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

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.

Floating row covers and vegetable insects

A previous post discussed germinating seeds with the fabric dual-marketed as seed germination fabric and floating row covers. The fabric covers placed over the top of plants can serve several useful functions including shading plants when transplanting, and shading to extend the life of cool season vegetables as hot weather approaches. They are also used to capture heat for fall frost protection.

Row covers are easy to use. Throw loosely over plants allowing slack for future plant growth. You can also use covers over hoops or wire tunnels such as in the photo above right. Anchor to the soil with U-pins bent from wire and punched through the fabric that touches the ground. Soil also can be mounded over fabric edges to hold it down. Covers allow light and water through and stop movement of insects.

Looking at what insects are trapped under covers with vegetable plants and which are barred access is worthwhile. Row covers can stop plant damage from troublesome insects such as spinach leafminer, aphids, leafhoppers, cabbageworm and cabbage looper. Summer pest protection is offered against squash bug, cucumber beetle, bean beetle, corn earworm, whitefly and grasshopper.

Before declaring victory and thinking covers will solve all vegetable insect problems, remember that several insects spend part of their lives in the garden soil. When they emerge to find their favorite plant food enclosed in a cover that protects them from predator insects, they readily multiply. Examples are cutworms and slugs that lurk in scattered soil locations.



Some insects concentrate on the soil immediately around their host plant and can be thwarted by crop rotation. These include onion and seedcorn maggot, flea beetle, Colorado potato beetle, corn rootworm (left photo larva in soil and right adult on corn silks) and tomato hornworm. Planting in the same location and using floating row covers can set up insect problems with these plants.

If a pest does multiply under a row cover, it may be best to remove it to allow natural enemies such as lacewings and ladybird beetles access to the pests. Also remember that squash and other vegetables depend on insect pollination so be sure not to screen out bees during flowering.

Photo credits:
* Row cover over growing tunnel, David Whiting
* Larva of the western corn rootworm, Frank Peairs, Colorado State University, Bugwood.org
* Western corn rootworm adult on corn silks, Tom Hlavaty, USDA Agricultural Research Service, Bugwood.org