A bitter end to a sweet crop: why do plants ‘bolt’? by Jeff Pieper

What is bolting?

Bolting is when a plant’s growth suddenly goes from being leaf based, or vegetative growth, to being flower and seed based, or reproductive growth. A tell-tale sign that a vegetable has bolted is the elongation of the stem, or the formation of a central flower stalk in a very short period of time. Once you see this you know that the vegetative growth stage is over and that flowering, or reproductive growth stage, has begun.

Many of the plants that we find bolting here in Eagle County are plants that we are trying to grow out of their preferred growing conditions, think of trying to grow lettuce in the heat of the summer. Often times when plants switch to a reproductive growth stage it consequently leads to declining flavor, i.e., a bitter taste and a woody texture.

Why does bolting occur?

Bolting is a survival mechanism for a plant. The majority of the plants we grow in our gardens are annuals, and an annual plant’s life-cycle is to grow and produce seed in one season. That way the seed is mature and ready to over winter, germinate next season, and start the cycle all over again, perpetuating the species. For most of our cool season crops, we gardeners want the vegetative part of the plant’s life cycle to last as long as possible, but if our plants become stressed, the vegetative cycle halts and the reproductive cycle begins.  Stressors that trigger bolting include too much heat, too much cold, dry soil or overcrowding. These stressors may trigger a growth hormone, gibberellin, which signals to the plant that it is time for the last cycle; seed production. Mountain gardeners have even more of a challenge due to the short growing season and cooler spring temperatures; the stresses come not only from a sudden warm spell, but also from the cold weather the plant experienced early in the season. If plants are planted when the weather is too cool, this could signal the plant to bolt as soon as the weather warms up.

How to prevent bolting?

Bolting cannot be reversed, but there are ways to delay the process.

·         Provide rich soil that facilitates faster growth due to the abundant supply of nutrients.

·         Give plants a head start indoors under lights and place them outside while it is still cool.

• Sow frost resistant varieties before your last spring frost.
• Use mini hoop tunnels and other season extension tools to add a couple of weeks to your spring gardening. This provides a larger window to allow the spring greens to grow a good size before the heat of the summer.
• Practice succession sowing. Sow your vegetables every week or two instead of all at once, to increase your chances of germination and early harvest.
• Plant vegetables that are likely to bolt, in the shade, perhaps on the north side. Temperature fluctuations can be remedied by using a shade cloth to protect your plants on hotter days (75 degrees or more). 
• Grow a mix of cool season and bolt resistant varieties such as Orach (mountain spinach) or Malabar spinach (likes the heat).
• Thin seedlings promptly to eliminate overcrowding.
• Provide ample water throughout the growing season, especially when temperatures rise.

Lettuces can be kept from bolting by regularly picking the outer leaves, keeping them from maturing properly. This ‘cut and come again’ approach to harvesting can extend the time they produce for up to 10 weeks. Crops most likely to bolt are lettuce, radish, radicchio, spinach.  Biennial crops such as onion, beets, cabbage are less likely to bolt since we harvest them in the first year, and they bolt the second year, however, planting too early can cause bolting in biennial plants.

According to Colorado State University (CSU) Extension, cool season vegetables (leafy greens, root vegetables, and herbs) are easiest to grow and most productive for mountain gardeners. Look for varieties that have been bred to be resistant to bolting. Swiss chard and kale are naturally bolt resistant as are Correnta spinach and Spinner spinach. See CSU Extension web site for more information about growing vegetables in mountains gardens: http://www.ext.colostate.edu/pubs/garden/07248.html

Please email jeff.pieper@eaglecounty.us or call the CSU Extension office 970-328-8630 for more information about bolting or any other gardening questions.

A complex signaling system tells plants to stop producing leaves and to start producing flowers. This lettuce plant switched to a reproductive growth stage once temperatures got too hot.

 Onions are biennials so you most likely won’t see them flowering in your garden, however, if you leave them to over winter, or plant them too early, they will bolt the following season.

Introduction to Alpine Strawberries, Fragaria Vesca by Jan Boone, Master Gardener

As Spring started to show early signs of arrival, my attention was quickly taken in by a brief article on Alpine Strawberries in the Spring issue of Heirloom Magazine.  As a foothills resident, I thought it would be a great little experiment to try and educate myself on these for this season, so I’m sharing my experiences after 3 months of worthy efforts.  Here are 5 simple considerations to pass along from this trial:

1.       What exactly is an Alpine strawberry?  It’s not your standard hybrid Fragaria variety of garden plant with runners streaming down pots, across garden pathways and greatly loved by all for their fat red berries, sweet tastes and bountiful production. (Assuming no persistent birds or small critters are in close proximity).  The perennial Alpine origins are quite interesting, from Persia along the Silk Road into Europe and eventually into North America.  The Europeans started cultivation of the larger Fragariastrawberries in the 18^th century which eventually became the early forbearers of what the popular hybrid  varieties are today. The Alpine woodland favorites were originally known as Toot Farangi.  They are small fruited, equally sweet &  flavorful and even now a favorite decoration on French patisserie!  (No wonder I was taken).  Many varieties of Alpine strawberries have no runners and may be used as low, bush-like border or ground cover plants in the garden setting, with heights of 8-10”. Contemporary cultivars relish the sun, but there are several varieties that do well in partial shade.  It is easy to do an online search for cultivar characteristics of Alpines from larger growers.

2.       Challenge #1.  Sourcing.  Surprisingly, I found the larger urban garden centers mostly unaware about these Alpine plants.  Box store nursery sections are not the place to look for these small jewels.  Most garden centers directed me to seed packs, which were for the standard Fragaria plants!  A good friend suggested Boulder or Ft. Collins as better sources. Not being able to work day trips into my schedule, I resorted to the Internet.  I held my breath but ended up ordering 2 cultivars from a Delaware grower of Alpines.  The plants were reasonable in price.  So reasonable, I wasn’t sure what I’d get. I finally chose two runnerless cultivars , one for sun (Bowlenzauber) and another for part shade (Pineapple Crush).  Both rated well for growth and productivity. I was happily surprised when I opened the box to see the health & vigor of the plants.

Growing Alpines from seed is far more daunting and could be a true challenge for those patient enough to wait for the two year payout.

3.       Challenge #2.  Beds or Containers and what about soils at altitude??  Feeling inspired, I decided to split plants between beds and containers.  The beds were my standard foothills soil (sand & clay w/minimal organic matter). In one small bed, I added a one third mix of peat to loosen the soil plus nitrogen fertilizer to get roots established, then nothing was added  in the second Control area bed.   I caged both plantings immediately at the perimeter to discourage any sneaky little critters.  The balance of plants were assigned to small deck containers w/drainage holes.  The soils here were ¾ potting soil, ¼ peat and nitrogen fertilizer to establish roots.  (Official planting Day was April 14, 2016.)

4.       Challenge #3. Growing.  Water management is essential to keep plants and soils moist, as the plants become established. With luck I have found healthy leaf  growth and flowering as rewards!  I have had some sun scorch on leaves from part shade varieties, but as of late July, the amended soils bed area plants are alive with healthy leaves over the majority of the plant, but no sign of flowering. The non-amended Control bed plant seems to be shrinking in comparison!!  The container plants are quite happy with healthy leaves and several small flowers to date.  

5.       Challenge #4.  What next??  I have recently fertilized all plants to encourage bloom production.  I was only able to get a 20-20-20 fertilizer the day I went shopping, so time will tell.  I need to expand my knowledge in this arena. I have read that Alpines prefer a compost rich soil, so aged contributions from a friend’s horse were added in the past month.  Between now and October when the plant beds will be put to rest for the winter with mulch and compost, I will watch for insect and animal infestation. I may consider partial burial of the containers in a sunny southern exposure to over-winter?  I plan to also crisscross thread the tops of the cages to discourage browsing elk and deer attacks as fall gets closer.  To date, the containers have managed not to be discovered by the chipmunks.

This has been an enlightening trial.  Valuable lessons have been reinforced for me, yet again.  We live in an area where soils, fertilizing and water management DO matter. Barring any surprise hail or animal attacks, I hope to have at least several berries to adorn a tart soon.  I encourage everyone to take the time to experiment with something new in their gardens that can be shared with friends and family.

Colorado passes controversial legalization bill by Irene Shonle, CSU Extension in Gilpin County

Colorado passed a controversial legalization bill.  No, not THAT kind of legalization—we did that a couple of years ago.  No, this bill finally made it legal for us to do what every other state is allowed – or even encouraged—to do: collect rainwater off the roof! 

This is a game changer for Colorado, and especially for people who are on household-use only wells (who previously had NO outdoor water rights).  Rainwater is free and collecting rain could reduce storm water run-off issues.

The bill has not yet been signed by Governor Hickenlooper, but he is expected to do so shortly, as he has been a supporter.  Once signed into law, the bill will take effect August 10^th.

Here is the legalese of House Bill 16-1005:

PRECIPITATION FROM A ROOFTOP MAY BE COLLECTED IF: a)  NO MORE THAN TWO RAIN BARRELS WITH A COMBINED STORAGE CAPACITY OF ONE HUNDRED TEN GALLONS OR LESS ARE UTILIZED; (b)  PRECIPITATION IS COLLECTED FROM THE ROOFTOP OF A BUILDING THAT IS USED PRIMARILY AS A SINGLE-FAMILY RESIDENCE OR A MULTI-FAMILY RESIDENCE WITH FOUR OR FEWER UNITS (c)  THE COLLECTED PRECIPITATION IS USED FOR OUTDOOR PURPOSES INCLUDING IRRIGATION OF LAWNS AND GARDENS; AND d)  THE COLLECTED PRECIPITATION IS USED ON THE RESIDENTIALPROPERTY ON WHICH THE PRECIPITATION IS COLLECTED.

2)  A PERSON SHALL NOT USE PRECIPITATION COLLECTED UNDER THIS ARTICLE FOR DRINKING WATER OR INDOOR HOUSEHOLD PURPOSES.

3)  THE STATE ENGINEER MAY CURTAIL RAIN BARREL USAGE PURSUANT TO SECTION 37-92-502 (2) (a).

WSU Extension

I’m sure we will be seeing a plethora of rain barrels in our garden centers in August – or even sooner.  These have been conspicuously absent until now.

It is surprising how little rain it takes to fill those barrels – a half inch of rain collected from just a 200 sq. ft. section of roof will more than fill a rain barrel – and if your roof is bigger than that (most roof sections are), even less rain will do the job!

Some things to consider for your new rain barrel:

·         Place your barrel on a hard or compacted surface, near a garden area you intend to water.  Raise the barrel so you can get a watering can underneath the spigot at the bottom.    Because residents can collect up to 110 gallons, and most barrels are 55 gallons, you may want to look into connectors for the barrels, unless you will be collecting from two separate downspouts.

·         Make sure it has a lid to keep out critters, mosquitoes and children. Opaque barrels will reduce algae growth.

·         Use of rainwater on edible gardens can be tricky.   Everything from bird droppings to pollution to leachate from shingles can potentially cause problems.  These can be minimized by not collecting the first gallons of water after a dry spell (using a first-flush diverter), and only collecting off asphalt shingle or metal roofs (wood shake shingles can cause problems).  Only use food-grade quality rain barrels.  Look for future programming from CSU Extension on water quality issues with collecting rain water.