Still Useful to Plant in Wall O' Waters

Denver is receiving more sun and temperatures have warmed this week. That doesn't mean that it is ideal weather for planting tomatoes and other warm season vegetable transplants. Nighttime temperatures are still falling into the forties, far below the 50 F (and better yet 55 F) degrees nighttime temperature requirement for tomatoes. Note that the vine crops (squash, melons, pumpkins, etc. require 60 F degree nights).

A week after water channels filled at 
setup of Wall O' Water, sun has warmed water
sufficiently for planting within WOW cone. 
Plant deep for rooting along stem of this leggy 
tomato transplant.

So what's a gardener to do? You may have raised tomatoes from seed on your windowsill or purchased at a plant sale and the transplants are getting leggy. This is where Wall O' Waters come to the rescue. Even though often thought of for use in planting in the garden in April, they are still useful now.

Unlike mid-May when cloudy skies provided little solar radiation for heating the water in the tube walls of the Wall O' Waters, we are now receiving more sunlight. This provides warmth at night offsetting still cold night temperatures. Planting in Wall O' Waters also provides protection from wind and a sheltered environment for recovery from transplant shock.

Another benefit is protection from hail until plants grow above the walls. Even then plants pruned to the top of the Wall O' Waters by hail will retain enough undamaged plant within the Wall O' Waters to regrow.

If warm season transplants are planted in the open now without protection, they recover from transplant shock slowly and become stunted. We are assuming that night temperatures remain above freezing. They will require a week or more to recover from cold night stunting even when night temperatures warm above 50 to 55 degrees F in June. Although plants are leggy, you may be better off keeping them in pots and bringing them indoors at night until night temperatures warm if you aren't using Wall O' Waters.

See the manufacturer's website for more information on Wall O' Waters. Look to purchase them at your favorite local garden center.

Photo credit: Leggy tomato transplant for planting in Wall O' Water - Carl Wilson

Warm Season Vegetable Transplanting and Plant Sale Recommendation

This past week we saw a week of rain ending with snow that dropped 3.3 inches of precipitation in my Denver garden. The wet week ended May 10th with an overnight low of 31 degrees F.

Two years in a row! Tomatoes in Wall
O'Waters on May 12, 2014.

Any early-transplanted warm season vegetables required protection with Walls O'Water or second best the use of frost blankets. Even so warm season vegetables will likely be set back and take time to resume growth. Cloudy weather during the week didn't allow much solar gain for Walls O'Water.

Planting thoughts this week should take into account wet soils. Give them time to dry to a medium moisture content before transplanting or seeding. Don't walk in or work soil when wet; you will only destroy soil structure if you do. Meanwhile, consider what warm season vegetable varieties you want to plant this year.

Vegetable transplants being grown
by Denver Master Gardeners for their
May 16 and 17, 2015 sale.

I'm impressed with the wide selection of vegetable varieties offered by CSU Extension Denver Master Gardeners at their spring plant sale this coming weekend. The sale is Saturday, May 16 from 8am to 3pm and Sunday the 17th from 10am to 3pm.

Location is the Denver CSU Extension office in Harvard Gulch Park, 888 E. Iliff Ave, Denver, CO. This plant sale promises to be worth a visit and proceeds benefit CSU Denver's education programs.

Click to download and then open this file for more information and a list of varieties offered at the sale: Denver CMG Spring Plant Sale.

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

Warm season finally arrives

Whew! It was great to finally get the transplants off the porch and into the garden on Memorial Day weekend. Even then nighttime temperatures were only high forties – still a little cold for tomatoes and peppers.

The first half of May was very cool in Denver. Although it didn’t freeze past the average last frost date of May 10, the nights were cold. People wanting to transplant early had to provide season extenders such as water walls for nighttime heat.

Those transplanting without season extenders once again proved the wisdom of waiting two to three weeks past the average last frost date. Only by then had the weather settled and cold winds turned warm. I had questions about why peppers and tomatoes weren’t growing from people transplanting early in the month. The answer is cold nighttime temperatures under 50 degrees F.

Now it looks like daytime temperatures will reach close to 90 degrees F with nighttimes in the low 50’s – perfect for warm season vegetables. This is typical of our high and dry steppe climate, going from cold to hot in a short period of time.

Continue to seed those 60 day root crops. Even though beet seed is larger than carrots (photo), I use germination fabric over both to keep the seedbed moist and increase germination percentage. It’s a great tool particularly on 90 degree F days when soil dries out so fast.

Photo credit: Protecting transplants, Transplants in garden, Beet seed - all Carl Wilson

Thinning vegetable seedlings

Thinning overcrowded seedlings is essential following germination. Seedling competition will set back your crop and delay harvest. Some people prefer to thin partially as a hedge against possible later seedling losses. Whether you thin partially or completely to final spacing, do thin. The following photo log provides tips and tells you how. Note that these photos picture thinning for a wide bed or Block style layout, not a row. Wide bed planting results in a greater harvest for your efforts.