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

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

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

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

Week to cover-up

Mesclun growing under row cover fabric

A week of 30 mph winds on Colorado's Front Range with both daytime and nighttime temperatures below seasonal averages presents a great opportunity to talk about plant protection and season extension "cover-ups".

Using floating row cover fabric to grow early spring crops made even more sense this week. With soil covering the edges, this lightweight, spunbonded polyester or polypropylene fabric stays in place even though it flaps in the wind. Indeed it should be loose for plants to grow. The fabric provides just enough tempering to moderate wind and cold temperatures while water and light penetrate for plant growth.

If you haven't tried growing under row covers, do so to realize the benefits including wind protection; earlier and increased harvest; pest protection from insects, rabbits and squirrels; frost protection; water conservation and more (see here). Many local market growers are making extensive use of fabric covers for field production. They work equally well in home gardens. Just be sure to peek under the cover once in a while. Weeds find the tempered environment equally conducive for growth and you don't want to miss peak harvest quality because crops are "out of sight, out of mind".

Wall O' Waters set up to warm soil

Another forward looking cover-up this week is preparation for early planting of warm season vegetables. Use of Wall O' Waters to warm soil for future planting of tomatoes and other warm season crops made sense after last weeks warm weather and before this weeks cool-down. Made in Dillon, Montana, this product has a proven record of enabling home gardeners to plant earlier and protect tomatoes from winds and frost. The water-filled channels in the sides are heated by the sun to warm the soil and then protect the plant inside. The manufacturer recommends setting them up at least a week prior to planting to allow for warming the soil for roots.

Wall O' Waters used with black plastic mulch

Wall O' Waters can be used either alone or in combination with another cover-up, black plastic mulch. Even though clear plastic works better for warming soil, black plastic does a fair job and can be used around water walls to prep a garden soil even more for an early May planting of warm season crops. Yes, our average last frost in Denver is May 5 but cold weather often extends later in the month. Plant protection and season extension make sense in our climate.

Photo credit: Mesclun growing under fabric row cover, Wall O' Waters set up to warm soil, Wall O' Waters used in combination with black plastic mulch - All credit Carl Wilson.

Spring sowing of greens

Germination using straw mulch

Time remains to sow spring salad and greens crops in our March to April spring planting period. The nice thing with these crops is that they can be cut at any stage of growth with cut-and-come again harvesting. This means no waste from late sowings that can be harvested before they fade in June heat.

The seedlings in the photo were germinated under a layer of straw mulch. Straw is a useful organic mulch to use in spring before lawns green up and grass clippings become available.

Want to add some pizzazz to your salads? Red orach also called mountain spinach is worth trying. It's native to Europe and the Balkans. Adding red leaves with their mild spinach-like flavor to an otherwise green salad provides a nice complementary color contrast. Orach can be used for presentation purposes as a bed of red on a serving plate. It also can be cooked as a green in soups but red varieties lose their color.

Red Orach  Atriplex x hortensis

Several varieties are available from the magenta shown to purple and various shades of green. Red orach seed is widely available and easy to grow once soil temperatures reach 50 degrees F. Do not sow where spinach, beet or chard have been or will be grown in crop rotation

The best leaves to pick for salads come from the first 18 inches of plant growth made in 40 to 50 days. Orach is both alkaline soil and drought tolerant. It is slower to bolt than spinach but will bolt in summer.

Orach is an annual growing to 4 feet or taller and will self-sow readily if left to mature so be warned and harvest it young if you don't want it coming up all over your garden in future years. Seedlings from saved or naturally spread seed tend to have a lot of color variation.

Photo credit: Straw mulch for seed germination, Red Orach growing with drip irrigation - Both credit Carl Wilson