frost

February Tip: Spring cleaning in the garden

IMG_2761-1Unlike warmer winters, when many of the perennials in our gardens survived and even bloomed through the season, this year has been a cruel test of our gardens.

After repeated record cold spells, our gardens have suffered significantly more than recent years. The severe freeze damage we’re seeing has even the most seasoned gardeners wondering what will live and what will die when it’s all said and done. Is it dormant or is it gone for good?

We officially have only a few more weeks to worry about the danger of frost. But the excessive cold this winter could turn traditional garden wisdom on its ear. According to the USDA Hardiness Zone map for the Austin area, our average last frost occurs between March 1 and March 31. It’s typically the middle of March. But with this atypical winter, I’m trying to adjust my early spring expectations and prune a little more conservatively than I normally would on non-woody perennials.

But we can start pruning back our dormant woody perennials now—those tough native and adapted plants that now look like dead sticks in your garden.

Read the full article here.

By | February 28th, 2014|Tips|Comments Off on February Tip: Spring cleaning in the garden

Wait until last frost before you bring out the pruning tools

We left January with a 78-degree high one day and welcomed February with a 17-degree low the next. These dramatic swings in temperature are often painful for Austinites, for whom prolonged bitter cold is an anomaly. And it can wreak havoc on our gardens. Our plants don’t know if they are supposed to be dead, dormant or budding out.

As gardeners, we certainly want to take advantage of those sporadic and delightfully warm days to get caught up with our landscaping chores. But it’s still just a bit early.

There are still a few more weeks left with a danger of frost. According to the USDA Hardiness Zone map for the Austin area, our average last frost comes between March 1 and March 31. It’s typically the middle of March. (As we all know, using the term “typical” can get you into some gardening trouble here with our yo-yo like weather patterns.)

Try to be patient.  (I know it’s hard when the sun is shining and everything is dead, brown and ugly.)  Waiting to prune until after the last freeze prevents stimulation of new, tender growth that can be damaged by frost and can stress the plant by bringing it in and out of dormancy.

Getting started – pruners, loppers and shears

Good tools can make a big difference – for you and for your plants.  A clean cut is much better for plants than ragged or torn edges.  Sharp, high-quality tools like Felco or Fiskars brands make cutting easier for the gardener, too.  Use hand pruners for smaller plants and some woody perennials up to 1 inch in diameter.  For larger woody perennials and shrub limbs, longer-handled loppers help provide more leverage when cutting.  Shears work best for shaping smaller shrub branches or grasses.

Woody Perennials

First, assess the damage on your dormant perennials — plants like Lantana, Esperanza, or Salvia. If you scrape the stem of most of these perennials you will be able to tell whether it is alive and dormant, or whether it has succumbed to winter. Look for signs of green close to the base of the plant. Normal pruning of most of our perennials will suffice if the plant is just dormant. These woody perennials are typically very hardy. While it might take them a little longer to bud out after a cold winter like this, most do, unless they were newly-planted before winter or are particularly small and not well established. Make clean sharp cuts leaving about 6” of stem above ground. New growth from these plants will come from the base, so cutting them low will not affect their development.

Succulents

Many aloes and agaves were severely damaged by our hard freezes this winter.  Freeze-damaged succulents usually turn a lighter color, almost white, soon after the freeze. Later, the damaged part of the plant will wilt, and then turn black with rot. In some succulents, the affected parts eventually fall off.

If the center bud remains green and firm, the plant will likely to grow and recover, in spite of dead leaves. However, dead and damaged parts will never recover, and you can remove them. You should also look for new growth underneath the dead leaves and down in the base of the plant. These pups can often survive under the cover of the dead leaves.

Palm trees

If the center of the tree is fine, it will probably survive. Cut off dead or highly damaged leaves. Palms grow primarily in the warm spring and through the summer, and may look much better by the end of the summer.

Cycads – Sago Palms

Sago palms are popular in Austin, and many gardeners have them in their landscapes. Not actually palms at all, Sagos are cycads and they are normally hardy to 26 degrees. However, prolonged hard freezes cause damaged leaves to turn yellow or brown. These should be pruned to encourage new growth. You can remove all the leaves – they will grow back. If the trunk and leaf crown are still firm, the plant will likely recover.  Don’t worry if it looks like a bad haircut for a while – all the leaves will eventually regrow from the trunk.

Crape Mrytles

Some people start pruning Crape Myrtles earlier, but just like other plants, they are still susceptible to late season frosts and should not be pruned until after that danger has passed. In spite of industry-wide efforts to educate homeowners and maintenance crews about the dangers of “Crape murder,” you can still spot Crape Myrtles all over town that have been topped off — cutting back all the major limbs severely and straight across. It’s almost as though they’ve been put in a guillotine — and about as attractive.

It’s an odd practice, considering that no other trees like live oaks, elms, yaupon hollies or mountain laurels, are treated that way when they are pruned.

Crape Myrtles should never be topped. Removing the terminal growing section of a tree ruins the natural shape and appearance, stunts its growth and weakens it.  It can also reduce the number of blooms that the tree produces in the summer.  When pruned back too far, new branches may not be able to support the weight of summer’s blooms, particularly when wet. Crape Myrtles should be pruned for shape and style, removing any twigs or branches smaller than the diameter of a pencil.  To prune larger branches, trace down from the seedpod to where the stem meets a branch, and cut approximately 6 inches above that intersection.  This ensures that the new branch will be strong enough to support future growth below your cut.

Once you’ve finished pruning and everything starts to bud out, don’t be tempted to fertilize newly pruned plants. They need to use all of their energy to begin new growth.  Fertilizing now will over-stress them. Wait until later in the spring — at least a month — when they are established again.

By | February 19th, 2011|Articles|0 Comments

With cold weather on the way, prepare now to protect your plants

The recent dip in nighttime temperatures had many people (including me) scurrying around outside at night to protect their tender plants.

It is that time of year, when we play chicken with Mother Nature.  Will it really get that cold?  Am I in a little pocket that’s warmer/colder/somehow different than the forecast?  Some of us are in perpetual denial, while the rest (like me) run around like Henny Penny thinking the sky is falling.

Depending on the source you check, the average first frost in Austin is said to be anywhere between November 28 and December 5.  That means the time to prepare is now.

What’s the difference between a frost and a freeze?  Frost occurs when temperatures drop and moisture in the air condenses to dew and freezes on plants when it reaches 32F. (Plants lose heat faster than air, so it’s important to remember that plants can be damaged even if air temperatures don’t actually reach freezing.)

Frost may then turn into a freeze when temperatures fall below 32F. At that point, ice crystals may form inside plant cells, rupturing them.  When the temperature rises again, the cells leak, turning to mush and the resulting black foliage.

A “hard” freeze occurs when the temperature drops to 28F or below.  Long, hard freezes, such as those we experienced last winter, are almost impossible to protect against.

But, in an average Central Texas winter, there are many things you can do protect plants from frosts or freezes.

First, water moderately before the freeze.  Water loses its heat more slowly than air throughout the night.  Combined with covering plants or even a heat source, watering can help make a real difference by a few critical degrees.

Sheets, blankets and heavyweight row cover can all help protect plants from a freeze.  But it’s important to note that it’s not the cover that keeps the plant warm, it’s the radiant heat coming up from the ground that is held in by the cover.  Drape the cover all the way down to the ground and secure it like a tent with rocks, bricks or my favorite – canned vegetables (lighter than rocks, easier to find in a pinch, and they don’t mess up your sheets and blankets).

Do not, however, drape something over the top of the plant and then tie it around the trunk like a giant lollipop.  This is pointless, because you are actually keeping the heat away from the plant.  If you have plants that can’t withstand the weight of a blanket or sheet, you can plan ahead and use tomato cages, large boxes or PVC hoops or frames – really, anything to hold up the cover.

For particularly tender plants or a really cold night, you can also add a droplight or the large-bulb Christmas lights under the cover to create some additional heat.  Be careful not to let the bulb touch either plant or cover.

If temperatures rise above freezing – remove covers the next day to allow the plants to absorb the next day’s heat and recover as necessary.

Protecting container plants is a little trickier.  Their roots are much less insulated than plants in the ground and will get much colder.  To protect them, you can group them against your house and use the same techniques as you would for in-ground plants.  Even the littlest radiant heat from the house can help make a difference on a cold night.

But what do you do when we have a colder winter, or you have larger or more tender plants, that just need more protection.

If you have one, you can put them in a greenhouse.  There are many on the market – from traditional glass structures to mini houses made of plastic.  But beware, in the cold of winter, the temperature inside is usually the same as it is outside.  A greenhouse will require a heater to protect plants.  And, with our wildly fluctuating day and night-time temps, you will frequently have to open it all up and water daily when the days are nice and warm.  Even though the nighttime cold doesn’t change the inside temperature, the daytime sun most definitely does! My greenhouse can be 20 degrees hotter inside than the outside temperature on a really warm day – so be prepared to tend to the plants often and open and close the greenhouse daily.

Having spent years putting big pots of plants in the garage, this is also a great way to overwinter them, with a few conditions.  Remember, plants need light, and overhead light won’t cut it.  If you don’t have windows in your garage, make sure you open the garage door to let in sunlight and fresh air when temperatures allow.  In the garage, some plants will go dormant for the winter reserving their energy in their roots for the next spring.  Water them sparingly and let them rest for the winter. Once indoors, these plants require less water since there is no wind, and winter

daylight hours are shorter and lighting levels lower. More houseplants are lost to over watering than under watering. Water only when the top 1/2-inch of soil is dry to the touch. When their leaves drop, don’t worry and don’t fertilize them to try to push them into growth while they are inside.

How do you decide what to cover?  Different plants have varying cold hardiness – more established and mature plants have stronger, deeper root systems and can withstand more than tender plants or newly planted plants.  You may want to take extra care if you’ve put in a new fall bed or have recently planted new perennials.

Let’s say you weren’t watching the weather forecast and you lost some perennials.  What do you do now?  Don’t prune them.  I know it’s tempting to take that dead stuff off so you don’t have to look at it.  But, those freeze-damaged stems provide some protection for the plant for the rest of the winter.  And pruning encourages growth – the last thing you want now when there are several more freezes to come.  A repeat cycle of growing and freezing is hard on the plants.  Just consider them items of sculptural interest in your garden!

So, plan now – collect your sheets and blankets, find some tomato cages, lights and canned goods and you’ll be ready to go when a surprise weather forecast sets you scurrying at 5 p.m.

Frost tolerance of fall vegetables:

Possible damage by light frost:  Beans, cucumbers, eggplants, cantaloupe, Okra, peppers, pumpkins, summer squash, tomatoes

Can tolerate light frost:  Artichokes, beets, carrots, cauliflower, celery, Chinese cabbage, lettuce, peas, Swiss chard

Can tolerate hard frost:  Broccoli, Brussels sprouts, cabbage, collards, kale, kohlrabi, onions, parsley, peas, radishes, spinach, turnips.

And remember, frost can make leafy greens and root vegetables sweeter, so leave some of your chard and carrots in the ground until you are ready to eat them.

By | November 13th, 2010|Articles|0 Comments