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Gardening Tips With Nan Sterman

August 14, 2012

Nan Sterman

Nan will take all your gardening questions today immediately following her appearance on Midday Edition, beginning at 1pm. Submit your question below from 1-2pm, Tuesday August 14th.

This chat has already taken place. Read the transcript below. Note: The transcript is in reverse chronological order.

Pizzaguy - you are most welcome!

And everyone else, thank you for your great questions. I look forward to the next time I get to chat with you.

In the meantime, if you need more information, pick up a copy of my books, California Gardener's Guide VII and Waterwise Plants for the Southwest.

There's more information on my website, www.plantsoup.com

Have a great day and stay cool!

Nan Sterman | at 2:03 p.m.

Thanks for all the advice!

Pizzaguy | at 2:01 p.m.

Pizzaguy if the roots can't penetrate, that sounds like it may be hardpan. Do talk to a professional before determining whether it is truly hardpan and the best methods for breaking it up - BEFORE you finalize things with the bobcat operator. ; }

Nan Sterman | at 2:01 p.m.

Thanks Nan.

esteban | at 1:59 p.m.

follow-up:

Not roots in the hard clay (that fits your description)...

Pizzaguy | at 1:59 p.m.

Pizzaguy - is it hard clay or is it hard pan? Hardpan is an almost solid layer that prevents water from draining past it and roots don't generally penetrate it. Hardpan needs to be broken up mechanically (i.e. by heavy machinery). I'd have to see it to know what you have. You might ask your contractor.

Nan Sterman | at 1:57 p.m.

Thanks for the suggestion on lawn vs. fruit tree irrigation. That helps a lot!

Also heres a follow-up to the "hardpan" clay question:

From what I can see, there are:
5- inches of topsoil
4 - inches of sandy clay
and several feet of hard packed clay

Pizzaguy | at 1:54 p.m.

esteban, there is a really good groundcover calculator at this website: www.briggstree.com, which for some reason is not up at the moment. On the home page, look for the reference section. There are other calculators on-line, I just rely on Briggs' because I know them and I know it works.

Soil prep is pretty minimal. Install your irrigation first (drip is great), level the soil, I add a little bit of worm castings and some Perfect Blend fertilizer to each planting hole, but that's it. Mulch between plants after you plant. Its not a small job but it isn't difficult

Nan Sterman | at 1:54 p.m.

How many plugs of Carex pansa or Carex praegracilis would I need to get for an 1900 sq foot area? What soil prep would need to done before planting?

esteban | at 1:50 p.m.

Pizzaguy - Follow-up to sprinkler question and plum fruits splitting:

Current tree irrigation is spray and shared with adjacent grass. Irrigation is scheduled every-other day for about 9 minutes (two 3-minute interval before sunrise and one 3 minute interval at 10PM).

We are 3 miles form the ocean and experience a lot of evening moisture outside the summer (we dial down the irrigation during cooler months).

The solution to your plum issue is to change the irrigation! Trees and grass do not belong on the same irrigation zone. Your fruit trees need deep irrigation (as noted before) while grass is fine with a minimal sprinkle. Think about the goal - to wet the soil as deep as the roots are. Grass roots go a few inches down, tree roots go for several feet. I suggest you rethink and redo the irrigation. Put the plum tree (and any other stone fruit trees) on a drip or bubble zone that goes for a long time, once a week at max in summer.

I would also cut down on the grass irrigation - its way too much. And eliminate the night time watering, that encourages fungus (which is what you are seeing on the fruits).

As you work to determining a new schedule, use the "moisture sensor" at the tip of your arm. Dig down and see when exactly the soil is dry. That's when it is time to water, not before. You might also benefit from a weather based irrigation controller which "decides" when and how much to water based on your location, the weather, and the type of soil/plants in each irrigation zone. If you go that route, be sure to have someone who knows what they are doing program it.

Nan Sterman | at 1:49 p.m.

Pizzaguy - As for your clay/sandy loam soil, the trend of amending soil has thankfully passed. We now plant into unamended soil as much as possible - otherwise, research shows that plant roots stay in the planting hole with the "good" soil, rather than reach out into the "bad" soil. Truth is, the plants will adapt.

My only question for you about the clay is whether it is hardpan and stops water from draining down past it. If so, then you need to do much more than amend the soil.

Nan Sterman | at 1:44 p.m.

Pizzaguy - As for your clay/sandy loam soil, the trend of amending soil has thankfully passed. We now plant into unamended soil as much as possible - otherwise, research shows that plant roots stay in the planting hole with the "good" soil, rather than reach out into the "bad" soil. Truth is, the plants will adapt.

My only question for you about the clay is whether it is hardpan and stops water from draining down past it. If so, then you need to do much more than amend the soil.

Nan Sterman | at 1:44 p.m.

Follow-up to sprinkler question:

Current tree irrigation is spray and shared with adjacent grass. Irrigation is scheduled every-other day for about 9 minutes (two 3-minute interval before sunrise and one 3 minute interval at 10PM).

We are 3 miles form the ocean and experience a lot of evening moisture outside the summer (we dial down the irrigation during cooler months).

Pizzaguy | at 1:43 p.m.

Response to follow-up on drainage:

- Sprinklers water away from the house.

- I appreciate your suggestion on drainage, and will try that next.
Since I am going to contract a bobcat to grade, I wanted to see if I need to amend the clay, which lies beneath 5 inches of topsoil. Thanks!

Pizzaguy | at 1:41 p.m.

Fred, If the problem is when you irrigate, then the solution would be to irrigate for shorter periods of time, even if that meant that you had to irrigate more often. That would give the water time to percolate down into the soil. What kind of shrubs are they and how often/ how long do you water now?

As for holding water when it rains, that's a tough one - there is root barrier, essentially sheets of thin plastic that would fit the space but they are not water tight and I'm not sure how much water they would hold as the water rises behind the barrier and puts pressure on it.

Can you look for a different solution, like weep holes in the wall, that would let the water drain out at a measured but constant rate?

Nan Sterman | at 1:41 p.m.

Both. I have mature shrubs in the area and due to the decomposed granite in which they reside I also have a problem with their being root bound. They are healthy and have been there for many years. I just want to retain the water. I do use drip irrigation but I would like to have an edging material that is about 12" high so that the water stays where it should be. Do you know of a flexible material that I could use for that purpose?

fdavis | at 1:37 p.m.

Generally, Carex pansa is purchased by the plug (so is Carex praegracilis). There are several wholesale nurseries in San Diego that grow them. Ask at your local nursery to see if they can order them for you. If not, email me at info@plantsoup.com and I can make arrangements.

Nan Sterman | at 1:36 p.m.

where can you find the Carex pansa?

stareijuarez | at 1:35 p.m.

Pizzaguy as for your plum trees! That sounds like an overwatering or erratic watering issue as well. Fruits don't usually split like that - but once they do, they are an open wound so of course fungus would set in. Fruit trees, like all other plants, prefer deep water but don't need it all that often except in the fruiting season. I would wait until next year, and in the meantime, redo your irrigation system if needed, but definitely rethink your irrigation schedule. Do you know how often you are watering now? And what technology - bubblers, spray, drip, hand watering?

Nan Sterman | at 1:34 p.m.

Pizza guy, do your sprinklers shoot towards the house? If so, they need to be moved so they shoot away from the house. Grade makes a huge difference, so please don't discount that as a contributor, if not the main issue.

If you are watering every other day, that concerns me as well. Does teh soil dry out enough that it requires water that often? Most lawns, even this time of year, can get by on two or three times a week.

Think of it this way - soil is like a sponge. It has air spaces that fill up when we water. Any water you add once the air spaces are filled, has no place to go, so it runs off. I suspect that if you cut back on water frequency, you could solve your problem.

Nan Sterman | at 1:30 p.m.

Follow-up to earlier question:

Q. If you have clay/sandy loam soil, then the drainage should already be pretty good. What are you seeing that makes you think that the drainage is a problem?

Reply:
The soil around the house foundation remains moist after adjusting for minimal lawn irrigation times using every-other-day schedules. There are no pipe leaks inside or outside the house. Slope could use some improvement, but the topsoil drains during the off-water day.

Q. As for the plum trees, can you describe the problem a bit so I get a clearer picture of the fungus situation?

The fruit on the trees would develop a tear before ripening and fungus would grow from the tear/scar. The fruit would eventually become covered by spores and ferment.

Pizzaguy | at 1:26 p.m.

Fred, can you give me a little more information? Is this an issue of retaining water when you irrigate or when it rains?

Nan Sterman | at 1:26 p.m.

It is a small area about 18" wide that is between the street curb and a retaining wall. I cannot change the grade. Are you aware of a product that would keep the water within a space that is about 12" high? Thanks again, Fred

fdavis | at 1:24 p.m.

If that is the case, Itowne, you can grow any orange tree in your garden. Think about the types of oranges you prefer - eating or juicing, and if there is a particular time of year that you like to eat oranges. For example, in summer, when the stone fruits are all ripening, my family chooses them over citrus, so I choose citrus that ripen from fall through late spring. If you go to this website: http://www.lavernenursery.com/products/citurs.html, you can see most of the oranges commonly available in the nurseries. Each is described in terms of its characteristics (size, hardiness, etc.) including the season you can expect them to ripen in.

Nan Sterman | at 1:24 p.m.

We have some freezing nights. But mostly in the low 40's

ltowne | at 1:19 p.m.

Fred, are you having trouble with runoff? If so, then the best solution would be to change the grade so that the water stays on site rather than flowing off site. Am I understanding you correctly?

Nan Sterman | at 1:18 p.m.

Hi I was wondering if you knew of an edging product that I could use to keep water on my property. I think that it should be around 12" high so that I could bury it in the soil. I have plants immediately abutting the curb, Thanks, Fred

fdavis | at 1:16 p.m.

Itowne, how cold does your garden get in winter?

Nan Sterman | at 1:14 p.m.

What variety of orange tree would you recommend for east county?

ltowne | at 1:14 p.m.

If you have clay/sandy loam soil, then the drainage should already be pretty good. What are you seeing that makes you think that the drainage is a problem?

As for the plum trees, can you describe the problem a bit so I get a clearer picture of the fungus situation?

Nan Sterman | at 1:12 p.m.

I have clay/sandy loam soil and would like to amend it to promote drainage of my garden.

I also removed some plum trees due to fungus - should I get rid of the topsoil around the trees?

Any suggestions? Thanks in advance

Pizzaguy | at 1:11 p.m.

The natives I mentioned were Carex pansa and Carex praegracilis. They look like grass and grow like grass but are actually in a group of plants commonly called "sedges." If you look for them in the nursery, they will look virtually identical to you.

Nan Sterman | at 1:11 p.m.

What were the names of those California native grasses?

esteban | at 1:09 p.m.

Welcome to our live chat - I'm here to answer your gardening questions between now and 2 pm (PST) so fire away!

Nan Sterman | at 1:03 p.m.