Stephen Brueggerhoff, CEA – Horticulture; Texas A&M AgriLife Extension Service
9/30/2023
Last December’s hard freeze set back homeowners reestablishing citrus trees. A few residents that I have talked with swear they will never grow citrus again. My advice is to not give in to the vagaries of old man winter, to continue planting in-ground and consider growing citrus in containers. There are a number of advantages with container grown citrus: flexibility relocating plants before freeze events; great for homes with limited outdoor space; and cold sensitive varietals cultivated outside of their natural range.
For growing conditions, provide basic requirements with 6 to 8 hours full sun exposure, apply consistent water and scheduled fertilizer application. Consider container type and size in relation to varietal growth habit. The type of container is dependent on your practical situation; molded plastic is lighter for ease of movement, terracotta and ceramic are heavier and larger containers may crack when moved. Eventually the purchased container size must be potted up to 20-gallons minimum, a size appropriate to establish a healthy root system that will support top growth and fruit production. Upsizing should be performed incrementally at 25% more pot size; too much soil volume to root ratio disrupts equal distribution of water throughout the container. An example would be repotting from a ten-gallon to a twelve-gallon container. Assess the root zone annually to determine if repotting is necessary and expect repotting every 3 years. Replant with similar techniques used for planting in ground: wash off the old media, prune malformed roots, plant at the same depth, etc.
Consider growth habit as each type of citrus has its own form, growth rate and eventual size. The largest trees such as Navel oranges, grapefruit and pomelo can reach 15-feet or more in-ground and may not be practical for containers; lemons could work and come in close to 15-feet; mandarin, satsuma oranges and lime trees to 12-feet. Citrus can be kept smaller stature depending on specific types of grafted rootstock. Unless otherwise stated, commercial citrus varieties are grafted onto a stump (rootstock) of a compatible sour orange. Trifoliate orange (Poncirus trifoliata) is generally used, is a cold tolerant sour orange species and has the potential to dwarf top growth to 10-feet. Varietal ‘Flying Dragon’ (P. trifoliata var. monstrosa) offers the same climatic tolerance and is known to keep species 6 to 8-feet. Research the grafted rootstock of your desired citrus tree prior to purchase.
Nutrient availability is managed through scheduled fertilizer applications. The primary nutrients listed on a fertilizer product are based on a percentage of nitrogen, phosphorous and potassium, represented numerically and in the order listed. Fertilizer ratio and application rates are calculated primarily for in-ground trees and related to trunk size and identified nutrient deficiencies. For containers, it is best to use products with a 2-1-1 or 3-1-2 ratio. Fertilizer can be slow release prils or water-soluble granules, and commercial products will have recommended application information on the label. I have had success with a product marketed for citrus, rated 10-2-8 as a water-soluble fertilizer, applied three times at 1 cup (.5-lbs) each application. Timing for the application is mid-February, early May, and final mid-June. Fertilizer products are formulated from salts as mineralized elements. These salts will accumulate over time in the media; visible signs will be a thin sheen or crystallized crust on soil surface, as well as brown leaf tips, reduced growth, and unusual wilting. You will have to water flush accumulated salts from the soil every few years. Keep in mind that you will have to increase fertilizer amounts as the tree matures. Supplement with liquid fertilizers as needed and regarding identified nutrient deficiencies.
Life is a bit brighter with citrus, we continue to celebrate citriculture through education programs like our Gulf Coast Gardening Seminar Patio Citrus on October 7. Keep up to date on our offerings through Galveston County AgriLife Extension (https://galveston.agrilife.org) and Galveston County Master Gardener (GCMGA) website: https://txmg.org/galveston. Mark your calendar for our GCMGA annual Fall Festival October 21. Keep on the sunny side and I’ll see you in the garden.
