries and other stone fruits. Branches can winter kill.

Photo credit: Cherry bloom, Peach fruit thinning, Heavy apple set - All Carl Wilson

Spring weather - hardening off transplants and bees

Two things have been frustrating about our spring weather. It’s been hard to put transplants outdoors to harden off. The days when temperatures have been over 55 degrees F or that winds haven’t blown have been few. Exposure to the outdoors helps leaves toughen and some plant movement thickens stems.

Note that there is a marked difference between the light intensity outdoors versus near a window indoors, as much as a hundred fold increase. The plants in the photo went from low indoor light to bright sun. They should have been placed in the shade outdoors as an in-between step. Even outdoor shade is considerably brighter than indoor light. The plants reacted to the bright light by turning white, indicating a breakdown of green chlorophyll (photo-oxidation). Gradually acclimating plants to brighter light is another reason to “harden-off” plants in stages lasting only an hour or two – if the weather allows.

Then there is the poor honey bee. They have gotten off to a rough start. Fall conditions were poor for them to set up stores for surviving the winter. Bloom was late this spring and though it is abundant now, the weather has usually been too cool for foraging. All and all this has been a stressful time for colonies and predictions are that many probably starved out.

In addition to weather, there is the worrisome problem of colony collapse disorder. Nationally, initial results from a survey by the USDA Agricultural Research Service and Apiary Inspectors of America show managed honey bee colony losses of 33.8 percent over the winter. Last year losses were 29 percent. These continued high losses are causing fears of poor crop pollination. Gardeners can do their part by planting bee-attractive flowers and avoiding the use of pesticides particularly during bloom periods when bees are active.

Photo credits: Solarization of tomato, Carl Wilson and Honey bee, Jack Dykinga

Spring 2010 review and outlook

Spring 2010 has been favorable for growing cool season vegetables seeded in late March or early April. Temperatures in April were near normal and not warm in Denver. Watering was necessary to overcome the many dry weeks of the month with the April 21 to 25 rain/snow upslope that left 2 inches of precipitation being the exception.

The first two weeks of May were cool (5 degrees below average) and dry (0.75 inches below normal) until the May 11-12 storm left over an inch of moisture. Fertilization and consistent watering of greens and developing vegetables were needed to maintain vigorous growth and quality.

The goal now should be to harvest spring crops as they reach best quality and mature them before the onset of hot temperatures. Whether higher temperatures arrive as early as late May or in June, bolting (seedstalk development) of spring greens and deterioration of quality will quickly follow. The semi-hardy vegetables can be planted in early to mid May including beets, carrots, parsley, parsnips, cauliflower and Swiss chard.

Plans should be made and seed and transplants purchased to follow spring crops with warm season vegetables. The first to go in are the tender vegetables including beans, corn, cucumbers, New Zealand spinach and summer squash. Transplants of cucumbers and summer squash should be delayed until the time for planting the very tender vegetables the end of May. Soil germination temperatures and daytime air temperatures should be consistently above 60 degrees F for this group. The soil temperature on May 10 was 53 degrees F (Ft. Collins data).

The very tender vegetables include melons, pumpkin, winter squash, eggplant, pepper, tomato and lima bean. This group is intolerant of frost as well as cool day and nighttime air temperatures below 55 degrees F. A daytime temperature of 60 degree F or higher is needed for growth. They should be planted when weather has become summer-like and the cool breezes of spring are past – at least two weeks after the last frost date (May 10 is average last frost date in Denver). They can be planted earlier with water walls or similar devices to provide nighttime heat and frost protection. Transplants are available at the Plant-A-Palooza plant sale May 15 .

Gardeners can make a difference

There is no more powerful combination than growing vegetables and generosity.

The Plant A Row for the Hungry effort urges gardeners to grow something for themselves and something to feed others. In Denver, the effort kicks off May 15 at the CSU Extension plant sale. Starter kits will be available for the first 100 people willing to plant vegetables to donate to Food Bank of the Rockies agency sites.

The plant sale is from 8 a.m. to 3 p.m. at the CSU Extension offices in Harvard Gulch Park, 888 E. Iliff Avenue. The sale features heirloom and modern tomatoes, hot and sweet peppers, other vegetables, basil, annuals and perennials. Plant flowers that attract bees alongside your squash, cucumbers, melons and other vegetables to make sure they are pollinated for good yields.

Starter kits include free vegetable and herb seeds donated by Botanical Interests, Plant A Row markers, Echter’s Garden Center coupons and other fun gardening items. You can double the pleasure you get from gardening by donating food to feed others in addition to eating food you grow yourself.

Transplant growing

Transplants being produced for setting out in mid to late May should be well along by now. The peppers in the photo are being grown for sale at our Plant-A-Palooza fundraiser. They are the improved chile types described in the recent “Back to the Future” article about chile seed that was cleaned up to be the more productive and flavorful peppers they used to be. Information on the sale is in the top right corner of the blog.

It’s been hard with recent cold/warm weather punctuated by rain/snow to move transplants outdoors during the day for a dose of sunshine. Even when day temperatures have been above 55 degrees F for peppers and tomatoes, it’s often been excessively windy. While mild wind is fine for promoting strong stems, gales are not.

Shuttle homegrown transplants outdoors on warm, calm days and bring them in before temperatures cool too much in late afternoon. This acclimates plants to drier air and UV light, helps build thicker stems with flexing from wind movement, and provides higher light intensity than generally available indoors. Leave plants indoors when air temperatures are in the low 50’s or below. Of course transplants of cabbage and other cool season crops will withstand cooler temperatures. Many of these should have been set out and already out of the house.

Do balance light and temperature to promote growth with adequate fertilization for good plant color. Avoid excessive fertilization which produces lanky, succulent growth. Watch for golden yellow lower leaves that indicates the need for nitrogen fertilizer and for purpling suggesting the need for phosphorous (photo left).

Between timing seed planting to have the plant the right size to set out, manipulating the environmental light and temperature conditions, and regulating fertilizer nutrients, growing transplants is an art as well as a science.

Photo credit: Chile pepper transplants, Phosphorous deficient tomato - both Carl Wilson

Winds don’t defeat seed germination efforts -

Wind, wind go away! If you regularly check this blog you might have gathered by now that I’m a big fan of germination fabric. With all the recent windy days, I thought the lettuce, kale, kohlrabi and other small seed I planted might not germinate. It seemed like the surface soil was drying out faster than I could replace it with once or twice a day watering.

Indeed I wasn’t sure the fabric would stay in Colorado and not end up in Kansas. This in spite of being secured with wire U pin anchors punched through the fabric into the soil plus heaps of soil piled on the edges. I got good germination, thank you, as you can see from the photos of lettuce seedlings left and the familiar notched leaves of cabbage family plants right. I know I couldn’t have achieved that germination percentage if it weren’t for the fabric.

Shallow planting to avoid burying seed and surface moisture for germination (wetting top ¼ to ½ inch) are critical to getting seedling emergence.

The next challenge is to keep seedlings moist enough to develop a root system and grow. After that they can be weaned from light, frequent watering to less time intensive every two day and then every three day watering. Gradual changes in watering frequency are best to avoid stressing plants. Keep them actively growing to preserve quality.

Photo credit: Lettuce seedlings and kohlrabi seedlings, both Carl Wilson