Hail NO!! - But for some unfortunately YES

June is always an unsettled weather month in between cool May and hot July. Hail has already been a worry for growers and some have already taken their licks. A June 8 storm nailed Ft. Collins and a short pelting got a vegetable project I'm working on in Denver on June 13.

Vegetables with broad leaves take it hard as evidenced by the broccoli photo right. Soil may also crust afterwards as seen in this photo from a clay soil northeast of Ft. Collins. With the heavy rains that frequently accompany hail, it is often best to stay off the soil until it dries out to avoid further compaction. There is little you can do at that point anyway. Once soil dries, cultivation to break up crusts may be helpful.

Hoops for low tunnels with floating row cover fabric at the ready may offer some protection if you're on the spot to pull up covers when hail threatens. If hail stones are large, fabric may be shredded and protection value likely decreases.

Patience is a virtue after a hail storm. Once it is time to water again, consider weak fertilizer in the water to add to the stimulus for new growth delivered by the hail pruning. If plants aren't responding after a few weeks, remember the possibility of early July seeding of the 50 to 60 day vegetables for fall harvest.

Vegetable plants are resilient following hail and growers can only imitate that quality.

Photo credit: Hail damage on broccoli, Soil crusting following hail, Low tunnels and row cover fabric - All Carl Wilson

To Mulch or Not

Vegetables are sensitive to environmental changes and the recent mix of hot and cold weather has had effects not just on transplanting warm season vegetables as mentioned last post. Some early season crops have already started to produce flower stalks. Remove and use the space to seed or transplant other vegetables maximizing production. Selecting a succession vegetable from a different plant family is good crop rotation practice.

If lettuce bolts for example, planting a rotational root vegetable such as carrot contributes to soil health as would adding compost before seeding. While carrots are easier to seed when weather is cooler, seeding is possible even in hot weather.

Carrots require 14 to 21 days to germinate. The chances of the seedbed drying out in this time are greater than with 7 days to germination seed. There is simply more time for something to go wrong whether it's windy weather or an irrigation problem that leaves soil dry.

Mulching with floating row cover fabric is one good solution for most seeded crops. To further increase chances of success with a many days-to-germination crop such as carrots, try doubling the mulch cover. Place grass clippings on top the fabric. Water easily percolates through both to wet the soil.

Periodically check under the fabric for signs of germination particularly once the 14 day mark approaches. Clippings are easily gathered when lifting the fabric and can be used elsewhere in the garden or in compost. Clippings alone generally are not used with carrots because they entangle with the ferny foliage.

As for mulching elsewhere in the garden in early June, definately avoid mulching peppers. It may be tempting to apply mulch during tranplant establishment but mulch delays soil warming. Wait until early to mid July to mulch peppers so soil thoroughly heats. This can make the difference between a good versus a poor or no harvest of peppers.

As for other warm season crops, it may be early to mulch them too. Efforts are probably better placed on proper watering and fertility to get plants established and hasten growth so they can outgrow flea beetle invasion that is common this time of year. More information on control of this insect can be found in the CSU Extension fact sheet, Flea Beetles.

Photo credit: Lettuce flowering, Seeding carrots, Double mulching with grass clippings over fabric - all Carl Wilson.

Pull the trigger on warm season transplants

It looks like this will be the week that temperatures finally warm up for good along the Front Range making it safe to plant the warm-night loving vegetables. If you've been able to walk the tightrope between maintaining transplant condition while keeping them indoors at night and outdoors to harden on decent days, versus planting in the garden because they are too big, congratulations.

For those who have managed transplants to hold for planting this week, the warm nights above 50 degrees F should promote rapid establishment and growth. If you had to transplant last week or earlier, your plants may sit stunted for a while until they recover. Unfortunately this adds days to harvest to your tomatoes, peppers and other warm season plants.

While frost danger appears to have passed in Denver on May 2nd (31 degrees F), the night temperature was 33 degrees F on May 16. Although mostly in the forties and a few high thirties since then, it was still cold to think about setting out squash, peppers, tomatoes, eggplant and others.

Fertilizing transplants to keep them in good condition was helpful as long as this didn't cause too much new growth. A fully soluble vegetable fertilizer that contained phosphorous as well as nitrogen helped avoid purple backs to leaves, a sign of phosphorous deficiency.


Some plants that ran out of fertilizer could be turned around by fertilizing as these tomato transplants have been.

Photo credit: Fertilizing transplants, Phosphorous deficiency on tomatoes, Tomatoes turned around with soluble fertilizer - All Carl Wilson

Holding transplants

• With forty degree nights, growers are in a balancing act between how long transplants of very tender vegetables can be held versus planting and knowing they will be set back by the cold.
  
  Many transplants may be running out of nitrogen as seen on the tomatoes in the top of this photo. These plants are starting to come back with addition of a soluble nitrogen fertilizer when watering. A product that also contains phosphorous is useful to avoid the purple backs of leaves seen with phosphorous deficiency. The tray of plants at the bottom of the photo received regular fertilization.
  
  Don't apply too much fertilizer or you will end up with lanky growth. Of course these plants could be bumped up to pots larger than the 4 inch ones they are in but that is hardly desireable considering planting can hopefully be done in a week or so once nights are at least above 50, preferably 55 degrees F.
  
  What can be done in the meantime while waiting for warmer nights?


• Harden off plants by moving them outdoors on suitably warm days and back in at night.
  


• If tramsplants are very tender cover them with floating row cover fabric while outside. This should prevent sunscalding until they've adjusted to higher light intensity and have hardened off.
  


• Maintain enough fertility to keep transplants growing and leaves from turning yellow.
  


• Remeber that transplants set out too early or transplants running out of fertilizer require recovery time which adds to the days to harvest time.



• Keep blossoms pinched from plants. Now is not the time to set fruit as you want to keep them in vegetative growth, not flowering/fruiting growth.



• Watch the weather forecasts for when night temperatures are predicted to be 50 degrees F or higher.



• Transplant tender (not the very tender) transplants such as cucumber and summer squash that tolerate cool nights as long they are above freezing. Remaining cool season vegetable transplants such as chard, beets, romaine lettuce that will hold up better in summer heat, cauliflower, etc. can be put out (photo).



• Finish any soil prep such as compost additions and build new beds while weather is cool to work.

Photo credit: Held tomato transplants, Planting cabbage, romaine lettuce, Swiss chard - Both Carl Wilson

Anxious to Plant

Like everyone else, we are wondering when temperatures are going to thoroughly warm in order to transplant warm season vegetables to the garden. The five day forecast consistently shows "lows in the lower to mid 40's." For tomatoes and peppers, nighttime lows should be no lower than 55 degrees F.

The problem everyone is having is tomatoes stuck in the greenhouse getting leggy. Getting them out of a humid greenhouse where they can be put out on warm days and brought indoors into a non-greenhouse (drier) environment for night protection is ideal for hardening off. This should slow growth and curb leggy tendencies.

The outdoor part of this daily plant shuttle should have them located in a protected, short sun exposure location. Plants exposed to intense Colorado sun often sunscald because they have not developed the chlorophyll-protective plant pigments to shield them from UV and intense light.

One tomato plant brought to me this week for diagnosis showed the typical bleached, thin tan tissue typical of high light exposure. Transplants grown indoors during the cloudy spring weather we've had don't have the ability to stand up to the occasional clear day of intense Colorado sunlight.

Meanwhile, cool season vegetables such as this pak choy are happy growing in the cool, moist weather. The warm season transplants are just going to have to wait until Memorial Day weekend or later for the warm nights they require.

Photo credit: Greenhouse tomatoes and Pak Choy - Carl Wilson

Unique tomatoes and chiles featured at plant sale

Vegetable gardeners looking for better plants can find them at the CSU Extension Plant-A-Palooza plant sale May 14. The sale features tomato plants from around the world and better chiles for chile lovers.

Tomatoes available include Azoychka, a Russian heirloom that produces yellow, 3-inch tomatoes in 70 days. It has a good acid content to balance its sweet, citrusy flavor. Zhefan Short is from the Zhengjiang province of China. This 68 day tomato produces pink 3 inch fruits with good sweet/acid balance in the juice. Stupice from Czechoslovakia is a prolific, early bearing red type with great taste. Other heirlooms will be available too.

The chiles featured are grown from seed acquired from the New Mexico Chile Pepper Institute. The Institute returned fifty year old seed lines to what they used to be before they wandered off-type in the last few decades. The bonus for gardeners is traditional heritage chiles that yield 10 percent more and have 20 percent more flavor.

Two chile types will be sold. ‘Nu-Mex Heritage 6-4’ provides consistent medium heat with good yield. ‘New Mex Big Jim’ produces a high heat level for those who like their chiles hot.

The Plant-A-Palooza plant sale fundraiser has long been known for heritage tomato transplants in addition to modern tomatoes, peppers, basil, perennials and annuals. The sale takes place on Saturday, May 14 from 8 am to 3 pm or sold out in Denver’s Harvard Gulch Park, 888 E. Iliff Avenue (at Emerson Street). More information at 720-913-5270.

Photo credit: Tomato transplants, Carl Wilson