Transplant growing

Transplants being produced for setting out in mid to late May should be well along by now. The peppers in the photo are being grown for sale at our Plant-A-Palooza fundraiser. They are the improved chile types described in the recent “Back to the Future” article about chile seed that was cleaned up to be the more productive and flavorful peppers they used to be. Information on the sale is in the top right corner of the blog.

It’s been hard with recent cold/warm weather punctuated by rain/snow to move transplants outdoors during the day for a dose of sunshine. Even when day temperatures have been above 55 degrees F for peppers and tomatoes, it’s often been excessively windy. While mild wind is fine for promoting strong stems, gales are not.

Shuttle homegrown transplants outdoors on warm, calm days and bring them in before temperatures cool too much in late afternoon. This acclimates plants to drier air and UV light, helps build thicker stems with flexing from wind movement, and provides higher light intensity than generally available indoors. Leave plants indoors when air temperatures are in the low 50’s or below. Of course transplants of cabbage and other cool season crops will withstand cooler temperatures. Many of these should have been set out and already out of the house.

Do balance light and temperature to promote growth with adequate fertilization for good plant color. Avoid excessive fertilization which produces lanky, succulent growth. Watch for golden yellow lower leaves that indicates the need for nitrogen fertilizer and for purpling suggesting the need for phosphorous (photo left).

Between timing seed planting to have the plant the right size to set out, manipulating the environmental light and temperature conditions, and regulating fertilizer nutrients, growing transplants is an art as well as a science.

Photo credit: Chile pepper transplants, Phosphorous deficient tomato - both Carl Wilson

Winds don’t defeat seed germination efforts -

Wind, wind go away! If you regularly check this blog you might have gathered by now that I’m a big fan of germination fabric. With all the recent windy days, I thought the lettuce, kale, kohlrabi and other small seed I planted might not germinate. It seemed like the surface soil was drying out faster than I could replace it with once or twice a day watering.

Indeed I wasn’t sure the fabric would stay in Colorado and not end up in Kansas. This in spite of being secured with wire U pin anchors punched through the fabric into the soil plus heaps of soil piled on the edges. I got good germination, thank you, as you can see from the photos of lettuce seedlings left and the familiar notched leaves of cabbage family plants right. I know I couldn’t have achieved that germination percentage if it weren’t for the fabric.

Shallow planting to avoid burying seed and surface moisture for germination (wetting top ¼ to ½ inch) are critical to getting seedling emergence.

The next challenge is to keep seedlings moist enough to develop a root system and grow. After that they can be weaned from light, frequent watering to less time intensive every two day and then every three day watering. Gradual changes in watering frequency are best to avoid stressing plants. Keep them actively growing to preserve quality.

Photo credit: Lettuce seedlings and kohlrabi seedlings, both Carl Wilson

Seed warm season crops indoors now

It’s now 7 weeks out from the May 31 traditional Memorial Day transplanting date for warm season crops into the garden. Even though the Denver last frost date is approximately May 10, many gardeners wait until the end of May when weather is more stable to set out tomatoes, peppers, eggplant, squash and more.

If you plan to grow your own transplants, 6 weeks before transplanting is generally sufficient for tomatoes and 8 weeks for peppers. Have the soil in pots warm (70 to 75 degrees F is ideal) and grow in a warm room, not cold basement. One advantage we have in Colorado is many days of bright sunshine so growing in a sunny window is doable even without a greenhouse.

A guide for seeding and transplanting vegetables into the garden based on outdoor soil temperatures follows (see last week for soil temperature details and on-line soil temperature readings link):

Garden soil temperature and planting times
35 degrees F – lettuce and onions
40 degrees F - peas, radish, spinach, cabbage
50 degrees F – tomato, pepper, corn
55 degrees F – beans
60 degrees F – cucumbers, squash, eggplant

Photo credit: Peppers seeded and growing in window - Carl Wilson

Time to seed early vegetables

A check of soil temperatures today showed 41 degrees F. That’s warm enough to seed cool season crops such as lettuce, onions, peas, radishes, spinach, cabbage, broccoli and kale in an open garden. (Those using coldframes could beat this planting date by a month or more.)

Soil temperatures should be measured at 4 inches deep at 8:00 a.m. If you don’t have a soil thermometer, you can follow the on-line readings taken at the weather station on the Fort Collins campus of Colorado State University.

Once seeded, you may want to cover with a germination blanket (photo above) to keep small seeds moist until seedlings emerge and even for a week or so afterwards. Our sun, wind and dry air at mile high elevation rapidly dry the surface of soil. This material, anchored with soil at the edges or U pins of bent wire punched through the fabric, helps the surface stay moist. It’s sold as floating row cover or seed germinating fabric at garden centers.

Even with a fabric cover and cool temperatures, at least daily watering likely will be necessary during the days to germination period generally listed on the seed package. In addition to proper planting depth (avoid seed burial deeper than recommended), maintaining consistent moisture is the biggest factor in successful seed germination.

Photo credit: Using seed germination blanket, Carl Wilson