Wednesday, July 16, 2014

It's Cherry time

Mature, rarely pruned cherry tree SW Denver
Yields of cherries look reasonable considering the 28 degree F lows we had on May 11 and 12. (See May 12 post on fruit bud damage). Damage at these temperatures was expected to be about 10 percent. Birds also are always a threat and can strip trees of fruit in a few days unless trees are netted.

Tart cherries are hardier than sweet cherries which often winter kill in addition to flower freezing. Sweet cherries are comparable to peaches in this respect.

Recommended tart cherries are 'Montmorency', 'Meteor' and 'Northstar'. If you want to experiment with sweet cherries, try 'Black Tartarian', 'Kansas Sweet' or 'Stella'. Tart cherries are self-fruitful while sweets need a pollinator.

'Montmorency' is the standard tart pie cherry variety that produces a July crop of bright red, firm textured fruit. It is planted in the new (second season this year) "Le Potager" food garden at Denver Botanic Gardens (see photo).

DBG 'Montmorency' cherry
'Meteor' is a very cold-hardy tree growing 12 to 15 feet tall. It develops heavy foliage that can minimize problems with birds. Fruit ripens mid to late July.

'North Star' is a dwarf tree topping out at 10 feet. It sets generally heavy crops of fruit that turn dark red for July harvest.

Note that bush cherries are very hardy and also possibilities. Nanking cherry produces some of the first flowers of spring, can grow to 6 feet and fruit is harvested in July if birds and squirrels don't find it first. Sand cherry is another bush cherry reaching 4 to 5 feet and produces mild-flavored, deep crimson fruit. Both are self-fruitful.

Photo credit: Both Carl Wilson

Thursday, July 3, 2014

Time for mid-summer planting

Vacant mid-summer "real estate"
Although warm season vegetables should be coming along well by now, don't forget about what you want to do with the vacant "real estate" in your garden from previous plantings.

April/May/June harvests of cool season and quick maturing vegetable crops often leave holes in the garden. While there is no problem with leaving ground fallow, do know that if planted before mid-July, a harvest can be gained yet this season. "60 dayers" (vegetables with 60 days to harvest or less) are what to think about planting now. Surprisingly, many cool season vegetables work well. Even though planted in the heat of summer, they will mature in cooler fall weather and be of good quality.

For more specifics on what to do to make a vegetable garden more productive from mid-summer through fall, consider attending my "Follow-on vegetable gardening" class at the Denver Botanic Gardens July 12 (click here for details).

Photo credit: Bare ground from harvest of spring crops - Carl Wilson

Monday, June 9, 2014

Growing vegetables in changeable weather

Tomato growing out of Wall O'Water. These
tomatoes are the same ones that were protected
from the hail discussed in the previous post.
By June 9 you might expect the weather to be consistently warm to support the growth of warm season vegetables. At Denver's mile high elevation it isn't so. Low temperatures last night reached 43 degrees F and tonight's low is predicted to be 49 degrees.

Plants such as tomatoes and peppers are set back by lows under 50 to 55 degrees F and take days to resume growth. Development and harvest of your tomato or pepper crop is delayed from the labeled days to harvest number for the variety. That number is based on favorable growing conditions.

Tomatoes growing in Wall O'Waters with a source of heat (warm water in side channels) fare better. Even though the tops may have grown out of the water walls the heat is enough to moderate a cold night and keep the plant actively growing for a close to on-time harvest.

Climate modification through devices such as Wall O'Waters is important for vegetable gardeners to practice in our changeable Front Range Colorado climate.

Squash seedlings growing in a hill.
On another subject I was recently asked why it is recommended that squash and other vine crops be planted as a group in hills. The answer is soil drainage. In addition to last nights cold, my rain gauge measured 0.8 inch of rainfall yesterday. That's enough to saturate and water-log soil without good drainage. This can lead to stunted growth and root rots particularly in our compact clay soils. Although gardeners may get tired of hearing people recommend the virtues of soil improvement for growing vegetables, it is good advice.

Photo credit: Tomato growing out of Wall O'Water, Squash planted in a hill - both Carl Wilson

Tuesday, May 20, 2014

Another reason for water walls and row covers

The water tubes keep tomatoes warm through
 the sudden drop in temperature
It's been challenging gardening in Denver, Colorado this May. Early in the month it was 85 degrees F on May 4. Then we had snow and a 28 degree F low on May 11. Back to a 84 degree F high on May 18. Today, May 20, it was a hailstorm (see photos).

Kale and mesclun are cool season vegetables
 but this is too much. Brrr!
Thank goodness for growing in Wall O' Waters that provide the tomato transplants some hail protection. I expect plants to bounce back quickly, much faster than tomatoes growing in the open that are now sticks.

The greens under row cover fabric had a little protection and will regrow after their "trimming". It is definitely time to replace the fabric though.

Some gardeners go to the trouble to erect a frame with shade cloth fabric as a hail screen. In our variable climate, it can be a good idea.

Photo credit: Tomato in Wall O' Water after hail, Kale and Mesclun mix under row cover fabric post hail - both Carl Wilson

Monday, May 12, 2014

Fruit bud damage after the storm

May 12, 2014 snow on cherry fruit buds
Cold damage to plants is often much greater the day following a storm. This is when skies clear and without a cloud blanket to hold heat in, radiational cooling comes into play. At high Front Range Colorado elevations with low humidity, plant cold damage from this type of cooling is common.

At this stage of tree fruit bud development (full bloom to petal fall), we can expect 10 percent bud kill at 28 degrees F and 90 percent bud kill at 25 degrees F. This is with a 30 minute exposure and it doesn't matter if it is apples, cherries or peaches. European plums are somewhat hardier and it will have to go down to 23 degrees F to reach an expected 90 percent fruit bud kill and similarly to 24 degrees F for pears.

Cold damage to developing buds of fruit trees can be minimized by planting near the tops of slopes where cold air drains to lower levels and by avoiding blockages (such as fences) to cold air draining away .

Good yields of tree fruit may only be achieved in 2 or 3 years out of five on Colorado's Front Range. This is looking like it could be one of those off years.

Photo credit: Cherry fruit buds in May 12, 2014 snow - Carl Wilson

Friday, May 9, 2014

Greens weather returns

Winds and unseasonably warm Front Range Colorado weather (85 degrees F on May 4) may have been discouraging to those growing spring greens. If you had them protected and growing under a row cover fabric "dome", you gained several advantages. They were encased in a slightly higher humidity environment, shielded from the worst of the winds and recent heavy raindrops (and in some places hail), and protected from rabbits and other marauders.

Now that we're back to cooler weather (more seasonable 60 to 70 degrees F highs), early planted greens are maturing rapidly. It's time for cut and come again harvesting. Shear 2 inches above the soil line so they will regrow providing another harvest.

Another benefit to growing greens under row covers is that soil doesn't tend to be splashed up on the leaves because rain and irrigation droplets are cushioned and filtered through the spunbonded fabric. Less soil on leaves makes washing them a snap. The tempered row cover environment also enhances quality - so tender!

Meanwhile this upcoming Mother's Day weekend highs in the mid 40's F and lows around freezing with predictions for a rain/snow mix augur poorly for those who have already planted warm season vegetables. If you have tomatoes and peppers snug in water walls, no problem. Cool season vegetables will of course be right at home in this upcoming cold/snowy weather.

Photo credit: Mesclun filling row cover, Cut and come again harvesting of mesclun greens - both Carl Wilson